wdiff draft-ietf-detnet-use-cases-11.txt draft-ietf-detnet-use-cases-12.txt

Internet Engineering Task Force E. Grossman, Ed.
Internet-Draft DOLBY
Intended status: Informational C. Gunther
Expires: April 6, October 5, 2017 HARMAN
P. Thubert
P. Wetterwald
CISCO
J. Raymond
HYDRO-QUEBEC
J. Korhonen
BROADCOM
Y. Kaneko
Toshiba
S. Das
Applied Communication Sciences
Y. Zha
HUAWEI
B. Varga
J. Farkas
Ericsson
F. Goetz
J. Schmitt
Siemens
X. Vilajosana
Worldsensing
T. Mahmoodi
King's College London
S. Spirou
Intracom Telecom
P. Vizarreta
Technical University of Munich, TUM
October
April 3, 2016 2017

Deterministic Networking Use Cases
draft-ietf-detnet-use-cases-11
draft-ietf-detnet-use-cases-12

Abstract

This draft documents requirements in several diverse industries to
establish multi-hop paths for characterized flows with deterministic
properties. In this context deterministic implies that streams can
be established which provide guaranteed bandwidth and latency which
can be established from either a Layer 2 or Layer 3 (IP) interface,
and which can co-exist on an IP network with best-effort traffic.

Additional requirements include optional redundant paths, very high
reliability paths, time synchronization, and clock distribution.

Industries considered include wireless for industrial applications,
professional audio, electrical utilities, building automation
systems, radio/mobile access networks, automotive, and gaming.

For each case, this document will identify the application, identify
representative solutions used today, and what new uses an IETF DetNet
solution may enable.

Status of This Memo

This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.

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time. It is inappropriate to use Internet-Drafts as reference
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This Internet-Draft will expire on April 6, October 5, 2017.

This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of
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Table of Contents

1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 5
2. Pro Audio and Video . . . . . . . . . . . . . . . . . . . . . 6
2.1. Use Case Description . . . . . . . . . . . . . . . . . . 6
2.1.1. Uninterrupted Stream Playback . . . . . . . . . . . . 6 7
2.1.2. Synchronized Stream Playback . . . . . . . . . . . . 7
2.1.3. Sound Reinforcement . . . . . . . . . . . . . . . . . 7 8
2.1.4. Deterministic Time to Establish Streaming . . . . . . 8
2.1.5. Secure Transmission . . . . . . . . . . . . . . . . . 8
2.1.5.1. Safety . . . . . . . . . . . . . . . . . . . . . 8
2.2. Pro Audio Today . . . . . . . . . . . . . . . . . . . . . 9
2.3. Pro Audio Future . . . . . . . . . . . . . . . . . . . . 9
2.3.1. Layer 3 Interconnecting Layer 2 Islands . . . . . . . 9
2.3.2. High Reliability Stream Paths . . . . . . . . . . . . 9
2.3.3. Integration of Reserved Streams into IT Networks . . 9
2.3.4. Use of Unused Reservations by Best-Effort Traffic . . 10
2.3.5. Traffic Segregation . . . . . . . . . . . . . . . . . 10
2.3.5.1. Packet Forwarding Rules, VLANs and Subnets . . . 10
2.3.5.2. Multicast Addressing (IPv4 and IPv6) . . . . . . 11
2.3.6. Latency Optimization by a Central Controller . . . . 11
2.3.7. Reduced Device Cost Due To Reduced Buffer Memory . . 11
2.4. Pro Audio Asks . . . . . . . . . . . . . . . . . . . . . 12
3. Electrical Utilities . . . . . . . . . . . . . . . . . . . . 12
3.1. Use Case Description . . . . . . . . . . . . . . . . . . 12
3.1.1. Transmission Use Cases . . . . . . . . . . . . . . . 12
3.1.1.1. Protection . . . . . . . . . . . . . . . . . . . 12
3.1.1.2. Intra-Substation Process Bus Communications . . . 18
3.1.1.3. Wide Area Monitoring and Control Systems . . . . 19
3.1.1.4. IEC 61850 WAN engineering guidelines requirement
classification . . . . . . . . . . . . . . . . . 20
3.1.2. Generation Use Case . . . . . . . . . . . . . . . . . 21
3.1.2.1. Control of the Generated Power . . . . . . . . . 21
3.1.2.2. Control of the Generation Infrastructure . . . . 22
3.1.3. Distribution use case . . . . . . . . . . . . . . . . 27
3.1.3.1. Fault Location Isolation and Service Restoration
(FLISR) . . . . . . . . . . . . . . . . . . . . . 27
3.2. Electrical Utilities Today . . . . . . . . . . . . . . . 28
3.2.1. Security Current Practices and Limitations . . . . . 28
3.3. Electrical Utilities Future . . . . . . . . . . . . . . . 30
3.3.1. Migration to Packet-Switched Network . . . . . . . . 31
3.3.2. Telecommunications Trends . . . . . . . . . . . . . . 31
3.3.2.1. General Telecommunications Requirements . . . . . 31
3.3.2.2. Specific Network topologies of Smart Grid
Applications . . . . . . . . . . . . . . . . . . 32
3.3.2.3. Precision Time Protocol . . . . . . . . . . . . . 33
3.3.3. Security Trends in Utility Networks . . . . . . . . . 34
3.4. Electrical Utilities Asks . . . . . . . . . . . . . . . . 36
4. Building Automation Systems . . . . . . . . . . . . . . . . . 36
4.1. Use Case Description . . . . . . . . . . . . . . . . . . 36
4.2. Building Automation Systems Today . . . . . . . . . . . . 37
4.2.1. BAS Architecture . . . . . . . . . . . . . . . . . . 37
4.2.2. BAS Deployment Model . . . . . . . . . . . . . . . . 38
4.2.3. Use Cases for Field Networks . . . . . . . . . . . . 40
4.2.3.1. Environmental Monitoring . . . . . . . . . . . . 40
4.2.3.2. Fire Detection . . . . . . . . . . . . . . . . . 40
4.2.3.3. Feedback Control . . . . . . . . . . . . . . . . 41
4.2.4. Security Considerations . . . . . . . . . . . . . . . 41
4.3. BAS Future . . . . . . . . . . . . . . . . . . . . . . . 41
4.4. BAS Asks . . . . . . . . . . . . . . . . . . . . . . . . 42
5. Wireless for Industrial . . . . . . . . . . . . . . . . . . . 42
5.1. Use Case Description . . . . . . . . . . . . . . . . . . 42
5.1.1. Network Convergence using 6TiSCH . . . . . . . . . . 43
5.1.2. Common Protocol Development for 6TiSCH . . . . . . . 43
5.2. Wireless Industrial Today . . . . . . . . . . . . . . . . 44
5.3. Wireless Industrial Future . . . . . . . . . . . . . . . 44
5.3.1. Unified Wireless Network and Management . . . . . . . 44
5.3.1.1. PCE and 6TiSCH ARQ Retries . . . . . . . . . . . 46
5.3.2. Schedule Management by a PCE . . . . . . . . . . . . 47
5.3.2.1. PCE Commands and 6TiSCH CoAP Requests . . . . . . 47
5.3.2.2. 6TiSCH IP Interface . . . . . . . . . . . . . . . 48
5.3.3. 6TiSCH Security Considerations . . . . . . . . . . . 49
5.4. Wireless Industrial Asks . . . . . . . . . . . . . . . . 49
6. Cellular Radio . . . . . . . . . . . . . . . . . . . . . . . 49
6.1. Use Case Description . . . . . . . . . . . . . . . . . . 49
6.1.1. Network Architecture . . . . . . . . . . . . . . . . 49
6.1.2. Delay Constraints . . . . . . . . . . . . . . . . . . 50
6.1.3. Time Synchronization Constraints . . . . . . . . . . 51
6.1.4. Transport Loss Constraints . . . . . . . . . . . . . 53
6.1.5. Security Considerations . . . . . . . . . . . . . . . 53
6.2. Cellular Radio Networks Today . . . . . . . . . . . . . . 54
6.2.1. Fronthaul . . . . . . . . . . . . . . . . . . . . . . 54
6.2.2. Midhaul and Backhaul . . . . . . . . . . . . . . . . 54
6.3. Cellular Radio Networks Future . . . . . . . . . . . . . 55
6.4. Cellular Radio Networks Asks . . . . . . . . . . . . . . 57
7. Industrial M2M . . . . . . . . . . . . . . . . . . . . . . . 57
7.1. Use Case Description . . . . . . . . . . . . . . . . . . 57
7.2. Industrial M2M Communication Today . . . . . . . . . . . 58
7.2.1. Transport Parameters . . . . . . . . . . . . . . . . 59
7.2.2. Stream Creation and Destruction . . . . . . . . . . . 60
7.3. Industrial M2M Future . . . . . . . . . . . . . . . . . . 60
7.4. Industrial M2M Asks . . . . . . . . . . . . . . . . . . . 60
8. Use Case Common Elements Themes . . . . . . . . . . . . . . . . . . . 60
9. Use Cases Explicitly Out of Scope for DetNet
8.1. Unified, standards-based network . . . . . . . . . . . . 61
9.1. DetNet Scope Limitations
8.1.1. Extensions to Ethernet . . . . . . . . . . . . . . . 61
8.1.2. Centrally Administered . 62
9.2. Internet-based Applications . . . . . . . . . . . . . . 61
8.1.3. Standardized Data Flow Information Models . . 62
9.2.1. Use Case Description . . . . 61
8.1.4. L2 and L3 Integration . . . . . . . . . . . . . . . 62
9.2.1.1. Media Content . 61
8.1.5. Guaranteed End-to-End Delivery . . . . . . . . . . . 61
8.1.6. Replacement for Multiple Proprietary Deterministic
Networks . . 63
9.2.1.2. Online Gaming . . . . . . . . . . . . . . . . . . 63
9.2.1.3. Virtual Reality . . 61
8.1.7. Mix of Deterministic and Best-Effort Traffic . . . . 62
8.1.8. Unused Reserved BW to be Available to Best Effort
Traffic . . . . . . . . . . . 63
9.2.2. Internet-Based Applications Today . . . . . . . . . . 63
9.2.3. Internet-Based Applications Future . . 62

8.1.9. Lower Cost, Multi-Vendor Solutions . . . . . . . 63
9.2.4. Internet-Based Applications Asks . . 62
8.2. Scalable Size . . . . . . . . 63
9.3. Pro Audio and Video - Digital Rights Management (DRM) . . 64
9.4. Pro Audio and Video - Link Aggregation . . . . . . . . . 64
10. Acknowledgments . . . 62
8.3. Scalable Timing Parameters and Accuracy . . . . . . . . . 62
8.3.1. Bounded Latency . . . . . . . . . . . 65
10.1. Pro Audio . . . . . . . . 62
8.3.2. Low Latency . . . . . . . . . . . . . . . 65
10.2. Utility Telecom . . . . . . 63
8.3.3. Symmetrical Path Delays . . . . . . . . . . . . . . 65
10.3. Building Automation Systems . 63
8.4. High Reliability and Availability . . . . . . . . . . . . 63
8.5. Security . 65
10.4. Wireless for Industrial . . . . . . . . . . . . . . . . 65
10.5. Cellular Radio . . . . . . . 63
8.6. Deterministic Flows . . . . . . . . . . . . . . 66
10.6. Industrial M2M . . . . . 64
9. Use Cases Explicitly Out of Scope for DetNet . . . . . . . . 64
9.1. DetNet Scope Limitations . . . . . . . . . . . . . 66
10.7. Internet . . . 64
9.2. Internet-based Applications and CoMP . . . . . . . . . . . . . 66
10.8. Electrical Utilities . . 65
9.2.1. Use Case Description . . . . . . . . . . . . . . . . 66
11. Informative References 65
9.2.1.1. Media Content Delivery . . . . . . . . . . . . . 65
9.2.1.2. Online Gaming . . . . . . 66
Authors' Addresses . . . . . . . . . . . . 65
9.2.1.3. Virtual Reality . . . . . . . . . . . 76

1. Introduction

This draft presents use cases from diverse industries which . . . . . . 65
9.2.2. Internet-Based Applications Today . . . . . . . . . . 65
9.2.3. Internet-Based Applications Future . . . . . . . . . 65
9.2.4. Internet-Based Applications Asks . . . . . . . . . . 66
9.3. Pro Audio and Video - Digital Rights Management (DRM) . . 66
9.4. Pro Audio and Video - Link Aggregation . . . . . . . . . 66
10. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 67
10.1. Pro Audio . . . . . . . . . . . . . . . . . . . . . . . 67
10.2. Utility Telecom . . . . . . . . . . . . . . . . . . . . 67
10.3. Building Automation Systems . . . . . . . . . . . . . . 67
10.4. Wireless for Industrial . . . . . . . . . . . . . . . . 67
10.5. Cellular Radio . . . . . . . . . . . . . . . . . . . . . 68
10.6. Industrial M2M . . . . . . . . . . . . . . . . . . . . . 68
10.7. Internet Applications and CoMP . . . . . . . . . . . . . 68
10.8. Electrical Utilities . . . . . . . . . . . . . . . . . . 68
11. Informative References . . . . . . . . . . . . . . . . . . . 68
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 78

1. Introduction

This draft presents use cases from diverse industries which have in
common a need for deterministic streams, but which also differ
notably in their network topologies and specific desired behavior.
Together, they provide broad industry context for DetNet and a
yardstick against which proposed DetNet designs can be measured (to
what extent does a proposed design satisfy these various use cases?)

For DetNet, use cases explicitly do not define requirements; The
DetNet WG will consider the use cases, decide which elements are in
scope for DetNet, and the results will be incorporated into future
drafts. Similarly, the DetNet use case draft explicitly does not
suggest any specific design, architecture or protocols, which will be
topics of future drafts.

We present for each use case the answers to the following questions:

o What is the use case?

o How is it addressed today?

o How would you like it to be addressed in the future?

o What do you want the IETF to deliver?

The level of detail in each use case should be sufficient to express
the relevant elements of the use case, but not more.

At the end we consider the use cases collectively, and examine the
most significant goals they have in common.

2. Pro Audio and Video

2.1. Use Case Description

The professional audio and video industry ("ProAV") includes:

o Music and film content creation

o Broadcast

o Cinema

o Live sound

o Public address, media and emergency systems at large venues
(airports, stadiums, churches, theme parks).

These industries have already transitioned audio and video signals
from analog to digital. However, the digital interconnect systems
remain primarily point-to-point with a single (or small number of)
signals per link, interconnected with purpose-built hardware.

These industries are now transitioning to packet-based infrastructure
to reduce cost, increase routing flexibility, and integrate with
existing IT infrastructure.

Today ProAV applications have no way to establish deterministic
streams from a standards-based Layer 3 (IP) interface, which is a
fundamental limitation to the use cases described here. Today
deterministic streams can be created within standards-based layer 2
LANs (e.g. using IEEE 802.1 AVB) however these are not routable via
IP and thus are not effective for distribution over wider areas (for
example broadcast events that span wide geographical areas).

It would be highly desirable if such streams could be routed over the
open Internet, however solutions with more limited scope (e.g.
enterprise networks) would still provide a substantial improvement.

The following sections describe specific ProAV use cases.

2.1.1. Uninterrupted Stream Playback

Transmitting audio and video streams for live playback is unlike
common file transfer because uninterrupted stream playback in the
presence of network errors cannot be achieved by re-trying the
transmission; by the time the missing or corrupt packet has been
identified it is too late to execute a re-try operation. Buffering
can be used to provide enough delay to allow time for one or more
retries, however this is not an effective solution in applications
where large delays (latencies) are not acceptable (as discussed
below).

Streams with guaranteed bandwidth can eliminate congestion on the
network as a cause of transmission errors that would lead to playback
interruption. Use of redundant paths can further mitigate
transmission errors to provide greater stream reliability.

2.1.2. Synchronized Stream Playback

Latency in this context is the time between when a signal is
initially sent over a stream and when it is received. A common
example in ProAV is time-synchronizing audio and video when they take
separate paths through the playback system. In this case the latency
of both the audio and video streams must be bounded and consistent if
the sound is to remain matched to the movement in the video. A
common tolerance for audio/video sync is one NTSC video frame (about
33ms) and to maintain the audience perception of correct lip sync the
latency needs to be consistent within some reasonable tolerance, for
example 10%.

A common architecture for synchronizing multiple streams that have
different paths through the network (and thus potentially different
latencies) is to enable measurement of the latency of each path, and
have the data sinks (for example speakers) delay (buffer) all packets
on all but the slowest path. Each packet of each stream is assigned
a presentation time which is based on the longest required delay.
This implies that all sinks must maintain a common time reference of
sufficient accuracy, which can be achieved by any of various
techniques.

This type of architecture is commonly implemented using a central
controller that determines path delays and arbitrates buffering
delays.

2.1.3. Sound Reinforcement

Consider the latency (delay) from when a person speaks into a
microphone to when their voice emerges from the speaker. If this
delay is longer than about 10-15 milliseconds it is noticeable and
can make a sound reinforcement system unusable (see slide 6 of
[SRP_LATENCY]). (If you have ever tried to speak in the presence of
a delayed echo of your voice you may know this experience).

Note that the 15ms latency bound includes all parts of the signal
path, not just the network, so the network latency must be
significantly less than 15ms.

In some cases local performers must perform in synchrony with a
remote broadcast. In such cases the latencies of the broadcast
stream and the local performer must be adjusted to match each other,
with a worst case of one video frame (33ms for NTSC video).

In cases where audio phase is a consideration, for example beam-
forming using multiple speakers, latency requirements can be in the
10 microsecond range (1 audio sample at 96kHz).

2.1.4. Deterministic Time to Establish Streaming

Note: It is still under The WG discussion whether this topic (stream
startup time) is within scope of DetNet.

Some audio systems installed in public environments (airports,
hospitals) have unique requirements with regards to health, safety
and fire concerns. One such requirement is a maximum of 3 seconds has decided that guidelines for a system to respond to an emergency detection and begin sending
appropriate warning signals and alarms without human intervention.
For this requirement to be met, the system must support a bounded and
acceptable deterministic time from a notification signal to specific
establish stream
establishment. For further details see [ISO7240-16].

Similar requirements apply when the system startup is restarted after a power
cycle, cable re-connection, or system reconfiguration.

In many cases such re-establishment not within scope of streaming state must be
achieved by the peer devices themselves, i.e. without a central
controller (since such a controller may only be present during
initial network configuration).

Video systems introduce related requirements, for example when
transitioning from one camera feed (video stream) DetNet. If bounded
timing of establishing or re-establish streams is required in a given
use case, it is up to another (see
[STUDIO_IP] and [ESPN_DC2]). the application/system to achieve this. (The
supporting text from this section has been removed as of draft 12).

2.1.5. Secure Transmission

2.1.5.1. Safety

Professional audio systems can include amplifiers that are capable of
generating hundreds or thousands of watts of audio power which if
used incorrectly can cause hearing damage to those in the vicinity.
Apart from the usual care required by the systems operators to
prevent such incidents, the network traffic that controls these
devices must be secured (as with any sensitive application traffic).

2.2. Pro Audio Today

Some proprietary systems have been created which enable deterministic
streams at Layer 3 however they are "engineered networks" which
require careful configuration to operate, often require that the
system be over-provisioned, and it is implied that all devices on the
network voluntarily play by the rules of that network. To enable
these industries to successfully transition to an interoperable
multi-vendor packet-based infrastructure requires effective open
standards, and we believe that establishing relevant IETF standards
is a crucial factor.

2.3. Pro Audio Future

2.3.1. Layer 3 Interconnecting Layer 2 Islands

It would be valuable to enable IP to connect multiple Layer 2 LANs.

As an example, ESPN recently constructed a state-of-the-art 194,000
sq ft, $125 million broadcast studio called DC2. The DC2 network is
capable of handling 46 Tbps of throughput with 60,000 simultaneous
signals. Inside the facility are 1,100 miles of fiber feeding four
audio control rooms (see [ESPN_DC2] ).

In designing DC2 they replaced as much point-to-point technology as
they could with packet-based technology. They constructed seven
individual studios using layer 2 LANS (using IEEE 802.1 AVB) that
were entirely effective at routing audio within the LANs. However to
interconnect these layer 2 LAN islands together they ended up using
dedicated paths in a custom SDN (Software Defined Networking) router
because there is no standards-based routing solution available.

2.3.2. High Reliability Stream Paths

On-air and other live media streams are often backed up with
redundant links that seamlessly act to deliver the content when the
primary link fails for any reason. In point-to-point systems this is
provided by an additional point-to-point link; the analogous
requirement in a packet-based system is to provide an alternate path
through the network such that no individual link can bring down the
system.

2.3.3. Integration of Reserved Streams into IT Networks

A commonly cited goal of moving to a packet based media
infrastructure is that costs can be reduced by using off the shelf,
commodity network hardware. In addition, economy of scale can be
realized by combining media infrastructure with IT infrastructure.

In keeping with these goals, stream reservation technology should be
compatible with existing protocols, and not compromise use of the
network for best effort (non-time-sensitive) traffic.

2.3.4. Use of Unused Reservations by Best-Effort Traffic

In cases where stream bandwidth is reserved but not currently used
(or is under-utilized) that bandwidth must be available to best-
effort (i.e. non-time-sensitive) traffic. For example a single
stream may be nailed up (reserved) for specific media content that
needs to be presented at different times of the day, ensuring timely
delivery of that content, yet in between those times the full
bandwidth of the network can be utilized for best-effort tasks such
as file transfers.

This also addresses a concern of IT network administrators that are
considering adding reserved bandwidth traffic to their networks that
("users will reserve large quantities of bandwidth and then never un-
reserve it even though they are not using it, and soon the network
will have no bandwidth left").

2.3.5. Traffic Segregation

Note: It is still under WG discussion whether this topic will be
addressed by DetNet.

Sink devices may be low cost devices with limited processing power.
In order to not overwhelm the CPUs in these devices it is important
to limit the amount of traffic that these devices must process.

As an example, consider the use of individual seat speakers in a
cinema. These speakers are typically required to be cost reduced
since the quantities in a single theater can reach hundreds of seats.
Discovery protocols alone in a one thousand seat theater can generate
enough broadcast traffic to overwhelm a low powered CPU. Thus an
installation like this will benefit greatly from some type of traffic
segregation that can define groups of seats to reduce traffic within
each group. All seats in the theater must still be able to
communicate with a central controller.

There are many techniques that can be used to support this
requirement including (but not limited to) the following examples.

2.3.5.1. Packet Forwarding Rules, VLANs and Subnets

Packet forwarding rules can be used to eliminate some extraneous
streaming traffic from reaching potentially low powered sink devices,
however there may be other types of broadcast traffic that should be
eliminated using other means for example VLANs or IP subnets.

2.3.5.2. Multicast Addressing (IPv4 and IPv6)

Multicast addressing is commonly used to keep bandwidth utilization
of shared links to a minimum.

Because of the MAC Address forwarding nature of Layer 2 bridges it is
important that a multicast MAC address is only associated with one
stream. This will prevent reservations from forwarding packets from
one stream down a path that has no interested sinks simply because
there is another stream on that same path that shares the same
multicast MAC address.

Since each multicast MAC Address can represent 32 different IPv4
multicast addresses there must be a process put in place to make sure
this does not occur. Requiring use of IPv6 address can achieve this,
however due to their continued prevalence, solutions that are
effective for IPv4 installations are also required.

2.3.6. Latency Optimization by a Central Controller

A central network controller might also perform optimizations based
on the individual path delays, for example sinks that are closer to
the source can inform the controller that they can accept greater
latency since they will be buffering packets to match presentation
times of farther away sinks. The controller might then move a stream
reservation on a short path to a longer path in order to free up
bandwidth for other critical streams on that short path. See slides
3-5 of [SRP_LATENCY].

Additional optimization can be achieved in cases where sinks have
differing latency requirements, for example in a live outdoor concert
the speaker sinks have stricter latency requirements than the
recording hardware sinks. See slide 7 of [SRP_LATENCY].

2.3.7. Reduced Device Cost Due To Reduced Buffer Memory

Device cost can be reduced in a system with guaranteed reservations
with a small bounded latency due to the reduced requirements for
buffering (i.e. memory) on sink devices. For example, a theme park
might broadcast a live event across the globe via a layer 3 protocol;
in such cases the size of the buffers required is proportional to the
latency bounds and jitter caused by delivery, which depends on the
worst case segment of the end-to-end network path. For example on
todays open internet the latency is typically unacceptable for audio
and video streaming without many seconds of buffering. In such
scenarios a single gateway device at the local network that receives
the feed from the remote site would provide the expensive buffering
required to mask the latency and jitter issues associated with long
distance delivery. Sink devices in the local location would have no
additional buffering requirements, and thus no additional costs,
beyond those required for delivery of local content. The sink device
would be receiving the identical packets as those sent by the source
and would be unaware that there were any latency or jitter issues
along the path.

2.4. Pro Audio Asks

o Layer 3 routing on top of AVB (and/or other high QoS networks)

o Content delivery with bounded, lowest possible latency

o IntServ and DiffServ integration with AVB (where practical)

o Single network for A/V and IT traffic

o Standards-based, interoperable, multi-vendor

o IT department friendly

o Enterprise-wide networks (e.g. size of San Francisco but not the
whole Internet (yet...))

3. Electrical Utilities

3.1. Use Case Description

Many systems that an electrical utility deploys today rely on high
availability and deterministic behavior of the underlying networks.
Here we present use cases in Transmission, Generation and
Distribution, including key timing and reliability metrics. We also
discuss security issues and industry trends which affect the
architecture of next generation utility networks

3.1.1. Transmission Use Cases

3.1.1.1. Protection

Protection means not only the protection of human operators but also
the protection of the electrical equipment and the preservation of
the stability and frequency of the grid. If a fault occurs in the
transmission or distribution of electricity then severe damage can
occur to human operators, electrical equipment and the grid itself,
leading to blackouts.

Communication links in conjunction with protection relays are used to
selectively isolate faults on high voltage lines, transformers,
reactors and other important electrical equipment. The role of the
teleprotection system is to selectively disconnect a faulty part by
transferring command signals within the shortest possible time.

3.1.1.1.1. Key Criteria

The key criteria for measuring teleprotection performance are command
transmission time, dependability and security. These criteria are
defined by the IEC standard 60834 as follows:

o Transmission time (Speed): The time between the moment where state
changes at the transmitter input and the moment of the
corresponding change at the receiver output, including propagation
delay. Overall operating time for a teleprotection system
includes the time for initiating the command at the transmitting
end, the propagation delay over the network (including equipments)
and the selection and decision time at the receiving end,
including any additional delay due to a noisy environment.

o Dependability: The ability to issue and receive valid commands in
the presence of interference and/or noise, by minimizing the
probability of missing command (PMC). Dependability targets are
typically set for a specific bit error rate (BER) level.

o Security: The ability to prevent false tripping due to a noisy
environment, by minimizing the probability of unwanted commands
(PUC). Security targets are also set for a specific bit error
rate (BER) level.

Additional elements of the the teleprotection system that impact its
performance include:

o Network bandwidth

o Failure recovery capacity (aka resiliency)

3.1.1.1.2. Fault Detection and Clearance Timing

Most power line equipment can tolerate short circuits or faults for
up to approximately five power cycles before sustaining irreversible
damage or affecting other segments in the network. This translates
to total fault clearance time of 100ms. As a safety precaution,
however, actual operation time of protection systems is limited to
70- 80 percent of this period, including fault recognition time,
command transmission time and line breaker switching time.

Some system components, such as large electromechanical switches,
require particularly long time to operate and take up the majority of
the total clearance time, leaving only a 10ms window for the
telecommunications part of the protection scheme, independent of the
distance to travel. Given the sensitivity of the issue, new networks
impose requirements that are even more stringent: IEC standard 61850
limits the transfer time for protection messages to 1/4 - 1/2 cycle
or 4 - 8ms (for 60Hz lines) for the most critical messages.

3.1.1.1.3. Symmetric Channel Delay

Note: It is currently under WG discussion whether symmetric path
delays are to be guaranteed by DetNet.

Teleprotection channels which are differential must be synchronous,
which means that any delays on the transmit and receive paths must
match each other. Teleprotection systems ideally support zero
asymmetric delay; typical legacy relays can tolerate delay
discrepancies of up to 750us.

Some tools available for lowering delay variation below this
threshold are:

o For legacy systems using Time Division Multiplexing (TDM), jitter
buffers at the multiplexers on each end of the line can be used to
offset delay variation by queuing sent and received packets. The
length of the queues must balance the need to regulate the rate of
transmission with the need to limit overall delay, as larger
buffers result in increased latency.

o For jitter-prone IP packet networks, traffic management tools can
ensure that the teleprotection signals receive the highest
transmission priority to minimize jitter.

o Standard packet-based synchronization technologies, such as
1588-2008 Precision Time Protocol (PTP) and Synchronous Ethernet
(Sync-E), can help keep networks stable by maintaining a highly
accurate clock source on the various network devices.

3.1.1.1.4. Teleprotection Network Requirements (IEC 61850)

The following table captures the main network metrics as based on the
IEC 61850 standard.

Table 1: Teleprotection network requirements

3.1.1.1.5. Inter-Trip Protection scheme

"Inter-tripping" is the signal-controlled tripping of a circuit
breaker to complete the isolation of a circuit or piece of apparatus
in concert with the tripping of other circuit breakers.

Table 2: Inter-Trip protection network requirements

3.1.1.1.6. Current Differential Protection Scheme

Current differential protection is commonly used for line protection,
and is typical for protecting parallel circuits. At both end of the
lines the current is measured by the differential relays, and both
relays will trip the circuit breaker if the current going into the
line does not equal the current going out of the line. This type of
protection scheme assumes some form of communications being present
between the relays at both end of the line, to allow both relays to
compare measured current values. Line differential protection
schemes assume a very low telecommunications delay between both
relays, often as low as 5ms. Moreover, as those systems are often
not time-synchronized, they also assume symmetric telecommunications
paths with constant delay, which allows comparing current measurement
values taken at the exact same time.

Table 3: Current Differential Protection metrics

3.1.1.1.7. Distance Protection Scheme

Distance (Impedance Relay) protection scheme is based on voltage and
current measurements. The network metrics are similar (but not
identical to) Current Differential protection.

Table 4: Distance Protection requirements

3.1.1.1.8. Inter-Substation Protection Signaling

This use case describes the exchange of Sampled Value and/or GOOSE
(Generic Object Oriented Substation Events) message between
Intelligent Electronic Devices (IED) in two substations for
protection and tripping coordination. The two IEDs are in a master-
slave mode.

The Current Transformer or Voltage Transformer (CT/VT) in one
substation sends the sampled analog voltage or current value to the
Merging Unit (MU) over hard wire. The MU sends the time-synchronized
61850-9-2 sampled values to the slave IED. The slave IED forwards
the information to the Master IED in the other substation. The
master IED makes the determination (for example based on sampled
value differentials) to send a trip command to the originating IED.
Once the slave IED/Relay receives the GOOSE trip for breaker
tripping, it opens the breaker. It then sends a confirmation message
back to the master. All data exchanges between IEDs are either
through Sampled Value and/or GOOSE messages.

Table 5: Inter-Substation Protection requirements

3.1.1.2. Intra-Substation Process Bus Communications

This use case describes the data flow from the CT/VT to the IEDs in
the substation via the MU. The CT/VT in the substation send the
sampled value (analog voltage or current) to the MU over hard wire.
The MU sends the time-synchronized 61850-9-2 sampled values to the
IEDs in the substation in GOOSE message format. The GPS Master Clock
can send 1PPS or IRIG-B format to the MU through a serial port or
IEEE 1588 protocol via a network. Process bus communication using
61850 simplifies connectivity within the substation and removes the
requirement for multiple serial connections and removes the slow
serial bus architectures that are typically used. This also ensures
increased flexibility and increased speed with the use of multicast
messaging between multiple devices.

Table 6: Intra-Substation Protection requirements

3.1.1.3. Wide Area Monitoring and Control Systems

The application of synchrophasor measurement data from Phasor
Measurement Units (PMU) to Wide Area Monitoring and Control Systems
promises to provide important new capabilities for improving system
stability. Access to PMU data enables more timely situational
awareness over larger portions of the grid than what has been
possible historically with normal SCADA (Supervisory Control and Data
Acquisition) data. Handling the volume and real-time nature of
synchrophasor data presents unique challenges for existing
application architectures. Wide Area management System (WAMS) makes
it possible for the condition of the bulk power system to be observed
and understood in real-time so that protective, preventative, or
corrective action can be taken. Because of the very high sampling
rate of measurements and the strict requirement for time
synchronization of the samples, WAMS has stringent telecommunications
requirements in an IP network that are captured in the following
table:

Table 7: WAMS Special Communication Requirements

3.1.1.4. IEC 61850 WAN engineering guidelines requirement
classification

The IEC (International Electrotechnical Commission) has recently
published a Technical Report which offers guidelines on how to define
and deploy Wide Area Networks for the interconnections of electric
substations, generation plants and SCADA operation centers. The IEC
61850-90-12 is providing a classification of WAN communication
requirements into 4 classes. Table 8 summarizes these requirements:

+----------------+------------+------------+------------+-----------+
| WAN | Class WA | Class WB | Class WC | Class WD |
| Requirement | | | | |
+----------------+------------+------------+------------+-----------+
| Application | EHV (Extra | HV (High | MV (Medium | General |
| field | High | Voltage) | Voltage) | purpose |
| | Voltage) | | | |
| Latency | 5 ms | 10 ms | 100 ms | > 100 ms |
| Jitter | 10 us | 100 us | 1 ms | 10 ms |
| Latency | 100 us | 1 ms | 10 ms | 100 ms |
| Asymetry | | | | |
| Time Accuracy | 1 us | 10 us | 100 us | 10 to 100 |
| | | | | ms |
| Bit Error rate | 10-7 to | 10-5 to | 10-3 | |
| | 10-6 | 10-4 | | |
| Unavailability | 10-7 to | 10-5 to | 10-3 | |
| | 10-6 | 10-4 | | |
| Recovery delay | Zero | 50 ms | 5 s | 50 s |
| Cyber security | extremely | High | Medium | Medium |
| | high | | | |
+----------------+------------+------------+------------+-----------+

Table 8: 61850-90-12 Communication Requirements; Courtesy of IEC

3.1.2. Generation Use Case

Energy generation systems are complex infrastructures that require
control of both the generated power and the generation
infrastructure.

3.1.2.1. Control of the Generated Power

The electrical power generation frequency must be maintained within a
very narrow band. Deviations from the acceptable frequency range are
detected and the required signals are sent to the power plants for
frequency regulation.

Automatic Generation Control (AGC) is a system for adjusting the
power output of generators at different power plants, in response to
changes in the load.

Table 9: FCAG Communication Requirements

3.1.2.2. Control of the Generation Infrastructure

The control of the generation infrastructure combines requirements
from industrial automation systems and energy generation systems. In
this section we present the use case of the control of the generation
infrastructure of a wind turbine.

Figure 1: Wind Turbine Control Network

Figure 1 presents the subsystems that operate a wind turbine. These
subsystems include

o WROT (Rotor Control)

o WNAC (Nacelle Control) (nacelle: housing containing the generator)

o WTRM (Transmission Control)

o WGEN (Generator)

o WYAW (Yaw Controller) (of the tower head)

o WCNV (In-Turbine Power Converter)

o WMET (External Meteorological Station providing real time
information to the controllers of the tower)

Traffic characteristics relevant for the network planning and
dimensioning process in a wind turbine scenario are listed below.
The values in this section are based mainly on the relevant
references [Ahm14] and [Spe09]. Each logical node (Figure 1) is a
part of the metering network and produces analog measurements and
status information which must comply with their respective data rate
constraints.

+-----------+--------+--------+-------------+---------+-------------+
| Subsystem | Sensor | Analog | Data Rate | Status | Data rate |
| | Count | Sample | (bytes/sec) | Sample | (bytes/sec) |
| | | Count | | Count | |
+-----------+--------+--------+-------------+---------+-------------+
| WROT | 14 | 9 | 642 | 5 | 10 |
| WTRM | 18 | 10 | 2828 | 8 | 16 |
| WGEN | 14 | 12 | 73764 | 2 | 4 |
| WCNV | 14 | 12 | 74060 | 2 | 4 |
| WTRF | 12 | 5 | 73740 | 2 | 4 |
| WNAC | 12 | 9 | 112 | 3 | 6 |
| WYAW | 7 | 8 | 220 | 4 | 8 |
| WTOW | 4 | 1 | 8 | 3 | 6 |
| WMET | 7 | 7 | 228 | - | - |
+-----------+--------+--------+-------------+---------+-------------+

Table 10: Wind Turbine Data Rate Constraints

Quality of Service (QoS) constraints for different services are
presented in Table 11. These constraints are defined by IEEE 1646
standard [IEEE1646] and IEC 61400 standard [IEC61400].

+---------------------+---------+-------------+---------------------+
| Service | Latency | Reliability | Packet Loss Rate |
+---------------------+---------+-------------+---------------------+
| Analogue measure | 16 ms | 99.99% | < 10-6 |
| Status information | 16 ms | 99.99% | < 10-6 |
| Protection traffic | 4 ms | 100.00% | < 10-9 |
| Reporting and | 1 s | 99.99% | < 10-6 |
| logging | | | |
| Video surveillance | 1 s | 99.00% | No specific |
| | | | requirement |
| Internet connection | 60 min | 99.00% | No specific |
| | | | requirement |
| Control traffic | 16 ms | 100.00% | < 10-9 |
| Data polling | 16 ms | 99.99% | < 10-6 |
+---------------------+---------+-------------+---------------------+

Table 11: Wind Turbine Reliability and Latency Constraints

3.1.2.2.1. Intra-Domain Network Considerations

A wind turbine is composed of a large set of subsystems including
sensors and actuators which require time-critical operation. The
reliability and latency constraints of these different subsystems is
shown in Table 11. These subsystems are connected to an intra-domain
network which is used to monitor and control the operation of the
turbine and connect it to the SCADA subsystems. The different
components are interconnected using fiber optics, industrial buses,
industrial Ethernet, EtherCat, or a combination of them. Industrial
signaling and control protocols such as Modbus, Profibus, Profinet
and EtherCat are used directly on top of the Layer 2 transport or
encapsulated over TCP/IP.

The Data collected from the sensors and condition monitoring systems
is multiplexed onto fiber cables for transmission to the base of the
tower, and to remote control centers. The turbine controller
continuously monitors the condition of the wind turbine and collects
statistics on its operation. This controller also manages a large
number of switches, hydraulic pumps, valves, and motors within the
wind turbine.

There is usually a controller both at the bottom of the tower and in
the nacelle. The communication between these two controllers usually
takes place using fiber optics instead of copper links. Sometimes, a
third controller is installed in the hub of the rotor and manages the
pitch of the blades. That unit usually communicates with the nacelle
unit using serial communications.

3.1.2.2.2. Inter-Domain network considerations

A remote control center belonging to a grid operator regulates the
power output, enables remote actuation, and monitors the health of
one or more wind parks in tandem. It connects to the local control
center in a wind park over the Internet (Figure 2) via firewalls at
both ends. The AS path between the local control center and the Wind
Park typically involves several ISPs at different tiers. For
example, a remote control center in Denmark can regulate a wind park
in Greece over the normal public AS path between the two locations.

The remote control center is part of the SCADA system, setting the
desired power output to the wind park and reading back the result
once the new power output level has been set. Traffic between the
remote control center and the wind park typically consists of
protocols like IEC 60870-5-104 [IEC-60870-5-104], OPC XML-DA
[OPCXML], Modbus [MODBUS], and SNMP [RFC3411]. Currently, traffic
flows between the wind farm and the remote control center are best
effort. QoS requirements are not strict, so no SLAs or service
provisioning mechanisms (e.g., VPN) are employed. In case of events
like equipment failure, tolerance for alarm delay is on the order of
minutes, due to redundant systems already in place.

Figure 2: Wind Turbine Control via Internet

We expect future use cases which require bounded latency, bounded
jitter and extraordinary low packet loss for inter-domain traffic
flows due to the softwarization and virtualization of core wind farm
equipment (e.g. switches, firewalls and SCADA server components).
These factors will create opportunities for service providers to
install new services and dynamically manage them from remote
locations. For example, to enable fail-over of a local SCADA server,
a SCADA server in another wind farm site (under the administrative
control of the same operator) could be utilized temporarily
(Figure 3). In that case local traffic would be forwarded to the
remote SCADA server and existing intra-domain QoS and timing
parameters would have to be met for inter-domain traffic flows.

Figure 3: Wind Turbine Control via Operator Administered WAN

3.1.3. Distribution use case

3.1.3.1. Fault Location Isolation and Service Restoration (FLISR)

Fault Location, Isolation, and Service Restoration (FLISR) refers to
the ability to automatically locate the fault, isolate the fault, and
restore service in the distribution network. This will likely be the
first widespread application of distributed intelligence in the grid.

Static power switch status (open/closed) in the network dictates the
power flow to secondary substations. Reconfiguring the network in
the event of a fault is typically done manually on site to energize/
de-energize alternate paths. Automating the operation of substation
switchgear allows the flow of power to be altered automatically under
fault conditions.

FLISR can be managed centrally from a Distribution Management System
(DMS) or executed locally through distributed control via intelligent
switches and fault sensors.

Table 12: FLISR Communication Requirements

3.2. Electrical Utilities Today

Many utilities still rely on complex environments formed of multiple
application-specific proprietary networks, including TDM networks.

In this kind of environment there is no mixing of OT and IT
applications on the same network, and information is siloed between
operational areas.

Specific calibration of the full chain is required, which is costly.

This kind of environment prevents utility operations from realizing
the operational efficiency benefits, visibility, and functional
integration of operational information across grid applications and
data networks.

In addition, there are many security-related issues as discussed in
the following section.

3.2.1. Security Current Practices and Limitations

Grid monitoring and control devices are already targets for cyber
attacks, and legacy telecommunications protocols have many intrinsic
network-related vulnerabilities. For example, DNP3, Modbus,
PROFIBUS/PROFINET, and other protocols are designed around a common
paradigm of request and respond. Each protocol is designed for a
master device such as an HMI (Human Machine Interface) system to send
commands to subordinate slave devices to retrieve data (reading
inputs) or control (writing to outputs). Because many of these
protocols lack authentication, encryption, or other basic security
measures, they are prone to network-based attacks, allowing a
malicious actor or attacker to utilize the request-and-respond system
as a mechanism for command-and-control like functionality. Specific
security concerns common to most industrial control, including
utility telecommunication protocols include the following:

o Network or transport errors (e.g. malformed packets or excessive
latency) can cause protocol failure.

o Protocol commands may be available that are capable of forcing
slave devices into inoperable states, including powering-off
devices, forcing them into a listen-only state, disabling
alarming.

o Protocol commands may be available that are capable of restarting
communications and otherwise interrupting processes.

o Protocol commands may be available that are capable of clearing,
erasing, or resetting diagnostic information such as counters and
diagnostic registers.

o Protocol commands may be available that are capable of requesting
sensitive information about the controllers, their configurations,
or other need-to-know information.

o Most protocols are application layer protocols transported over
TCP; therefore it is easy to transport commands over non-standard
ports or inject commands into authorized traffic flows.

o Protocol commands may be available that are capable of
broadcasting messages to many devices at once (i.e. a potential
DoS).

o Protocol commands may be available to query the device network to
obtain defined points and their values (i.e. a configuration
scan).

o Protocol commands may be available that will list all available
function codes (i.e. a function scan).

These inherent vulnerabilities, along with increasing connectivity
between IT an OT networks, make network-based attacks very feasible.

Simple injection of malicious protocol commands provides control over
the target process. Altering legitimate protocol traffic can also
alter information about a process and disrupt the legitimate controls
that are in place over that process. A man-in-the-middle attack
could provide both control over a process and misrepresentation of
data back to operator consoles.

3.3. Electrical Utilities Future

The business and technology trends that are sweeping the utility
industry will drastically transform the utility business from the way
it has been for many decades. At the core of many of these changes
is a drive to modernize the electrical grid with an integrated
telecommunications infrastructure. However, interoperability
concerns, legacy networks, disparate tools, and stringent security
requirements all add complexity to the grid transformation. Given
the range and diversity of the requirements that should be addressed
by the next generation telecommunications infrastructure, utilities
need to adopt a holistic architectural approach to integrate the
electrical grid with digital telecommunications across the entire
power delivery chain.

The key to modernizing grid telecommunications is to provide a
common, adaptable, multi-service network infrastructure for the
entire utility organization. Such a network serves as the platform
for current capabilities while enabling future expansion of the
network to accommodate new applications and services.

To meet this diverse set of requirements, both today and in the
future, the next generation utility telecommunnications network will
be based on open-standards-based IP architecture. An end-to-end IP
architecture takes advantage of nearly three decades of IP technology
development, facilitating interoperability and device management
across disparate networks and devices, as it has been already
demonstrated in many mission-critical and highly secure networks.

IPv6 is seen as a future telecommunications technology for the Smart
Grid; the IEC (International Electrotechnical Commission) and
different National Committees have mandated a specific adhoc group
(AHG8) to define the migration strategy to IPv6 for all the IEC TC57
power automation standards.

We expect cloud-based SCADA systems to control and monitor the
critical and non-critical subsystems of generation systems, for
example wind farms.

3.3.1. Migration to Packet-Switched Network

Throughout the world, utilities are increasingly planning for a
future based on smart grid applications requiring advanced
telecommunications systems. Many of these applications utilize
packet connectivity for communicating information and control signals
across the utility's Wide Area Network (WAN), made possible by
technologies such as multiprotocol label switching (MPLS). The data
that traverses the utility WAN includes:

o Grid monitoring, control, and protection data

o Non-control grid data (e.g. asset data for condition-based
monitoring)

o Physical safety and security data (e.g. voice and video)

o Remote worker access to corporate applications (voice, maps,
schematics, etc.)

o Field area network backhaul for smart metering, and distribution
grid management

o Enterprise traffic (email, collaboration tools, business
applications)

WANs support this wide variety of traffic to and from substations,
the transmission and distribution grid, generation sites, between
control centers, and between work locations and data centers. To
maintain this rapidly expanding set of applications, many utilities
are taking steps to evolve present time-division multiplexing (TDM)
based and frame relay infrastructures to packet systems. Packet-
based networks are designed to provide greater functionalities and
higher levels of service for applications, while continuing to
deliver reliability and deterministic (real-time) traffic support.

3.3.2. Telecommunications Trends

These general telecommunications topics are in addition to the use
cases that have been addressed so far. These include both current
and future telecommunications related topics that should be factored
into the network architecture and design.

3.3.2.1. General Telecommunications Requirements

o IP Connectivity everywhere

o Monitoring services everywhere and from different remote centers
o Move services to a virtual data center

o Unify access to applications / information from the corporate
network

o Unify services

o Unified Communications Solutions

o Mix of fiber and microwave technologies - obsolescence of SONET/
SDH or TDM

o Standardize grid telecommunications protocol to opened standard to
ensure interoperability

o Reliable Telecommunications for Transmission and Distribution
Substations

o IEEE 1588 time synchronization Client / Server Capabilities

o Integration of Multicast Design

o QoS Requirements Mapping

o Enable Future Network Expansion

o Substation Network Resilience

o Fast Convergence Design

o Scalable Headend Design

o Define Service Level Agreements (SLA) and Enable SLA Monitoring

o Integration of 3G/4G Technologies and future technologies

o Ethernet Connectivity for Station Bus Architecture

o Ethernet Connectivity for Process Bus Architecture

o Protection, teleprotection and PMU (Phaser Measurement Unit) on IP

3.3.2.2. Specific Network topologies of Smart Grid Applications

Utilities often have very large private telecommunications networks.
It covers an entire territory / country. The main purpose of the
network, until now, has been to support transmission network
monitoring, control, and automation, remote control of generation
sites, and providing FCAPS (Fault, Configuration, Accounting,
Performance, Security) services from centralized network operation
centers.

Going forward, one network will support operation and maintenance of
electrical networks (generation, transmission, and distribution),
voice and data services for ten of thousands of employees and for
exchange with neighboring interconnections, and administrative
services. To meet those requirements, utility may deploy several
physical networks leveraging different technologies across the
country: an optical network and a microwave network for instance.
Each protection and automatism system between two points has two
telecommunications circuits, one on each network. Path diversity
between two substations is key. Regardless of the event type
(hurricane, ice storm, etc.), one path shall stay available so the
system can still operate.

In the optical network, signals are transmitted over more than tens
of thousands of circuits using fiber optic links, microwave and
telephone cables. This network is the nervous system of the
utility's power transmission operations. The optical network
represents ten of thousands of km of cable deployed along the power
lines, with individual runs as long as 280 km.

3.3.2.3. Precision Time Protocol

Some utilities do not use GPS clocks in generation substations. One
of the main reasons is that some of the generation plants are 30 to
50 meters deep under ground and the GPS signal can be weak and
unreliable. Instead, atomic clocks are used. Clocks are
synchronized amongst each other. Rubidium clocks provide clock and
1ms timestamps for IRIG-B.

Some companies plan to transition to the Precision Time Protocol
(PTP, [IEEE1588]), distributing the synchronization signal over the
IP/MPLS network. PTP provides a mechanism for synchronizing the
clocks of participating nodes to a high degree of accuracy and
precision.

PTP operates based on the following assumptions:

It is assumed that the network eliminates cyclic forwarding of PTP
messages within each communication path (e.g. by using a spanning
tree protocol).

PTP is tolerant of an occasional missed message, duplicated
message, or message that arrived out of order. However, PTP
assumes that such impairments are relatively rare.

PTP was designed assuming a multicast communication model, however
PTP also supports a unicast communication model as long as the
behavior of the protocol is preserved.

Like all message-based time transfer protocols, PTP time accuracy
is degraded by delay asymmetry in the paths taken by event
messages. Asymmetry is not detectable by PTP, however, if such
delays are known a priori, PTP can correct for asymmetry.

IEC 61850 will recommend the use of the IEEE PTP 1588 Utility Profile
(as defined in [IEC62439-3:2012] Annex B) which offers the support of
redundant attachment of clocks to Parallel Redundancy Protcol (PRP)
and High-availability Seamless Redundancy (HSR) networks.

3.3.3. Security Trends in Utility Networks

Although advanced telecommunications networks can assist in
transforming the energy industry by playing a critical role in
maintaining high levels of reliability, performance, and
manageability, they also introduce the need for an integrated
security infrastructure. Many of the technologies being deployed to
support smart grid projects such as smart meters and sensors can
increase the vulnerability of the grid to attack. Top security
concerns for utilities migrating to an intelligent smart grid
telecommunications platform center on the following trends:

o Integration of distributed energy resources

o Proliferation of digital devices to enable management, automation,
protection, and control

o Regulatory mandates to comply with standards for critical
infrastructure protection

o Migration to new systems for outage management, distribution
automation, condition-based maintenance, load forecasting, and
smart metering

o Demand for new levels of customer service and energy management

This development of a diverse set of networks to support the
integration of microgrids, open-access energy competition, and the
use of network-controlled devices is driving the need for a converged
security infrastructure for all participants in the smart grid,
including utilities, energy service providers, large commercial and
industrial, as well as residential customers. Securing the assets of
electric power delivery systems (from the control center to the
substation, to the feeders and down to customer meters) requires an
end-to-end security infrastructure that protects the myriad of
telecommunications assets used to operate, monitor, and control power
flow and measurement.

"Cyber security" refers to all the security issues in automation and
telecommunications that affect any functions related to the operation
of the electric power systems. Specifically, it involves the
concepts of:

o Integrity : data cannot be altered undetectably

o Authenticity : the telecommunications parties involved must be
validated as genuine

o Authorization : only requests and commands from the authorized
users can be accepted by the system

o Confidentiality : data must not be accessible to any
unauthenticated users

When designing and deploying new smart grid devices and
telecommunications systems, it is imperative to understand the
various impacts of these new components under a variety of attack
situations on the power grid. Consequences of a cyber attack on the
grid telecommunications network can be catastrophic. This is why
security for smart grid is not just an ad hoc feature or product,
it's a complete framework integrating both physical and Cyber
security requirements and covering the entire smart grid networks
from generation to distribution. Security has therefore become one
of the main foundations of the utility telecom network architecture
and must be considered at every layer with a defense-in-depth
approach. Migrating to IP based protocols is key to address these
challenges for two reasons:

o IP enables a rich set of features and capabilities to enhance the
security posture

o IP is based on open standards, which allows interoperability
between different vendors and products, driving down the costs
associated with implementing security solutions in OT networks.

Securing OT (Operation technology) telecommunications over packet-
switched IP networks follow the same principles that are foundational
for securing the IT infrastructure, i.e., consideration must be given
to enforcing electronic access control for both person-to-machine and
machine-to-machine communications, and providing the appropriate
levels of data privacy, device and platform integrity, and threat
detection and mitigation.

3.4. Electrical Utilities Asks

o Mixed L2 and L3 topologies

o Deterministic behavior

o Bounded latency and jitter

o Tight feedback intervals

o High availability, low recovery time

o Redundancy, low packet loss

o Precise timing

o Centralized computing of deterministic paths

o Distributed configuration may also be useful

4. Building Automation Systems

4.1. Use Case Description

A Building Automation System (BAS) manages equipment and sensors in a
building for improving residents' comfort, reducing energy
consumption, and responding to failures and emergencies. For
example, the BAS measures the temperature of a room using sensors and
then controls the HVAC (heating, ventilating, and air conditioning)
to maintain a set temperature and minimize energy consumption.

A BAS primarily performs the following functions:

o Periodically measures states of devices, for example humidity and
illuminance of rooms, open/close state of doors, FAN speed, etc.

o Stores the measured data.

o Provides the measured data to BAS systems and operators.

o Generates alarms for abnormal state of devices.

o Controls devices (e.g. turn off room lights at 10:00 PM).

4.2. Building Automation Systems Today

4.2.1. BAS Architecture

A typical BAS architecture of today is shown in Figure 4.

+----------------------------+
| |
| BMS HMI |
| | | |
| +----------------------+ |
| | Management Network | |
| +----------------------+ |
| | | |
| LC LC |
| | | |
| +----------------------+ |
| | Field Network | |
| +----------------------+ |
| | | | | |
| Dev Dev Dev Dev |
| |
+----------------------------+

BMS := Building Management Server
HMI := Human Machine Interface
LC := Local Controller

Figure 4: BAS architecture

There are typically two layers of network in a BAS. The upper one is
called the Management Network and the lower one is called the Field
Network. In management networks an IP-based communication protocol
is used, while in field networks non-IP based communication protocols
("field protocols") are mainly used. Field networks have specific
timing requirements, whereas management networks can be best-effort.

A Human Machine Interface (HMI) is typically a desktop PC used by
operators to monitor and display device states, send device control
commands to Local Controllers (LCs), and configure building schedules
(for example "turn off all room lights in the building at 10:00 PM").

A Building Management Server (BMS) performs the following operations.

o Collect and store device states from LCs at regular intervals.

o Send control values to LCs according to a building schedule.

o Send an alarm signal to operators if it detects abnormal devices
states.

The BMS and HMI communicate with LCs via IP-based "management
protocols" (see standards [bacnetip], [knx]).

A LC is typically a Programmable Logic Controller (PLC) which is
connected to several tens or hundreds of devices using "field
protocols". An LC performs the following kinds of operations:

o Measure device states and provide the information to BMS or HMI.

o Send control values to devices, unilaterally or as part of a
feedback control loop.

There are many field protocols used today; some are standards-based
and others are proprietary (see standards [lontalk], [modbus],
[profibus] and [flnet]). The result is that BASs have multiple MAC/
PHY modules and interfaces. This makes BASs more expensive, slower
to develop, and can result in "vendor lock-in" with multiple types of
management applications.

4.2.2. BAS Deployment Model

An example BAS for medium or large buildings is shown in Figure 5.
The physical layout spans multiple floors, and there is a monitoring
room where the BAS management entities are located. Each floor will
have one or more LCs depending upon the number of devices connected
to the field network.

+--------------------------------------------------+
| Floor 3 |
| +----LC~~~~+~~~~~+~~~~~+ |
| | | | | |
| | Dev Dev Dev |
| | |
|--- | ------------------------------------------|
| | Floor 2 |
| +----LC~~~~+~~~~~+~~~~~+ Field Network |
| | | | | |
| | Dev Dev Dev |
| | |
|--- | ------------------------------------------|
| | Floor 1 |
| +----LC~~~~+~~~~~+~~~~~+ +-----------------|
| | | | | | Monitoring Room |
| | Dev Dev Dev | |
| | | BMS HMI |
| | Management Network | | | |
| +--------------------------------+-----+ |
| | |
+--------------------------------------------------+

Figure 5: BAS Deployment model for Medium/Large Buildings

Each LC is connected to the monitoring room via the Management
network, and the management functions are performed within the
building. In most cases, fast Ethernet (e.g. 100BASE-T) is used for
the management network. Since the management network is non-
realtime, use of Ethernet without quality of service is sufficient
for today's deployment.

In the field network a variety of physical interfaces such as RS232C
and RS485 are used, which have specific timing requirements. Thus if
a field network is to be replaced with an Ethernet or wireless
network, such networks must support time-critical deterministic
flows.

In Figure 6, another deployment model is presented in which the
management system is hosted remotely. This is becoming popular for
small office and residential buildings in which a standalone
monitoring system is not cost-effective.

+---------------+
| Remote Center |
| |
| BMS HMI |
+------------------------------------+ | | | |
| Floor 2 | | +---+---+ |
| +----LC~~~~+~~~~~+ Field Network| | | |
| | | | | | Router |
| | Dev Dev | +-------|-------+
| | | |
|--- | ------------------------------| |
| | Floor 1 | |
| +----LC~~~~+~~~~~+ | |
| | | | | |
| | Dev Dev | |
| | | |
| | Management Network | WAN |
| +------------------------Router-------------+
| |
+------------------------------------+

Figure 6: Deployment model for Small Buildings

Some interoperability is possible today in the Management Network,
but not in today's field networks due to their non-IP-based design.

4.2.3. Use Cases for Field Networks

Below are use cases for Environmental Monitoring, Fire Detection, and
Feedback Control, and their implications for field network
performance.

4.2.3.1. Environmental Monitoring

The BMS polls each LC at a maximum measurement interval of 100ms (for
example to draw a historical chart of 1 second granularity with a 10x
sampling interval) and then performs the operations as specified by
the operator. Each LC needs to measure each of its several hundred
sensors once per measurement interval. Latency is not critical in
this scenario as long as all sensor values are completed in the
measurement interval. Availability is expected to be 99.999 %.

4.2.3.2. Fire Detection

On detection of a fire, the BMS must stop the HVAC, close the fire
shutters, turn on the fire sprinklers, send an alarm, etc. There are
typically ~10s of sensors per LC that BMS needs to manage. In this
scenario the measurement interval is 10-50ms, the communication delay
is 10ms, and the availability must be 99.9999 %.

4.2.3.3. Feedback Control

BAS systems utilize feedback control in various ways; the most time-
critial is control of DC motors, which require a short feedback
interval (1-5ms) with low communication delay (10ms) and jitter
(1ms). The feedback interval depends on the characteristics of the
device and a target quality of control value. There are typically
~10s of such devices per LC.

Communication delay is expected to be less than 10 ms, jitter less
than 1 sec while the availability must be 99.9999% .

4.2.4. Security Considerations

When BAS field networks were developed it was assumed that the field
networks would always be physically isolated from external networks
and therefore security was not a concern. In today's world many BASs
are managed remotely and are thus connected to shared IP networks and
so security is definitely a concern, yet security features are not
available in the majority of BAS field network deployments .

The management network, being an IP-based network, has the protocols
available to enable network security, but in practice many BAS
systems do not implement even the available security features such as
device authentication or encryption for data in transit.

4.3. BAS Future

In the future we expect more fine-grained environmental monitoring
and lower energy consumption, which will require more sensors and
devices, thus requiring larger and more complex building networks.

We expect building networks to be connected to or converged with
other networks (Enterprise network, Home network, and Internet).

Therefore better facilities for network management, control,
reliability and security are critical in order to improve resident
and operator convenience and comfort. For example the ability to
monitor and control building devices via the internet would enable
(for example) control of room lights or HVAC from a resident's
desktop PC or phone application.

4.4. BAS Asks

The community would like to see an interoperable protocol
specification that can satisfy the timing, security, availability and
QoS constraints described above, such that the resulting converged
network can replace the disparate field networks. Ideally this
connectivity could extend to the open Internet.

This would imply an architecture that can guarantee

o Low communication delays (from <10ms to 100ms in a network of
several hundred devices)

o Low jitter (< 1 ms)

o Tight feedback intervals (1ms - 10ms)

o High network availability (up to 99.9999% )

o Availability of network data in disaster scenario

o Authentication between management and field devices (both local
and remote)

o Integrity and data origin authentication of communication data
between field and management devices

o Confidentiality of data when communicated to a remote device

5. Wireless for Industrial

5.1. Use Case Description

Wireless networks are useful for industrial applications, for example
when portable, fast-moving or rotating objects are involved, and for
the resource-constrained devices found in the Internet of Things
(IoT).

Such network-connected sensors, actuators, control loops (etc.)
typically require that the underlying network support real-time
quality of service (QoS), as well as specific classes of other
network properties such as reliability, redundancy, and security.

These networks may also contain very large numbers of devices, for
example for factories, "big data" acquisition, and the IoT. Given
the large numbers of devices installed, and the potential
pervasiveness of the IoT, this is a huge and very cost-sensitive
market. For example, a 1% cost reduction in some areas could save
$100B

5.1.1. Network Convergence using 6TiSCH

Some wireless network technologies support real-time QoS, and are
thus useful for these kinds of networks, but others do not. For
example WiFi is pervasive but does not provide guaranteed timing or
delivery of packets, and thus is not useful in this context.

In this use case we focus on one specific wireless network technology
which does provide the required deterministic QoS, which is "IPv6
over the TSCH mode of IEEE 802.15.4e" (6TiSCH, where TSCH stands for
"Time-Slotted Channel Hopping", see [I-D.ietf-6tisch-architecture],
[IEEE802154], [IEEE802154e], and [RFC7554]).

There are other deterministic wireless busses and networks available
today, however they are imcompatible with each other, and
incompatible with IP traffic (for example [ISA100], [WirelessHART]).

Thus the primary goal of this use case is to apply 6TiSH as a
converged IP- and standards-based wireless network for industrial
applications, i.e. to replace multiple proprietary and/or
incompatible wireless networking and wireless network management
standards.

5.1.2. Common Protocol Development for 6TiSCH

Today there are a number of protocols required by 6TiSCH which are
still in development, and a second intent of this use case is to
highlight the ways in which these "missing" protocols share goals in
common with DetNet. Thus it is possible that some of the protocol
technology developed for DetNet will also be applicable to 6TiSCH.

These protocol goals are identified here, along with their
relationship to DetNet. It is likely that ultimately the resulting
protocols will not be identical, but will share design principles
which contribute to the eficiency of enabling both DetNet and 6TiSCH.

One such commonality is that although at a different time scale, in
both TSN [IEEE802.1TSNTG] and TSCH a packet crosses the network from
node to node follows a precise schedule, as a train that leaves
intermediate stations at precise times along its path. This kind of
operation reduces collisions, saves energy, and enables engineering
the network for deterministic properties.

Another commonality is remote monitoring and scheduling management of
a TSCH network by a Path Computation Element (PCE) and Network
Management Entity (NME). The PCE/NME manage timeslots and device
resources in a manner that minimizes the interaction with and the
load placed on resource-constrained devices. For example, a tiny IoT
device may have just enough buffers to store one or a few IPv6
packets, and will have limited bandwidth between peers such that it
can maintain only a small amount of peer information, and will not be
able to store many packets waiting to be forwarded. It is
advantageous then for it to only be required to carry out the
specific behavior assigned to it by the PCE/NME (as opposed to
maintaining its own IP stack, for example).

Note: Current WG discussion indicates that some peer-to-peer
communication must be assumed, i.e. the PCE may communicate only
indirectly with any given device, enabling hierarchical configuration
of the system.

6TiSCH depends on [PCE] and [I-D.finn-detnet-architecture].

6TiSCH also depends on the fact that DetNet will maintain consistency
with [IEEE802.1TSNTG].

5.2. Wireless Industrial Today

Today industrial wireless is accomplished using multiple
deterministic wireless networks which are incompatible with each
other and with IP traffic.

6TiSCH is not yet fully specified, so it cannot be used in today's
applications.

5.3. Wireless Industrial Future

5.3.1. Unified Wireless Network and Management

We expect DetNet and 6TiSCH together to enable converged transport of
deterministic and best-effort traffic flows between real-time
industrial devices and wide area networks via IP routing. A high
level view of a basic such network is shown in Figure 7.

---+-------- ............ ------------
| External Network External Network |
| +-----+
+-----+ | NME |
| | LLN Border | |
| | router +-----+
+-----+
o o o
o o o o
o o LLN o o o
o o o o
o

Figure 7: Basic 6TiSCH Network

Figure 8 shows a backbone router federating multiple synchronized
6TiSCH subnets into a single subnet connected to the external
network.

---+-------- ............ ------------
| External Network |
| +-----+
| +-----+ | NME |
+-----+ | +-----+ | |
| | Router | | PCE | +-----+
| | +--| |
+-----+ +-----+
| |
| Subnet Backbone |
+--------------------+------------------+
| | |
+-----+ +-----+ +-----+
| | Backbone | | Backbone | | Backbone
o | | router | | router | | router
+-----+ +-----+ +-----+
o o o o o
o o o o o o o o o o o
o o o LLN o o o o
o o o o o o o o o o o o

Figure 8: Extended 6TiSCH Network

The backbone router must ensure end-to-end deterministic behavior
between the LLN and the backbone. We would like to see this
accomplished in conformance with the work done in
[I-D.finn-detnet-architecture] with respect to Layer-3 aspects of
deterministic networks that span multiple Layer-2 domains.

The PCE must compute a deterministic path end-to-end across the TSCH
network and IEEE802.1 TSN Ethernet backbone, and DetNet protocols are
expected to enable end-to-end deterministic forwarding.

+-----+
| IoT |
| G/W |
+-----+
+-----+
^ <---- Elimination
| NME |
Track branch | |
+-------+ +--------+ Subnet Backbone
| LLN Border |
+--|--+ +--|--+
| | | router +-----+
+-----+
o Backbone | | | Backbone
o | | | router | | | router
+--/--+ +--|--+
o / o o---o----/ o
o o---o--/ o o o LLN o o
o \ / o o LLN o
o v <---- Replication
o

Figure 7: Basic 9: 6TiSCH Network with PRE

5.3.1.1. PCE and 6TiSCH ARQ Retries

Note: The possible use of ARQ techniques in DetNet is currently
considered a possible design alternative.

6TiSCH uses the IEEE802.15.4 Automatic Repeat-reQuest (ARQ) mechanism
to provide higher reliability of packet delivery. ARQ is related to
packet replication and elimination because there are two independent
paths for packets to arrive at the destination, and if an expected
packed does not arrive on one path then it checks for the packet on
the second path.

Although to date this mechanism is only used by wireless networks,
this may be a technique that would be appropriate for DetNet and so
aspects of the enabling protocol could be co-developed.

For example, in Figure 8 shows 9, a Track is laid out from a field device in
a 6TiSCH network to an IoT gateway that is located on a IEEE802.1 TSN
backbone.

In ARQ the Replication function in the field device sends a copy of
each packet over two different branches, and the PCE schedules each
hop of both branches so that the two copies arrive in due time at the
gateway. In case of a backbone router federating multiple synchronized loss on one branch, hopefully the other copy
of the packet still arrives within the allocated time. If two copies
make it to the IoT gateway, the Elimination function in the gateway
ignores the extra packet and presents only one copy to upper layers.

At each 6TiSCH subnets into hop along the Track, the PCE may schedule more than
one timeSlot for a single subnet connected packet, so as to support Layer-2 retries (ARQ).

In current deployments, a TSCH Track does not necessarily support PRE
but is systematically multi-path. This means that a Track is
scheduled so as to ensure that each hop has at least two forwarding
solutions, and the external
network.

---+-------- ............ ------------
| External Network |
| +-----+
| +-----+ | NME |
+-----+ | +-----+ | |
| | Router | | forwarding decision is to try the preferred one
and use the other in case of Layer-2 transmission failure as detected
by ARQ.

Figure 8: Extended

A common feature of 6TiSCH Network

The backbone router must ensure end-to-end deterministic behavior
between and DetNet is the LLN action of a PCE to
configure paths through the network. Specifically, what is needed is
a protocol and data model that the backbone. We would like PCE will use to see get/set the
relevant configuration from/to the devices, as well as perform
operations on the devices. We expect that this
accomplished in conformance protocol will be
developed by DetNet with consideration for its reuse by 6TiSCH. The
remainder of this section provides a bit more context from the work done in
[I-D.finn-detnet-architecture] with respect 6TiSCH
side.

5.3.2.1. PCE Commands and 6TiSCH CoAP Requests

The 6TiSCH device does not expect to Layer-3 aspects place the request for bandwidth
between itself and another device in the network. Rather, an
operation control system invoked through a human interface specifies
the required traffic specification and the end nodes (in terms of
deterministic networks that span multiple Layer-2 domains.

The
latency and reliability). Based on this information, the PCE must
compute a deterministic path end-to-end across between the TSCH
network and IEEE802.1 TSN Ethernet backbone, end nodes and DetNet protocols are
expected to enable end-to-end deterministic forwarding.

+-----+
| IoT |
| G/W |
+-----+
^ <---- Elimination
| |
Track branch | |
+-------+ +--------+ Subnet Backbone
| |
+--|--+ +--|--+
| | | Backbone | | | Backbone
o | | | router | | | router
+--/--+ +--|--+
o / o o---o----/ o
o o---o--/ o o o o o
o \ / o o LLN o
o v <---- Replication
o

Figure 9: 6TiSCH Network provision the network with PRE

5.3.1.1. PCE
per-flow state that describes the per-hop operation for a given
packet, the corresponding timeslots, and 6TiSCH ARQ Retries

Note: The possible use the flow identification that
enables recognizing that a certain packet belongs to a certain path,
etc.

For a static configuration that serves a certain purpose for a long
period of ARQ techniques in DetNet time, it is currently
considered expected that a possible design alternative. node will be provisioned in one
shot with a full schedule, which incorporates the aggregation of its
behavior for multiple paths. 6TiSCH uses expects that the IEEE802.15.4 Automatic Repeat-reQuest (ARQ) mechanism
to provide higher reliability programing of packet delivery. ARQ is related to
packet replication
the schedule will be done over COAP as discussed in
[I-D.ietf-6tisch-coap].

6TiSCH expects that the PCE commands will be mapped back and elimination because there are two independent
paths for packets to arrive forth
into CoAP by a gateway function at the destination, and if an expected
packed does not arrive on one path then it checks for edge of the packet 6TiSCH network.
For instance, it is possible that a mapping entity on the second path.

Although backbone
transforms a non-CoAP protocol such as PCEP into the RESTful
interfaces that the 6TiSCH devices support. This architecture will
be refined to date this mechanism comply with DetNet [I-D.finn-detnet-architecture] when
the work is only used by wireless networks,
this formalized. Related information about 6TiSCH can be
found at [I-D.ietf-6tisch-6top-interface] and RPL [RFC6550].

A protocol may be used to update the state in the devices during
runtime, for example if it appears that a technique path through the network
has ceased to perform as expected, but in 6TiSCH that flow was not
designed and no protocol was selected. We would be appropriate for like to see DetNet and so
aspects of
define the enabling protocol could appropriate end-to-end protocols to be co-developed.

For example, in Figure 9, a Track is laid out from a field device used in
a 6TiSCH network to an IoT gateway that case.
The implication is located on a IEEE802.1 TSN
backbone.

In ARQ that these state updates take place once the Replication function in
system is configured and running, i.e. they are not limited to the field device sends a copy
initial communication of
each packet over two different branches, and the PCE schedules each
hop configuration of both branches so that the two copies arrive in due time at system.

A "slotFrame" is the
gateway. In case of base object that a loss on one branch, hopefully PCE would manipulate to
program a schedule into an LLN node ([I-D.ietf-6tisch-architecture]).

We would like to see the other copy
of PCE read energy data from devices, and
compute paths that will implement policies on how energy in devices
is consumed, for instance to ensure that the packet still arrives within spent energy does not
exceeded the allocated available energy over a period of time. If two copies
make it Note: this
statement implies that an extensible protocol for communicating
device info to the IoT gateway, PCE and enabling the Elimination function in PCE to act on it will be part
of the DetNet architecture, however for subnets with specific
protocols (e.g. CoAP) a gateway
ignores the extra packet and presents only one copy to upper layers.

At each may be required.

6TiSCH hop along the Track, devices can discover their neighbors over the PCE may schedule more than
one timeSlot for radio using a packet, so
mechanism such as to support Layer-2 retries (ARQ).

In current deployments, a TSCH Track does not necessarily support PRE beacons, but even though the neighbor information
is systematically multi-path. This means that available in the 6TiSCH interface data model, 6TiSCH does not
describe a Track is
scheduled so as protocol to ensure that each hop has at least two forwarding
solutions, and proactively push the forwarding decision is neighborhood information
to try the preferred one
and use the other in case of Layer-2 transmission failure as detected
by ARQ.

5.3.2. Schedule Management by a PCE

A common feature of 6TiSCH and PCE. We would like to see DetNet define such a protocol; one
possible design alternative is the action of that it could operate over CoAP,
alternatively it could be converted to/from CoAP by a PCE gateway. We
would like to
configure paths through the network. Specifically, what is needed is see such a protocol carry multiple metrics, for example
similar to those used for RPL operations [RFC6551]

5.3.2.2. 6TiSCH IP Interface

"6top" ([I-D.wang-6tisch-6top-sublayer]) is a logical link control
sitting between the IP layer and the TSCH MAC layer which provides
the link abstraction that is required for IP operations. The 6top
data model and management interfaces are further discussed in
[I-D.ietf-6tisch-6top-interface] and [I-D.ietf-6tisch-coap].

An IP packet that is sent along a 6TiSCH path uses the PCE will use to get/set the
relevant configuration from/to Differentiated
Services Per-Hop-Behavior Group called Deterministic Forwarding, as
described in [I-D.svshah-tsvwg-deterministic-forwarding].

5.3.3. 6TiSCH Security Considerations

On top of the devices, as well as perform
operations classical requirements for protection of control
signaling, it must be noted that 6TiSCH networks operate on the devices. We expect limited
resources that this protocol will can be
developed by DetNet with consideration depleted rapidly in a DoS attack on the system,
for its reuse instance by 6TiSCH. The
remainder of this section provides placing a bit more context from rogue device in the 6TiSCH
side.

5.3.2.1. PCE Commands network, or by
obtaining management control and setting up unexpected additional
paths.

5.4. Wireless Industrial Asks

6TiSCH CoAP Requests

The 6TiSCH device does not expect depends on DetNet to place the request define:

o Configuration (state) and operations for bandwidth
between itself deterministic paths

o End-to-end protocols for deterministic forwarding (tagging, IP)

o Protocol for packet replication and another device in elimination

6. Cellular Radio

6.1. Use Case Description

This use case describes the network. Rather, an
operation control system invoked through a human interface specifies application of deterministic networking
in the required traffic specification context of cellular telecom transport networks. Important
elements include time synchronization, clock distribution, and the end nodes (in terms ways
of
latency establishing time-sensitive streams for both Layer-2 and reliability). Based on this information, the PCE must
compute Layer-3
user plane traffic.

6.1.1. Network Architecture

Figure 10 illustrates a path between the end nodes typical 3GPP-defined cellular network
architecture, which includes "Fronthaul" and provision "Midhaul" network
segments. The "Fronthaul" is the network connecting base stations
(baseband processing units) to the remote radio heads (antennas).
The "Midhaul" is the network inter-connecting base stations (or small
cell sites).

In Figure 10 "eNB" ("E-UTRAN Node B") is the network with
per-flow state hardware that describes is
connected to the per-hop operation mobile phone network which communicates directly
with mobile handsets ([TS36300]).

Y (remote radio heads (antennas))
\
Y__ \.--. .--. +------+
\_( `. +---+ _(Back`. | 3GPP |
Y------( Front )----|eNB|----( Haul )----| core |
( ` .Haul ) +---+ ( ` . ) ) | netw |
/`--(___.-' \ `--(___.-' +------+
Y_/ / \.--. \
Y_/ _( Mid`. \
( Haul ) \
( ` . ) ) \
`--(___.-'\_____+---+ (small cell sites)
\ |SCe|__Y
+---+ +---+
Y__|eNB|__Y
+---+
Y_/ \_Y ("local" radios)

Figure 10: Generic 3GPP-based Cellular Network Architecture

6.1.2. Delay Constraints

The available processing time for a given
packet, Fronthaul networking overhead is
limited to the corresponding timeslots, and available time after the flow identification that
enables recognizing that a certain packet belongs to a certain path,
etc. baseband processing of the
radio frame has completed. For a static configuration that serves a certain purpose for a long
period example in Long Term Evolution (LTE)
radio, processing of time, it a radio frame is expected that allocated 3ms but typically the
processing uses most of it, allowing only a node will small fraction to be provisioned in one
shot with a full schedule, which incorporates used
by the aggregation of its
behavior for multiple paths. 6TiSCH expects that Fronthaul network (e.g. up to 250us one-way delay, though the programing of
existing spec ([NGMN-fronth]) supports delay only up to 100us). This
ultimately determines the schedule will be done over COAP as discussed in
[I-D.ietf-6tisch-coap].

6TiSCH expects that distance the PCE commands will remote radio heads can be mapped back and forth
into CoAP by a gateway function at
located from the edge base stations (e.g., 100us equals roughly 20 km of
optical fiber-based transport). Allocation options of the 6TiSCH network. available
time budget between processing and transport are under heavy
discussions in the mobile industry.

For instance, it is possible that a mapping entity on packet-based transport the backbone
transforms a non-CoAP protocol such as PCEP into allocated transport time (e.g. CPRI
would allow for 100us delay [CPRI]) is consumed by all nodes and
buffering between the RESTful
interfaces that remote radio head and the 6TiSCH devices support. This architecture will
be refined to comply with DetNet [I-D.finn-detnet-architecture] when baseband processing
unit, plus the work is formalized. Related information about 6TiSCH can be
found at [I-D.ietf-6tisch-6top-interface] distance-incurred delay.

The baseband processing time and RPL [RFC6550].

A protocol may be used to update the state in the devices during
runtime, available "delay budget" for example if it appears that a path through the network
has ceased
fronthaul is likely to perform as expected, but change in 6TiSCH that flow was not
designed and no protocol was selected. We would like to see DetNet
define the appropriate end-to-end protocols forthcoming "5G" due to be used in that case.
The implication is that these state updates take place once reduced
radio round trip times and other architectural and service
requirements [NGMN].

[METIS] documents the fundamental challenges as well as overall
technical goals of the future 5G mobile and wireless system is configured as the
starting point. These future systems should support much higher data
volumes and rates and significantly lower end-to-end latency for 100x
more connected devices (at similar cost and running, i.e. they energy consumption levels
as today's system).

For Midhaul connections, delay constraints are not limited to the
initial communication of the configuration of the system.

A "slotFrame" is the base object that a PCE would manipulate to
program a schedule into an LLN node ([I-D.ietf-6tisch-architecture]).

We would driven by Inter-Site
radio functions like to Coordinated Multipoint Processing (CoMP, see the PCE read energy data from devices,
[CoMP]). CoMP reception and
compute paths that will implement policies on how energy in devices transmission is consumed, for instance a framework in which
multiple geographically distributed antenna nodes cooperate to ensure that
improve the spent energy does not
exceeded performance of the available energy over a period users served in the common cooperation
area. The design principal of time. Note: this
statement implies that an extensible protocol for communicating
device info CoMP is to extend the PCE and enabling the PCE current single-
cell to act on it will be part multi-UE (User Equipment) transmission to a multi-cell-to-
multi-UEs transmission by base station cooperation.

CoMP has delay-sensitive performance parameters, which are "midhaul
latency" and "CSI (Channel State Information) reporting and
accuracy". The essential feature of CoMP is signaling between eNBs,
so Midhaul latency is the DetNet architecture, however for subnets with specific
protocols (e.g. CoAP) a gateway may be required.

6TiSCH devices dominating limitation of CoMP performance.
Generally, CoMP can discover their neighbors over the radio using a
mechanism such as beacons, but even though benefit from coordinated scheduling (either
distributed or centralized) of different cells if the neighbor information signaling delay
between eNBs is within 1-10ms. This delay requirement is available both rigid
and absolute because any uncertainty in delay will degrade the 6TiSCH interface data model, 6TiSCH does not
describe a protocol to proactively push the neighborhood information
to a PCE. We would like to see DetNet define such a protocol;
performance significantly.

Inter-site CoMP is one
possible design alternative of the key requirements for 5G and is that it could operate over CoAP,
alternatively it could be converted to/from CoAP by a gateway. We
would like to see such also a protocol carry multiple metrics,
near-term goal for example
similar to those used the current 4.5G network architecture.

6.1.3. Time Synchronization Constraints

Fronthaul time synchronization requirements are given by [TS25104],
[TS36104], [TS36211], and [TS36133]. These can be summarized for RPL operations [RFC6551]

5.3.2.2. 6TiSCH IP Interface

"6top" ([I-D.wang-6tisch-6top-sublayer]) the
current 3GPP LTE-based networks as:

Delay Accuracy:
+-8ns (i.e. +-1/32 Tc, where Tc is the UMTS Chip time of 1/3.84
MHz) resulting in a logical link control
sitting between round trip accuracy of +-16ns. The value is
this low to meet the IP layer and 3GPP Timing Alignment Error (TAE) measurement
requirements. Note: performance guarantees of low nanosecond
values such as these are considered to be below the TSCH MAC DetNet layer which provides
the link abstraction that -
it is required for IP operations. The 6top
data model and management interfaces are further discussed in
[I-D.ietf-6tisch-6top-interface] and [I-D.ietf-6tisch-coap].

An IP packet assumed that is sent along a 6TiSCH path uses the Differentiated
Services Per-Hop-Behavior Group called Deterministic Forwarding, as
described in [I-D.svshah-tsvwg-deterministic-forwarding].

5.3.3. 6TiSCH Security Considerations

On top underlying implementation, e.g. the
hardware, will provide sufficient support (e.g. buffering) to
enable this level of accuracy. These values are maintained in the classical requirements for protection
use case to give an indication of control
signaling, it the overall application.

Timing Alignment Error:
Timing Alignment Error (TAE) is problematic to Fronthaul networks
and must be noted that 6TiSCH networks operate on limited
resources that can minimized. If the transport network cannot guarantee
low enough TAE then additional buffering has to be depleted rapidly in a DoS attack on introduced at
the system,
for instance by placing a rogue device in edges of the network, or by
obtaining management control and setting up unexpected additional
paths.

5.4. Wireless Industrial Asks

6TiSCH depends on DetNet network to define:

o Configuration (state) and operations for deterministic paths

o End-to-end protocols for deterministic forwarding (tagging, IP)

o Protocol buffer out the jitter. Buffering is
not desirable as it reduces the total available delay budget.
Packet Delay Variation (PDV) requirements can be derived from TAE
for packet replication and elimination

6. Cellular Radio

6.1. Use Case Description based Fronthaul networks.

* For multiple input multiple output (MIMO) or TX diversity
transmissions, at each carrier frequency, TAE shall not exceed
65 ns (i.e. 1/4 Tc).

* For intra-band contiguous carrier aggregation, with or without
MIMO or TX diversity, TAE shall not exceed 130 ns (i.e. 1/2
Tc).

* For intra-band non-contiguous carrier aggregation, with or
without MIMO or TX diversity, TAE shall not exceed 260 ns (i.e.
one Tc).

* For inter-band carrier aggregation, with or without MIMO or TX
diversity, TAE shall not exceed 260 ns.

Transport link contribution to radio frequency error:
+-2 PPB. This use case describes value is considered to be "available" for the application
Fronthaul link out of deterministic networking
in the context of cellular telecom transport networks. Important
elements include time synchronization, clock distribution, and ways
of establishing time-sensitive streams total 50 PPB budget reserved for both Layer-2 and Layer-3
user plane traffic.

6.1.1. Network Architecture

Figure 10 illustrates a typical 3GPP-defined cellular network
architecture, which includes "Fronthaul" and "Midhaul" network
segments. The "Fronthaul" is the network connecting base stations
(baseband processing units) to the remote
radio heads (antennas).
The "Midhaul" is the network inter-connecting base stations (or small
cell sites).

In Figure 10 "eNB" ("E-UTRAN Node B") is interface. Note: the hardware reason that is
connected to the mobile phone network which communicates directly
with mobile handsets ([TS36300]).

Y (remote transport link
contributes to radio heads (antennas))
\
Y__ \.--. .--. +------+
\_( `. +---+ _(Back`. | 3GPP |
Y------( Front )----|eNB|----( Haul )----| core |
( ` .Haul ) +---+ ( ` . ) ) | netw |
/`--(___.-' \ `--(___.-' +------+
Y_/ / \.--. \
Y_/ _( Mid`. \
( Haul ) \
( ` . ) ) \
`--(___.-'\_____+---+ (small cell sites)
\ |SCe|__Y
+---+ +---+
Y__|eNB|__Y
+---+
Y_/ \_Y ("local" radios)

Figure 10: Generic 3GPP-based Cellular Network Architecture

6.1.2. Delay Constraints frequency error is as follows. The available processing time for current
way of doing Fronthaul networking overhead is
limited to the available time after the baseband processing of from the radio frame has completed. For example in Long Term Evolution (LTE)
radio, processing of a unit to remote radio head
directly. The remote radio frame head is allocated 3ms but typically the
processing uses most of it, allowing only essentially a small fraction to be used
by passive device
(without buffering etc.) The transport drives the Fronthaul network (e.g. up to 250us one-way delay, though antenna
directly by feeding it with samples and everything the
existing spec ([NGMN-fronth]) supports delay only up transport
adds will be introduced to 100us). This
ultimately determines radio as-is. So if the distance transport
causes additional frequency error that shows immediately on the remote
radio heads can as well. Note: performance guarantees of low nanosecond
values such as these are considered to be
located from below the base stations (e.g., 100us equals roughly 20 km of
optical fiber-based transport). Allocation options of DetNet layer -
it is assumed that the available
time budget between processing and transport underlying implementation, e.g. the
hardware, will provide sufficient support to enable this level of
performance. These values are under heavy
discussions maintained in the mobile industry.

For packet-based transport use case to give
an indication of the allocated transport overall application.

The above listed time (e.g. CPRI
would allow for 100us delay [CPRI]) is consumed by all nodes synchronization requirements are difficult to
meet with point-to-point connected networks, and more difficult when
the network includes multiple hops. It is expected that networks
must include buffering between at the remote radio head ends of the connections as imposed by
the jitter requirements, since trying to meet the jitter requirements
in every intermediate node is likely to be too costly. However,
every measure to reduce jitter and delay on the path makes it easier
to meet the baseband processing
unit, plus end-to-end requirements.

In order to meet the distance-incurred delay.

The baseband processing time timing requirements both senders and the available "delay budget" receivers
must remain time synchronized, demanding very accurate clock
distribution, for example support for IEEE 1588 transparent clocks or
boundary clocks in every intermediate node.

In cellular networks from the
fronthaul LTE radio era onward, phase
synchronization is likely to change needed in the forthcoming "5G" due addition to reduced
radio round trip times and other architectural frequency synchronization
([TS36300], [TS23401]).

6.1.4. Transport Loss Constraints

Fronthaul and service
requirements [NGMN].

[METIS] documents the fundamental challenges as well as overall
technical goals Midhaul networks assume almost error-free transport.
Errors can result in a reset of the future 5G radio interfaces, which can cause
reduced throughput or broken radio connectivity for mobile customers.

For packetized Fronthaul and wireless system as the
starting point. These future systems should support much higher data
volumes and rates and significantly lower end-to-end latency Midhaul connections packet loss may be
caused by BER, congestion, or network failure scenarios. Current
tools for 100x
more connected devices (at similar cost elminating packet loss for Fronthaul and energy consumption levels
as today's system).

For Midhaul connections, networks
have serious challenges, for example retransmitting lost packets and/
or using forward error correction (FEC) to circumvent bit errors is
practically impossible due to the additional delay constraints are driven by Inter-Site
radio functions like Coordinated Multipoint Processing (CoMP, see
[CoMP]). CoMP reception incurred. Using
redundant streams for better guarantees for delivery is also
practically impossible in many cases due to high bandwidth
requirements of Fronthaul and transmission Midhaul networks. Protection switching
is also a framework in which
multiple geographically distributed antenna nodes cooperate to
improve candidate but current technologies for the performance path switch are
too slow to avoid reset of mobile interfaces.

Fronthaul links are assumed to be symmetric, and all Fronthaul
streams (i.e. those carrying radio data) have equal priority and
cannot delay or pre-empt each other. This implies that the users served network
must guarantee that each time-sensitive flow meets their schedule.

6.1.5. Security Considerations

Establishing time-sensitive streams in the common cooperation
area. The design principal network entails reserving
networking resources for long periods of CoMP time. It is important that
these reservation requests be authenticated to extend prevent malicious
reservation attempts from hostile nodes (or accidental
misconfiguration). This is particularly important in the current single-
cell to multi-UE (User Equipment) transmission case where
the reservation requests span administrative domains. Furthermore,
the reservation information itself should be digitally signed to a multi-cell-to-
multi-UEs transmission by base station cooperation.

CoMP has delay-sensitive performance parameters, which are "midhaul
latency" and "CSI (Channel State Information) reporting and
accuracy". The essential feature of CoMP is signaling between eNBs,
so Midhaul latency is
reduce the dominating limitation risk of CoMP performance.
Generally, CoMP can benefit from coordinated scheduling (either
distributed a legitimate node pushing a stale or centralized) of different cells if the signaling delay
between eNBs is within 1-10ms. hostile
configuration into another networking node.

Note: This delay requirement is both rigid
and absolute because any uncertainty in delay will degrade considered important for the
performance significantly.

Inter-site CoMP is one security policy of the key requirements for 5G
network, but does not affect the core DetNet architecture and design.

6.2. Cellular Radio Networks Today

6.2.1. Fronthaul

Today's Fronthaul networks typically consist of:

o Dedicated point-to-point fiber connection is also a
near-term goal common

o Proprietary protocols and framings

o Custom equipment and no real networking

Current solutions for the current 4.5G network architecture.

6.1.3. Time Synchronization Constraints Fronthaul time synchronization requirements are given by [TS25104],
[TS36104], [TS36211], direct optical cables or
Wavelength-Division Multiplexing (WDM) connections.

6.2.2. Midhaul and [TS36133]. These can be summarized for Backhaul

Today's Midhaul and Backhaul networks typically consist of:

o Mostly normal IP networks, MPLS-TP, etc.

o Clock distribution and sync using 1588 and SyncE

Telecommunication networks in the
current 3GPP LTE-based Mid- and Backhaul are already
heading towards transport networks as:

Delay Accuracy:
+-8ns (i.e. +-1/32 Tc, where Tc is the UMTS Chip precise time of 1/3.84
MHz) resulting in a round trip accuracy of +-16ns. The value synchronization
support is
this low to meet the 3GPP Timing Alignment Error (TAE) measurement
requirements. Note: performance guarantees one of low nanosecond
values such as these are considered to be below the DetNet layer -
it is assumed that the underlying implementation, e.g. basic building blocks. While the
hardware, will provide sufficient support (e.g. buffering) transport
networks themselves have practically transitioned to
enable this level of accuracy. These values are maintained in the
use case all-IP packet-
based networks to give an indication of meet the overall application.

Timing Alignment Error:
Timing Alignment Error (TAE) is problematic to Fronthaul networks bandwidth and must be minimized. If the transport network cannot guarantee
low enough TAE then additional buffering cost requirements, highly
accurate clock distribution has to be introduced at become a challenge.

In the edges past, Mid- and Backhaul connections were typically based on
Time Division Multiplexing (TDM-based) and provided frequency
synchronization capabilities as a part of the network transport media.
Alternatively other technologies such as Global Positioning System
(GPS) or Synchronous Ethernet (SyncE) are used [SyncE].

Both Ethernet and IP/MPLS [RFC3031] (and PseudoWires (PWE) [RFC3985]
for legacy transport support) have become popular tools to buffer out the jitter. Buffering is build and
manage new all-IP Radio Access Networks (RANs)
[I-D.kh-spring-ip-ran-use-case]. Although various timing and
synchronization optimizations have already been proposed and
implemented including 1588 PTP enhancements
[I-D.ietf-tictoc-1588overmpls] and [I-D.ietf-mpls-residence-time],
these solution are not desirable as it reduces necessarily sufficient for the total available delay budget.
Packet Delay Variation (PDV) forthcoming RAN
architectures nor do they guarantee the more stringent time-
synchronization requirements can be derived from TAE such as [CPRI].

There are also existing solutions for packet based Fronthaul networks.

* For multiple input multiple output (MIMO) or TX diversity
transmissions, at each carrier frequency, TAE shall not exceed
65 ns (i.e. 1/4 Tc).

* For intra-band contiguous carrier aggregation, with or without
MIMO or TX diversity, TAE shall not exceed 130 ns (i.e. 1/2
Tc).

* For intra-band non-contiguous carrier aggregation, with or
without MIMO or TX diversity, TAE shall not exceed 260 ns (i.e.
one Tc).

* For inter-band carrier aggregation, with or without MIMO or TX
diversity, TAE shall not exceed 260 ns.

Transport link contribution to radio frequency error:
+-2 PPB. This value is considered to TDM over IP such as [RFC5087]
and [RFC4553], as well as TDM over Ethernet transports such as
[RFC5086].

6.3. Cellular Radio Networks Future

Future Cellular Radio Networks will be "available" for the
Fronthaul link out based on a mix of the total 50 PPB budget reserved for the
radio interface. Note: the reason that the different
xHaul networks (xHaul = front-, mid- and backhaul), and future
transport link
contributes networks should be able to radio frequency error is as follows. The current
way support all of doing Fronthaul them
simultaneously. It is from the radio unit to remote radio head
directly. The remote already envisioned today that:

o Not all "cellular radio head is essentially a passive device
(without buffering etc.) The transport drives the antenna
directly by feeding it network" traffic will be IP, for example
some will remain at Layer 2 (e.g. Ethernet based). DetNet
solutions must address all traffic types (Layer 2, Layer 3) with samples and everything
the same tools and allow their transport
adds simultaneously.

o All form of xHaul networks will be introduced need some form of DetNet
solutions. For example with the advent of 5G some Backhaul
traffic will also have DetNet requirements (e.g. traffic belonging
to radio as-is. So if time-critical 5G applications).

We would like to see the following in future Cellular Radio networks:

o Unified standards-based transport
causes additional frequency error protocols and standard
networking equipment that shows immediately on can make use of underlying deterministic
link-layer services

o Unified and standards-based network management systems and
protocols in all parts of the network (including Fronthaul)

New radio as well. Note: performance guarantees access network deployment models and architectures may
require time- sensitive networking services with strict requirements
on other parts of low nanosecond
values such as these are the network that previously were not considered to
be below the DetNet layer -
it is assumed that the underlying implementation, e.g. the
hardware, will provide sufficient packetized at all. Time and synchronization support to enable this level of
performance. These values are maintained already
topical for Backhaul and Midhaul packet networks [MEF] and are
becoming a real issue for Fronthaul networks also. Specifically in
Fronthaul networks the use case to give
an indication of the overall application.

The above listed time timing and synchronization requirements are difficult to
meet with point-to-point connected networks, and more difficult when
the network includes multiple hops. It is expected that networks
must include buffering at can be
extreme for packet based technologies, for example, on the ends order of the connections as imposed by
the jitter requirements, since trying
sub +-20 ns packet delay variation (PDV) and frequency accuracy of
+0.002 PPM [Fronthaul].

The actual transport protocols and/or solutions to meet the jitter requirements
in every intermediate node is establish required
transport "circuits" (pinned-down paths) for Fronthaul traffic are
still undefined. Those are likely to be too costly. However,
every measure to reduce jitter include (but are not limited
to) solutions directly over Ethernet, over IP, and delay on the path makes it easier
to meet using MPLS/
PseudoWire transport.

Even the end-to-end requirements.

In order to meet current time-sensitive networking features may not be
sufficient for Fronthaul traffic. Therefore, having specific
profiles that take the timing requirements both senders and receivers
must remain time synchronized, demanding very accurate clock
distribution, of Fronthaul into account is
desirable [IEEE8021CM].

Interesting and important work for example support time-sensitive networking has been
done for Ethernet [TSNTG], which specifies the use of IEEE 1588 transparent clocks time
precision protocol (PTP) [IEEE1588] in
every intermediate node.

In cellular networks from the LTE radio era onward, phase
synchronization is needed in addition to frequency synchronization
([TS36300], [TS23401]).

6.1.4. Transport Loss Constraints

Fronthaul context of IEEE 802.1D and Midhaul networks assume almost error-free transport.
Errors can result in
IEEE 802.1Q. [IEEE8021AS] specifies a reset of the radio interfaces, which can cause
reduced throughput or broken radio connectivity for mobile customers.

For packetized Fronthaul Layer 2 time synchronizing
service, and Midhaul connections packet loss may be
caused by BER, congestion, or network failure scenarios. Current
tools for elminating packet loss other specifications such as IEEE 1722 [IEEE1722]
specify Ethernet-based Layer-2 transport for Fronthaul and Midhaul time-sensitive streams.

New promising work seeks to enable the transport of time-sensitive
fronthaul streams in Ethernet bridged networks
have serious challenges, for example retransmitting lost packets and/
or using forward error correction (FEC) [IEEE8021CM].
Analogous to circumvent bit errors IEEE 1722 there is
practically impossible due an ongoing standardization effort to
define the additional delay incurred. Using
redundant streams Layer-2 transport encapsulation format for better guarantees transporting
radio over Ethernet (RoE) in the IEEE 1904.3 Task Force [IEEE19043].

All-IP RANs and xHhaul networks would benefit from time
synchronization and time-sensitive transport services. Although
Ethernet appears to be the unifying technology for delivery the transport,
there is also
practically impossible in many cases due still a disconnect providing Layer 3 services. The protocol
stack typically has a number of layers below the Ethernet Layer 2
that shows up to high bandwidth
requirements the Layer 3 IP transport. It is not uncommon that
on top of Fronthaul and Midhaul networks. Protection switching the lowest layer (optical) transport there is also a candidate but current technologies for the path switch are
too slow to avoid reset first
layer of mobile interfaces.

Fronthaul links Ethernet followed one or more layers of MPLS, PseudoWires
and/or other tunneling protocols finally carrying the Ethernet layer
visible to the user plane IP traffic.

While there are assumed existing technologies to be symmetric, and all Fronthaul
streams (i.e. those carrying radio data) have equal priority and
cannot delay or pre-empt each other. This implies that establish circuits through
the network
must guarantee that each time-sensitive flow meets their schedule.

6.1.5. Security Considerations

Establishing time-sensitive streams routed and switched networks (especially in the network entails reserving
networking resources for long periods of time. It MPLS/PWE space),
there is important that
these reservation requests be authenticated still no way to prevent malicious
reservation attempts from hostile nodes (or accidental
misconfiguration). This is particularly important signal the time synchronization and time-
sensitive stream requirements/reservations for Layer-3 flows in a way
that addresses the case where entire transport stack, including the reservation requests span administrative domains. Ethernet
layers that need to be configured.

Furthermore,
the reservation information itself should not all "user plane" traffic will be digitally signed to
reduce IP. Therefore, the risk of a legitimate node pushing a stale or hostile
configuration into another networking node.

Note: This
same solution also must address the use cases where the user plane
traffic is considered important a different layer, for example Ethernet frames.

There is existing work describing the security policy of the
network, but does not affect problem statement
[I-D.finn-detnet-problem-statement] and the core DetNet architecture and design.

6.2.
[I-D.finn-detnet-architecture] for deterministic networking (DetNet)
that targets solutions for time-sensitive (IP/transport) streams with
deterministic properties over Ethernet-based switched networks.

6.4. Cellular Radio Networks Today

6.2.1. Fronthaul

Today's Fronthaul networks typically consist of:

o Dedicated point-to-point fiber connection is common Asks

A standard for data plane transport specification which is:

o Proprietary protocols Unified among all xHauls (meaning that different flows with
diverse DetNet requirements can coexist in the same network and framings
traverse the same nodes without interfering with each other)

o Custom equipment and no real networking

Current solutions Deployed in a highly deterministic network environment

A standard for Fronthaul are direct optical cables or
Wavelength-Division Multiplexing (WDM) connections.

6.2.2. Midhaul and Backhaul

Today's Midhaul and Backhaul networks typically consist of:

o Mostly normal IP networks, MPLS-TP, etc. data flow information models that are:

o Clock distribution and sync using 1588 and SyncE

Telecommunication networks in Aware of the Mid- and Backhaul are already
heading towards transport networks where precise time synchronization
support is one sensitivity and constraints of the basic building blocks. While target
networking environment

o Aware of underlying deterministic networking services (e.g., on
the transport
networks themselves have practically transitioned to all-IP packet-
based networks Ethernet layer)

7. Industrial M2M

7.1. Use Case Description

Industrial Automation in general refers to meet the bandwidth and cost requirements, highly
accurate clock distribution has become a challenge.

In the past, Mid- and Backhaul connections were typically based on
Time Division Multiplexing (TDM-based) automation of
manufacturing, quality control and provided frequency
synchronization capabilities as material processing. In this
"machine to machine" (M2M) use case we consider machine units in a part of the transport media.
Alternatively other technologies such as Global Positioning System
(GPS)
plant floor which periodically exchange data with upstream or Synchronous Ethernet (SyncE)
downstream machine modules and/or a supervisory controller within a
local area network.

The actors of M2M communication are used [SyncE].

Both Ethernet and IP/MPLS [RFC3031] (and PseudoWires (PWE) [RFC3985]
for legacy transport support) have become popular tools to build and
manage new all-IP Radio Access Networks (RANs)
[I-D.kh-spring-ip-ran-use-case]. Although various timing and
synchronization optimizations have already been proposed Programmable Logic Controllers
(PLCs). Communication between PLCs and
implemented including 1588 PTP enhancements
[I-D.ietf-tictoc-1588overmpls] between PLCs and [I-D.ietf-mpls-residence-time],
these solution are not necessarily sufficient for the forthcoming RAN
architectures nor do they guarantee the more stringent time-
synchronization requirements such as [CPRI].

There are also existing solutions for TDM over IP such as [RFC5087]
and [RFC4553], as well as TDM over Ethernet transports such as
[RFC5086].

6.3. Cellular Radio Networks Future

Future Cellular Radio Networks will be based
supervisory PLC (S-PLC) is achieved via critical control/data streams
Figure 11.

S (Sensor)
\ +-----+
PLC__ \.--. .--. ---| MES |
\_( `. _( `./ +-----+
A------( Local )-------------( L2 )
( Net ) ( Net ) +-------+
/`--(___.-' `--(___.-' ----| S-PLC |
S_/ / PLC .--. / +-------+
A_/ \_( `.
(Actuator) ( Local )
( Net )
/`--(___.-'\
/ \ A
S A

Figure 11: Current Generic Industrial M2M Network Architecture

This use case focuses on a mix PLC-related communications; communication to
Manufacturing-Execution-Systems (MESs) are not addressed.

This use case covers only critical control/data streams; non-critical
traffic between industrial automation applications (such as
communication of different
xHaul networks (xHaul = front-, mid- and backhaul), state, configuration, set-up, and future
transport networks should be able database
communication) are adequately served by currently available
prioritizing techniques. Such traffic can use up to support all 80% of them
simultaneously. It the total
bandwidth required. There is already envisioned today that:

o Not all "cellular radio network" also a subset of non-time-critical
traffic will be IP, for example
some will remain at Layer 2 (e.g. Ethernet based). DetNet
solutions that must address all traffic types (Layer 2, Layer 3) with be reliable even though it is not time sensitive.

In this use case the same tools and allow their transport simultaneously.

o All form of xHaul networks will primary need some form of DetNet
solutions. For example with the advent of 5G some Backhaul
traffic will also have DetNet requirements (e.g. traffic belonging
to time-critical 5G applications).

We would like to see the following in future Cellular Radio networks:

o Unified standards-based transport protocols and standard for deterministic networking equipment that can make use is to
provide end-to-end delivery of underlying deterministic
link-layer services

o Unified and standards-based network management systems and
protocols M2M messages within specific timing
constraints, for example in all parts closed loop automation control. Today
this level of the network (including Fronthaul)

New radio access network deployment models and architectures may
require time- sensitive determinism is provided by proprietary networking
technologies. In addition, standard networking services with strict requirements
on other parts of technologies are used
to connect the local network to remote industrial automation sites,
e.g. over an enterprise or metro network which also carries other
types of traffic. Therefore, flows that previously were not considered should be forwarded with
deterministic guarantees need to be packetized at all. Time and synchronization support are already
topical for Backhaul and Midhaul packet networks [MEF] and are
becoming a real issue for Fronthaul networks also. Specifically sustained regardless of the
amount of other flows in
Fronthaul those networks.

7.2. Industrial M2M Communication Today

Today, proprietary networks fulfill the needed timing and synchronization requirements can be
extreme for packet based technologies,
availability for example, on the order of
sub +-20 ns packet delay variation (PDV) and frequency accuracy of
+0.002 PPM [Fronthaul]. M2M networks.

The actual transport protocols and/or solutions to establish required
transport "circuits" (pinned-down paths) for Fronthaul traffic are
still undefined. Those network topologies used today by industrial automation are likely
similar to include (but those used by telecom networks: Daisy Chain, Ring, Hub and
Spoke, and Comb (a subset of Daisy Chain).

PLC-related control/data streams are not limited
to) solutions directly over Ethernet, over IP, transmitted periodically and using MPLS/
PseudoWire transport.
carry either a pre-configured payload or a payload configured during
runtime.

Some industrial applications require time synchronization at the end
nodes. For such time-coordinated PLCs, accuracy of 1 microsecond is
required. Even in the current time-sensitive networking features case of "non-time-coordinated" PLCs time sync
may not be
sufficient for Fronthaul traffic. Therefore, having specific
profiles needed e.g. for timestamping of sensor data.

Industrial network scenarios require advanced security solutions.
Many of the current industrial production networks are physically
separated. Preventing critical flows from be leaked outside a domain
is handled today by filtering policies that take are typically enforced in
firewalls.

7.2.1. Transport Parameters

The Cycle Time defines the requirements frequency of Fronthaul into account message(s) between industrial
actors. The Cycle Time is
desirable [IEEE8021CM].

Interesting and important work application dependent, in the range of 1ms
- 100ms for time-sensitive networking has been
done critical control/data streams.

Because industrial applications assume deterministic transport for Ethernet [TSNTG], which specifies
critical Control-Data-Stream parameters (instead of defining latency
and delay variation parameters) it is sufficient to fulfill the use upper
bound of IEEE 1588 latency (maximum latency). The underlying networking
infrastructure must ensure a maximum end-to-end delivery time
precision protocol (PTP) [IEEE1588] of
messages in the context range of IEEE 802.1D and
IEEE 802.1Q. [IEEE8021AS] specifies a Layer 2 time synchronizing
service, and other specifications such as IEEE 1722 [IEEE1722]
specify Ethernet-based Layer-2 transport for time-sensitive streams.

New promising work seeks 100 microseconds to enable 50 milliseconds
depending on the transport control loop application.

The bandwidth requirements of time-sensitive
fronthaul control/data streams in Ethernet bridged networks [IEEE8021CM].
Analogous to IEEE 1722 there is an ongoing standardization effort to
define are usually
calculated directly from the Layer-2 transport encapsulation format for transporting
radio over Ethernet (RoE) bytes-per-cycle parameter of the control
loop. For PLC-to-PLC communication one can expect 2 - 32 streams
with packet size in the IEEE 1904.3 Task Force [IEEE19043].

All-IP RANs and xHhaul networks would benefit from time
synchronization and time-sensitive transport services. Although
Ethernet appears range of 100 - 700 bytes. For S-PLC to be the unifying technology for PLCs
the transport,
there is still a disconnect providing Layer 3 services. The protocol
stack typically has a number of layers below the Ethernet Layer 2
that shows streams is higher - up to the Layer 3 IP transport. It is not uncommon that
on top 256 streams. Usually no more
than 20% of the lowest layer (optical) transport there available bandwidth is the first
layer used for critical control/data
streams. In today's networks 1Gbps links are commonly used.

Most PLC control loops are rather tolerant of Ethernet followed one or packet loss, however
critical control/data streams accept no more layers of MPLS, PseudoWires
and/or other tunneling protocols finally carrying than 1 packet loss per
consecutive communication cycle (i.e. if a packet gets lost in cycle
"n", then the Ethernet layer
visible to next cycle ("n+1") must be lossless). After two or
more consecutive packet losses the user plane IP traffic.

While there are existing technologies network may be considered to establish circuits through be
"down" by the routed and switched networks (especially in MPLS/PWE space),
there is still no way to signal Application.

As network downtime may impact the time synchronization and time-
sensitive stream requirements/reservations for Layer-3 flows in a way
that addresses whole production system the entire transport stack, including
required network availability is rather high (99,999%).

Based on the Ethernet
layers above parameters we expect that need to be configured.

Furthermore, not all "user plane" traffic some form of redundancy
will be IP. Therefore, the
same required for M2M communications, however any individual
solution also must address the use cases where depends on several parameters including cycle time, delivery
time, etc.

7.2.2. Stream Creation and Destruction

In an industrial environment, critical control/data streams are
created rather infrequently, on the user plane
traffic order of ~10 times per day / week
/ month. Most of these critical control/data streams get created at
machine startup, however flexibility is a different layer, also needed during runtime,
for example Ethernet frames.

There is existing work describing the problem statement
[I-D.finn-detnet-problem-statement] and when adding or removing a machine. Going forward as
production systems become more flexible, we expect a significant
increase in the architecture
[I-D.finn-detnet-architecture] for deterministic networking (DetNet)
that targets solutions for time-sensitive (IP/transport) rate at which streams are created, changed and
destroyed.

7.3. Industrial M2M Future

We would like to see a converged IP-standards-based network with
deterministic properties over Ethernet-based switched networks.

6.4. Cellular Radio Networks Asks

A standard for data plane transport specification which is:

o Unified among all xHauls (meaning that different flows with
diverse DetNet requirements can coexist in satisfy the same network timing, security and
traverse the same nodes without interfering with each other)

o Deployed in
reliability constraints described above. Today's proprietary
networks could then be interfaced to such a highly deterministic network environment

A standard for data flow information models that are:

o Aware of the time sensitivity and constraints of the target
networking environment

o Aware of underlying deterministic networking services (e.g., on
the Ethernet layer)

7. Industrial M2M

7.1. Use Case Description

Industrial Automation via gateways or,
in general refers to automation the case of
manufacturing, quality control and material processing. In this
"machine new installations, devices could be connected directly
to machine" (M2M) the converged network.

For this use case we consider machine units in a
plant floor which periodically exchange data with upstream or
downstream machine modules and/or a supervisory controller within a
local area network.

The actors expect time synchronization accuracy on the
order of 1us.

7.4. Industrial M2M communication are Programmable Logic Controllers
(PLCs). Communication between PLCs and between PLCs Asks

o Converged IP-based network

o Deterministic behavior (bounded latency and the
supervisory PLC (S-PLC) is achieved via critical control/data streams
Figure 11.

Figure 11: Current Generic Industrial M2M Network Architecture

o High availability (presumably through redundancy) (99.999 %)

o Low message delivery time (100us - 50ms)

o Low packet loss (burstless, 0.1-1 %)

o Security (e.g. prevent critical flows from being leaked between
physically separated networks)

8. Use Case Common Themes

This use case focuses section summarizes the expected properties of a DetNet network,
based on PLC-related communications; communication to
Manufacturing-Execution-Systems (MESs) are not addressed.

This the use case covers only critical control/data streams; non-critical
traffic between industrial automation applications (such cases as
communication described in this draft.

8.1. Unified, standards-based network

8.1.1. Extensions to Ethernet

A DetNet network is not "a new kind of state, configuration, set-up, network" - it based on
extensions to existing Ethernet standards, including elements of IEEE
802.1 AVB/TSN and related standards. Presumably it will be possible
to run DetNet over other underlying transports besides Ethernet, but
Ethernet is explicitly supported.

8.1.2. Centrally Administered

In general a DetNet network is not expected to be "plug and database
communication) are adequately served by currently available
prioritizing techniques. play" -
it is expected that there is some centralized network configuration
and control system. Such traffic can use up a system may be in a single central
location, or it maybe distributed across multiple control entities
that function together as a unified control system for the network.
However, the ability to 80% "hot swap" components (e.g. due to
malfunction) is similar enough to "plug and play" that this kind of
behavior may be expected in DetNet networks, depending on the total
bandwidth required. There
implementation.

8.1.3. Standardized Data Flow Information Models

Data Flow Information Models to be used with DetNet networks are to
be specified by DetNet.

8.1.4. L2 and L3 Integration

A DetNet network is also a subset intended to integrate between Layer 2 (bridged)
network(s) (e.g. AVB/TSN LAN) and Layer 3 (routed) network(s) (e.g.
using IP-based protocols). One example of non-time-critical
traffic that must be reliable even though it this is "making AVB/TSN-
type deterministic performance available from Layer 3 applications,
e.g. using RTP". Another example is "connecting two AVB/TSN LANs
("islands") together through a standard router".

8.1.5. Guaranteed End-to-End Delivery

Packets sent over DetNet are guaranteed not time sensitive.

In this use case to be dropped by the primary need
network due to congestion. (Packets may however be dropped for
intended reasons, e.g. per security measures).

8.1.6. Replacement for Multiple Proprietary Deterministic Networks

There are many proprietary non-interoperable deterministic networking Ethernet-
based networks currently available; DetNet is intended to provide end-to-end delivery an
open-standards-based alternative to such networks.

8.1.7. Mix of M2M messages within specific timing
constraints, Deterministic and Best-Effort Traffic

DetNet is intended to support coexistance of time-sensitive
operational (OT) traffic and information (IT) traffic on the same
("unified") network.

8.1.8. Unused Reserved BW to be Available to Best Effort Traffic

If bandwidth reservations are made for example in closed loop automation control. Today
this level of determinism a stream but the associated
bandwidth is provided by proprietary networking
technologies. In addition, standard networking technologies are not used
to connect at any point in time, that bandwidth is made
available on the local network to remote industrial automation sites,
e.g. over an enterprise or metro network which also carries other
types of for best-effort traffic. Therefore, flows that should be forwarded with
deterministic guarantees need to be sustained regardless of If the
amount owner of other flows in those networks.

7.2. Industrial M2M Communication Today

Today, proprietary networks fulfill
the needed timing and
availability reserved stream then starts transmitting again, the bandwidth is
no longer available for M2M networks. best-effort traffic, on a moment-to-moment
basis. Note that such "temporarily available" bandwidth is not
available for time-sensitive traffic, which must have its own
reservation.

8.1.9. Lower Cost, Multi-Vendor Solutions

The DetNet network topologies used today by industrial automation specifications are
similar intended to those used by telecom networks: Daisy Chain, Ring, Hub and
Spoke, enable an ecosystem
in which multiple vendors can create interoperable products, thus
promoting device diversity and Comb (a subset potentially higher numbers of Daisy Chain).

PLC-related control/data streams are transmitted periodically each
device manufactured, promoting cost reduction and
carry either a pre-configured payload or a payload configured during
runtime.

Some industrial applications require time synchronization at the end
nodes. For such time-coordinated PLCs, accuracy of 1 microsecond cost competition
among vendors. The intent is
required. Even in the case of "non-time-coordinated" PLCs time sync
may that DetNet networks should be needed e.g. for timestamping of sensor data.

Industrial network scenarios require advanced security solutions.
Many able to
be created at lower cost and with greater diversity of the current industrial production available
devices than existing proprietary networks.

8.2. Scalable Size

DetNet networks are physically
separated. Preventing critical flows range in size from be leaked outside very small, e.g. inside a domain
is handled today by filtering policies single
industrial machine, to very large, for example a Utility Grid network
spanning a whole country, and involving many "hops" over various
kinds of links for example radio repeaters, microwave linkes, fiber
optic links, etc.. However recall that are typically enforced in
firewalls.

7.2.1. Transport Parameters

The Cycle Time defines the frequency scope of message(s) between industrial
actors. The Cycle Time DetNet is application dependent, in
confined to networks that are centrally administered, and explicitly
excludes unbounded decentralized networks such as the range of 1ms
- 100ms for critical control/data streams.

Because industrial applications assume deterministic transport for
critical Control-Data-Stream parameters (instead of defining latency Internet.

8.3. Scalable Timing Parameters and delay variation parameters) it Accuracy

8.3.1. Bounded Latency

The DetNet Data Flow Information Model is sufficient expected to fulfill provide means
to configure the upper
bound of network that include parameters for querying network
path latency, requesting bounded latency (maximum latency). The underlying networking
infrastructure must ensure for a given stream,
requesting worst case maximum end-to-end delivery time of
messages in the range of 100 microseconds to 50 milliseconds
depending on the control loop application.

The bandwidth requirements of control/data streams are usually
calculated directly from the bytes-per-cycle parameter of the control
loop. For PLC-to-PLC communication one can expect 2 - 32 streams
with packet size in the range of 100 - 700 bytes. For S-PLC to PLCs
the number of streams is higher - up to 256 streams. Usually no more
than 20% of available bandwidth is used and/or minimum latency for critical control/data
streams. In today's networks 1Gbps links are commonly used.

Most PLC control loops are rather tolerant of packet loss, however
critical control/data streams accept no more than 1 packet loss per
consecutive communication cycle (i.e. if a packet gets lost in cycle
"n", then the next cycle ("n+1") must be lossless). After two given path
or
more consecutive packet losses stream, and so on. It is an expected case that the network may
not be considered able to be
"down" by provide a given requested service level, and if so the Application.

As
network downtime may impact the whole production control system should reply that the
required network availability requested services is rather high (99,999%).

Based on
not available (as opposed to accepting the above parameters we expect that some form of redundancy
will be required for M2M communications, parameter but then not
delivering the desired behavior).

8.3.2. Low Latency

Applications may require "extremely low latency" however any individual
solution depends on several parameters including cycle time, delivery
time, etc.

7.2.2. Stream Creation and Destruction

In an industrial environment, critical control/data streams are
created rather infrequently, depending on
the order of ~10 times per day / week
/ month. Most of application these critical control/data streams get created at
machine startup, however flexibility is also needed during runtime, may mean very different latency values; for
example when adding or removing "low latency" across a machine. Going forward as
production systems become more flexible, we expect Utility grid network is on a significant
increase different
time scale than "low latency" in a motor control loop in a small
machine. The intent is that the mechanisms for specifying desired
latency include wide ranges, and that architecturally there is
nothing to prevent arbirtrarily low latencies from being implemented
in the rate at which streams are created, changed and
destroyed.

7.3. Industrial M2M Future

We a given network.

8.3.3. Symmetrical Path Delays

Some applications would like to see a converged IP-standards-based network with
deterministic properties specify that can satisfy the timing, security and
reliability constraints described above. Today's proprietary
networks could then transit delay time
values be interfaced equal for both the transmit and return paths.

8.4. High Reliability and Availability

Reliablity is of critical importance to such a network via gateways or, many DetNet applications, in the case
which consequences of new installations, devices could failure can be connected directly extraordinarily high in terms of
cost and even human life. DetNet based systems are expected to be
implemented with essentially arbitrarily high availability (for
example 99.9999% up time, or even 12 nines). The intent is that the converged network.

For this use case we expect time synchronization accuracy on
DetNet designs should not make any assumptions about the
order level of 1us.

7.4. Industrial M2M Asks

o Converged IP-based network

o Deterministic behavior (bounded latency
reliability and jitter )

o High availability (presumably through redundancy) (99.999 %)

o Low message delivery time (100us - 50ms)

o Low packet loss (burstless, 0.1-1 %)

o that may be required of a given system,
and should define parameters for communicating these kinds of metrics
within the network.

A strategy used by DetNet for providing such extraordinarily high
levels of reliability is to provide redundant paths that can be
seamlessly switched between, while maintaining the required
performance of that system.

8.5. Security (e.g. prevent

Security is of critical flows from being leaked between
physically separated networks)

8. Use Case Common Elements

Looking at importance to many DetNet applications. A
DetNet network must be able to be made secure against devices
failures, attackers, misbehaving devices, and so on. In a DetNet
network the use cases collectively, data traffic is expected to be be time-sensitive, thus in
addition to arriving with the following common desires
for data content as intended, the DetNet-based networks of data must
also arrive at the future emerge:

o Open standards-based network (replace various proprietary
networks, reduce cost, create multi-vendor market)

o Centrally administered (though such administration expected time. This may be
distributed for scale and resiliency)

o Integrates L2 (bridged) present "new" security
challenges to implementers, and L3 (routed) environments (independent
of the Link layer, e.g. can must be used with Ethernet, 6TiSCH, etc.)

o Carries both deterministic addressed accordingly. There
are other security implications, including (but not limited to) the
change in attack surface presented by packet replication and best-effort traffic (guaranteed
end-to-end delivery of deterministic flows, deterministic
elimination.

8.6. Deterministic Flows

Reserved bandwidth data flows must be isolated from each other and
from best-effort traffic congestion,
unused deterministic BW available to best-effort traffic)

o Ability to add or remove systems from traffic, so that even if the network is saturated
with minimal,
bounded service interruption (applications include replacement of
failed devices as well as plug and play)

o Uses standardized data flow information models capable of
expressing deterministic properties (models express device
capabilities, flow properties. Protocols for pushing models from
controller to devices, devices to controller)

o Scalable size (long distances (many km) and short distances
(within a single machine), many hops (radio repeaters, microwave
links, fiber links...) and short hops (single machine))

o Scalable timing parameters and accuracy (bounded latency,
guaranteed worst case maximum, minimum. Low latency, e.g. control
loops may be less than 1ms, but larger for wide area networks)

o High availability (99.9999 percent up time requested, but may be
up to twelve 9s)

o Reliability, redundancy (lives at stake)

o Security (from failures, attackers, misbehaving devices -
sensitive to both packet content and arrival time) best-effort (and/or reserved bandwidth) traffic, the configured
flows are not adversely affected.

9. Use Cases Explicitly Out of Scope for DetNet

This section contains use case text that has been determined to be
outside of the scope of the present DetNet work.

9.1. DetNet Scope Limitations

The scope of DetNet is deliberately limited to specific use cases
that are consistent with the WG charter, subject to the
interpretation of the WG. At the time the DetNet Use Cases were
solicited and provided by the authors the scope of DetNet was not
clearly defined, and as that clarity has emerged, certain of the use
cases have been determined to be outside the scope of the present
DetNet work. Such text has been moved into this section to clarify
that these use cases will not be supported by the DetNet work.

The text in this section was moved here based on the following
"exclusion" principles. Or, as an alternative to moving all such
text to this section, some draft text has been modified in situ to
reflect these same principles.

The following principles have been established to clarify the scope
of the present DetNet work.

o The scope of network addressed by DetNet is limited to networks
that can be centrally controlled, i.e. an "enterprise" aka
"corporate" network. This explicitly excludes "the open
Internet".

o Maintaining synchronized time across a DetNet network is crucial
to its operation, however DetNet assumes that time is to be
maintained using other means, for example (but not limited to)
Precision Time Protocol ([IEEE1588]). A use case may state the
accuracy and reliability that it expects from the DetNet network
as part of a whole system, however it is understood that such
timing properties are not guaranteed by DetNet itself. It is
currently an open question as to whether DetNet protocols will
include a way for an application to communicate such timing
expectations to the network, and if so whether they would be
expected to materially affect the performance they would receive
from the network as a result.

9.2. Internet-based Applications

9.2.1. Use Case Description

There are many applications that communicate across the open Internet
that could benefit from guaranteed delivery and bounded latency. The
following are some representative examples.

9.2.1.1. Media Content Delivery

Media content delivery continues to be an important use of the
Internet, yet users often experience poor quality audio and video due
to the delay and jitter inherent in today's Internet.

9.2.1.2. Online Gaming

Online gaming is a significant part of the gaming market, however
latency can degrade the end user experience. For example "First
Person Shooter" (FPS) games are highly delay-sensitive.

9.2.1.3. Virtual Reality

Virtual reality (VR) has many commercial applications including real
estate presentations, remote medical procedures, and so on. Low
latency is critical to interacting with the virtual world because
perceptual delays can cause motion sickness.

9.2.2. Internet-Based Applications Today

Internet service today is by definition "best effort", with no
guarantees on delivery or bandwidth.

9.2.3. Internet-Based Applications Future

We imagine an Internet from which we will be able to play a video
without glitches and play games without lag.

For online gaming, the maximum round-trip delay can be 100ms and
stricter for FPS gaming which can be 10-50ms. Transport delay is the
dominate part with a 5-20ms budget.

For VR, 1-10ms maximum delay is needed and total network budget is
1-5ms if doing remote VR.

Flow identification can be used for gaming and VR, i.e. it can
recognize a critical flow and provide appropriate latency bounds.

9.2.4. Internet-Based Applications Asks

o Unified control and management protocols to handle time-critical
data flow

o Application-aware flow filtering mechanism to recognize the timing
critical flow without doing 5-tuple matching

o Unified control plane to provide low latency service on Layer-3
without changing the data plane

o OAM system and protocols which can help to provide E2E-delay
sensitive service provisioning

9.3. Pro Audio and Video - Digital Rights Management (DRM)

This section was moved here because this is considered a Link layer
topic, not direct responsibility of DetNet.

Digital Rights Management (DRM) is very important to the audio and
video industries. Any time protected content is introduced into a
network there are DRM concerns that must be maintained (see
[CONTENT_PROTECTION]). Many aspects of DRM are outside the scope of
network technology, however there are cases when a secure link
supporting authentication and encryption is required by content
owners to carry their audio or video content when it is outside their
own secure environment (for example see [DCI]).

As an example, two techniques are Digital Transmission Content
Protection (DTCP) and High-Bandwidth Digital Content Protection
(HDCP). HDCP content is not approved for retransmission within any
other type of DRM, while DTCP may be retransmitted under HDCP.
Therefore if the source of a stream is outside of the network and it
uses HDCP protection it is only allowed to be placed on the network
with that same HDCP protection.

9.4. Pro Audio and Video - Link Aggregation

Note: The term "Link Aggregation" is used here as defined by the text
in the following paragraph, i.e. not following a more common Network
Industry definition. Current WG consensus is that this item won't be
directly supported by the DetNet architecture, for example because it
implies guarantee of in-order delivery of packets which conflicts
with the core goal of achieving the lowest possible latency.

For transmitting streams that require more bandwidth than a single
link in the target network can support, link aggregation is a
technique for combining (aggregating) the bandwidth available on
multiple physical links to create a single logical link of the
required bandwidth. However, if aggregation is to be used, the
network controller (or equivalent) must be able to determine the
maximum latency of any path through the aggregate link.

10. Acknowledgments

10.1. Pro Audio

This section was derived from draft-gunther-detnet-proaudio-req-01.

The editors would like to acknowledge the help of the following
individuals and the companies they represent:

Jeff Koftinoff, Meyer Sound

Jouni Korhonen, Associate Technical Director, Broadcom

Pascal Thubert, CTAO, Cisco

Kieran Tyrrell, Sienda New Media Technologies GmbH

10.2. Utility Telecom

This section was derived from draft-wetterwald-detnet-utilities-reqs-
02.

Faramarz Maghsoodlou, Ph. D. IoT Connected Industries and Energy
Practice Cisco

Pascal Thubert, CTAO Cisco

10.3. Building Automation Systems

This section was derived from draft-bas-usecase-detnet-00.

10.4. Wireless for Industrial

This section was derived from draft-thubert-6tisch-4detnet-01.

This specification derives from the 6TiSCH architecture, which is the
result of multiple interactions, in particular during the 6TiSCH
(bi)Weekly Interim call, relayed through the 6TiSCH mailing list at
the IETF.

The authors wish to thank: Kris Pister, Thomas Watteyne, Xavier
Vilajosana, Qin Wang, Tom Phinney, Robert Assimiti, Michael
Richardson, Zhuo Chen, Malisa Vucinic, Alfredo Grieco, Martin Turon,
Dominique Barthel, Elvis Vogli, Guillaume Gaillard, Herman Storey,
Maria Rita Palattella, Nicola Accettura, Patrick Wetterwald, Pouria
Zand, Raghuram Sudhaakar, and Shitanshu Shah for their participation
and various contributions.

10.5. Cellular Radio

This section was derived from draft-korhonen-detnet-telreq-00.

10.6. Industrial M2M

The authors would like to thank Feng Chen and Marcel Kiessling for
their comments and suggestions.

10.7. Internet Applications and CoMP

This section was derived from draft-zha-detnet-use-case-00.

This document has benefited from reviews, suggestions, comments and
proposed text provided by the following members, listed in
alphabetical order: Jing Huang, Junru Lin, Lehong Niu and Oilver
Huang.

10.8. Electrical Utilities

The wind power generation use case has been extracted from the study
of Wind Farms conducted within the 5GPPP Virtuwind Project. The
project is funded by the European Union's Horizon 2020 research and
innovation programme under grant agreement No 671648 (VirtuWind).

11. Informative References

[ACE] IETF, "Authentication and Authorization for Constrained
Environments", <https://datatracker.ietf.org/doc/charter-
ietf-ace/>.

[Ahm14] Ahmed, M. and R. Kim, "Communication network architectures
for smart-wind power farms.", Energies, p. 3900-3921. ,
June 2014.

[bacnetip]
ASHRAE, "Annex J to ANSI/ASHRAE 135-1995 - BACnet/IP",
January 1999.

[CCAMP] IETF, "Common Control and Measurement Plane",
<https://datatracker.ietf.org/doc/charter-ietf-ccamp/>.

[CoMP] NGMN Alliance, "RAN EVOLUTION PROJECT COMP EVALUATION AND
ENHANCEMENT", NGMN Alliance NGMN_RANEV_D3_CoMP_Evaluation_
and_Enhancement_v2.0, March 2015,
<https://www.ngmn.org/uploads/media/
NGMN_RANEV_D3_CoMP_Evaluation_and_Enhancement_v2.0.pdf>.

[CONTENT_PROTECTION]
Olsen, D., "1722a Content Protection", 2012,
<http://grouper.ieee.org/groups/1722/contributions/2012/
avtp_dolsen_1722a_content_protection.pdf>.

[CPRI] CPRI Cooperation, "Common Public Radio Interface (CPRI);
Interface Specification", CPRI Specification V6.1, July
2014, <http://www.cpri.info/downloads/
CPRI_v_6_1_2014-07-01.pdf>.

[CPRI-transp]
CPRI TWG, "CPRI requirements for Ethernet Fronthaul",
November 2015,
<http://www.ieee802.org/1/files/public/docs2015/
cm-CPRI-requirements-1115-v01.pdf>.

[DCI] Digital Cinema Initiatives, LLC, "DCI Specification,
Version 1.2", 2012, <http://www.dcimovies.com/>.

[DICE] IETF, "DTLS In Constrained Environments",
<https://datatracker.ietf.org/doc/charter-ietf-dice/>.

[EA12] Evans, P. and M. Annunziata, "Industrial Internet: Pushing
the Boundaries of Minds and Machines", November 2012.

[ESPN_DC2]
Daley, D., "ESPN's DC2 Scales AVB Large", 2014,
<http://sportsvideo.org/main/blog/2014/06/
espns-dc2-scales-avb-large>.

[flnet] Japan Electrical Manufacturers Association, "JEMA 1479 -
English Edition", September 2012.

[Fronthaul]
Chen, D. and T. Mustala, "Ethernet Fronthaul
Considerations", IEEE 1904.3, February 2015,
<http://www.ieee1904.org/3/meeting_archive/2015/02/
tf3_1502_che n_1a.pdf>.

[HART] www.hartcomm.org, "Highway Addressable remote Transducer,
a group of specifications for industrial process and
control devices administered by the HART Foundation".

[I-D.finn-detnet-architecture]
Finn, N. and P. Thubert, "Deterministic Networking
Architecture", draft-finn-detnet-architecture-08 (work in
progress), August 2016.

[I-D.finn-detnet-problem-statement]
Finn, N. and P. Thubert, "Deterministic Networking Problem
Statement", draft-finn-detnet-problem-statement-05 (work
in progress), March 2016.

[I-D.ietf-6tisch-6top-interface]
Wang, Q. and X. Vilajosana, "6TiSCH Operation Sublayer
(6top) Interface", draft-ietf-6tisch-6top-interface-04
(work in progress), July 2015.

[I-D.ietf-6tisch-architecture]
Thubert, P., "An Architecture for IPv6 over the TSCH mode
of IEEE 802.15.4", draft-ietf-6tisch-architecture-10 draft-ietf-6tisch-architecture-11 (work
in progress), June 2016. January 2017.

[I-D.ietf-6tisch-coap]
Sudhaakar, R. and P. Zand, "6TiSCH Resource Management and
Interaction using CoAP", draft-ietf-6tisch-coap-03 (work
in progress), March 2015.

[I-D.ietf-6tisch-terminology]
Palattella, M., Thubert, P., Watteyne, T., and Q. Wang,
"Terminology in IPv6 over the TSCH mode of IEEE
802.15.4e", draft-ietf-6tisch-terminology-07 draft-ietf-6tisch-terminology-08 (work in
progress), March December 2016.

[I-D.ietf-ipv6-multilink-subnets]
Thaler, D. and C. Huitema, "Multi-link Subnet Support in
IPv6", draft-ietf-ipv6-multilink-subnets-00 (work in
progress), July 2002.

[I-D.ietf-mpls-residence-time]
Mirsky, G., Ruffini, S., Gray, E., Drake, J., Bryant, S.,
and S. Vainshtein, "Residence Time Measurement in MPLS
network", draft-ietf-mpls-residence-time-11 draft-ietf-mpls-residence-time-15 (work in
progress), July 2016. March 2017.

[I-D.ietf-roll-rpl-industrial-applicability]
Phinney, T., Thubert, P., and R. Assimiti, "RPL
applicability in industrial networks", draft-ietf-roll-
rpl-industrial-applicability-02 (work in progress),
October 2013.

[I-D.ietf-tictoc-1588overmpls]
Davari, S., Oren, A., Bhatia, M., Roberts, P., and L.
Montini, "Transporting Timing messages over MPLS
Networks", draft-ietf-tictoc-1588overmpls-07 (work in
progress), October 2015.

[I-D.kh-spring-ip-ran-use-case]
Khasnabish, B., hu, f., and L. Contreras, "Segment Routing
in IP RAN use case", draft-kh-spring-ip-ran-use-case-02
(work in progress), November 2014.

[I-D.svshah-tsvwg-deterministic-forwarding]
Shah, S. and P. Thubert, "Deterministic Forwarding PHB",
draft-svshah-tsvwg-deterministic-forwarding-04 (work in
progress), August 2015.

[I-D.thubert-6lowpan-backbone-router]
Thubert, P., "6LoWPAN Backbone Router", draft-thubert-
6lowpan-backbone-router-03 (work in progress), February
2013.

[I-D.wang-6tisch-6top-sublayer]
Wang, Q. and X. Vilajosana, "6TiSCH Operation Sublayer
(6top)", draft-wang-6tisch-6top-sublayer-04 (work in
progress), November 2015.

[IEC-60870-5-104]
International Electrotechnical Commission, "International
Standard IEC 60870-5-104: Network access for IEC
60870-5-101 using standard transport profiles", June 2006.

[IEC61400]
"International standard 61400-25: Communications for
monitoring and control of wind power plants", June 2013.

[IEC61850-90-12]
TC57 WG10, IEC., "IEC 61850-90-12 TR: Communication
networks and systems for power utility automation - Part
90-12: Wide area network engineering guidelines", 2015.

[IEC62439-3:2012]
TC65, IEC., "IEC 62439-3: Industrial communication
networks - High availability automation networks - Part 3:
Parallel Redundancy Protocol (PRP) and High-availability
Seamless Redundancy (HSR)", 2012.

[IEEE1588]
IEEE, "IEEE Standard for a Precision Clock Synchronization
Protocol for Networked Measurement and Control Systems",
IEEE Std 1588-2008, 2008,
<http://standards.ieee.org/findstds/
standard/1588-2008.html>.

[IEEE1646]
"Communication Delivery Time Performance Requirements for
Electric Power Substation Automation", IEEE Standard
1646-2004 , Apr 2004.

[IEEE1722]
IEEE, "1722-2011 - IEEE Standard for Layer 2 Transport
Protocol for Time Sensitive Applications in a Bridged
Local Area Network", IEEE Std 1722-2011, 2011,
<http://standards.ieee.org/findstds/
standard/1722-2011.html>.

[IEEE19043]
IEEE Standards Association, "IEEE 1904.3 TF", IEEE 1904.3,
2015, <http://www.ieee1904.org/3/tf3_home.shtml>.

[IEEE802.1TSNTG]
IEEE Standards Association, "IEEE 802.1 Time-Sensitive
Networks Task Group", March 2013,
<http://www.ieee802.org/1/pages/avbridges.html>.

[IEEE802154]
IEEE standard for Information Technology, "IEEE std.
802.15.4, Part. 15.4: Wireless Medium Access Control (MAC)
and Physical Layer (PHY) Specifications for Low-Rate
Wireless Personal Area Networks".

[IEEE802154e]
IEEE standard for Information Technology, "IEEE standard
for Information Technology, IEEE std. 802.15.4, Part.
15.4: Wireless Medium Access Control (MAC) and Physical
Layer (PHY) Specifications for Low-Rate Wireless Personal
Area Networks, June 2011 as amended by IEEE std.
802.15.4e, Part. 15.4: Low-Rate Wireless Personal Area
Networks (LR-WPANs) Amendment 1: MAC sublayer", April
2012.

[IEEE8021AS]
IEEE, "Timing and Synchronizations (IEEE 802.1AS-2011)",
IEEE 802.1AS-2001, 2011,
<http://standards.ieee.org/getIEEE802/
download/802.1AS-2011.pdf>.

[IEEE8021CM]
Farkas, J., "Time-Sensitive Networking for Fronthaul",
Unapproved PAR, PAR for a New IEEE Standard;
IEEE P802.1CM, April 2015,
<http://www.ieee802.org/1/files/public/docs2015/
new-P802-1CM-dr aft-PAR-0515-v02.pdf>.

[IEEE8021TSN]
IEEE 802.1, "The charter of the TG is to provide the
specifications that will allow time-synchronized low
latency streaming services through 802 networks.", 2016,
<http://www.ieee802.org/1/pages/tsn.html>.

[IETFDetNet]
IETF, "Charter for IETF DetNet Working Group", 2015,
<https://datatracker.ietf.org/wg/detnet/charter/>.

[ISA100] ISA/ANSI, "ISA100, Wireless Systems for Automation",
<https://www.isa.org/isa100/>.

[ISA100.11a]
ISA/ANSI, "Wireless Systems for Industrial Automation:
Process Control and Related Applications - ISA100.11a-2011
- IEC 62734", 2011, <http://www.isa.org/Community/
SP100WirelessSystemsforAutomation>.

[ISO7240-16]
ISO, "ISO 7240-16:2007 Fire detection and alarm systems --
Part 16: Sound system control and indicating equipment",
2007, <http://www.iso.org/iso/
catalogue_detail.htm?csnumber=42978>.

[knx] KNX Association, "ISO/IEC 14543-3 - KNX", November 2006.

[lontalk] ECHELON, "LonTalk(R) Protocol Specification Version 3.0",
1994.

[LTE-Latency]
Johnston, S., "LTE Latency: How does it compare to other
technologies", March 2014,
<http://opensignal.com/blog/2014/03/10/
lte-latency-how-does-it-compare-to-other-technologies>.

[MEF] MEF, "Mobile Backhaul Phase 2 Amendment 1 -- Small Cells",
MEF 22.1.1, July 2014,
<http://www.mef.net/Assets/Technical_Specifications/PDF/
MEF_22.1.1.pdf>.

[METIS] METIS, "Scenarios, requirements and KPIs for 5G mobile and
wireless system", ICT-317669-METIS/D1.1 ICT-
317669-METIS/D1.1, April 2013, <https://www.metis2020.com/
wp-content/uploads/deliverables/METIS_D1.1_v1.pdf>.

[modbus] Modbus Organization, "MODBUS APPLICATION PROTOCOL
SPECIFICATION V1.1b", December 2006.

[MODBUS] Modbus Organization, Inc., "MODBUS Application Protocol
Specification", Apr 2012.

[net5G] Ericsson, "5G Radio Access, Challenges for 2020 and
Beyond", Ericsson white paper wp-5g, June 2013,
<http://www.ericsson.com/res/docs/whitepapers/wp-5g.pdf>.

[NGMN] NGMN Alliance, "5G White Paper", NGMN 5G White Paper v1.0,
February 2015, <https://www.ngmn.org/uploads/media/
NGMN_5G_White_Paper_V1_0.pdf>.

[NGMN-fronth]
NGMN Alliance, "Fronthaul Requirements for C-RAN", March
2015, <https://www.ngmn.org/uploads/media/NGMN_RANEV_D1_C-
RAN_Fronthaul_Requirements_v1.0.pdf>.

[OPCXML] OPC Foundation, "OPC XML-Data Access Specification", Dec
2004.

[PCE] IETF, "Path Computation Element",
<https://datatracker.ietf.org/doc/charter-ietf-pce/>.

[profibus]
IEC, "IEC 61158 Type 3 - Profibus DP", January 2001.

[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<http://www.rfc-editor.org/info/rfc2119>.

[RFC2460] Deering, S. and R. Hinden, "Internet Protocol, Version 6
(IPv6) Specification", RFC 2460, DOI 10.17487/RFC2460,
December 1998, <http://www.rfc-editor.org/info/rfc2460>.

[RFC2474] Nichols, K., Blake, S., Baker, F., and D. Black,
"Definition of the Differentiated Services Field (DS
Field) in the IPv4 and IPv6 Headers", RFC 2474,
DOI 10.17487/RFC2474, December 1998,
<http://www.rfc-editor.org/info/rfc2474>.

[RFC3031] Rosen, E., Viswanathan, A., and R. Callon, "Multiprotocol
Label Switching Architecture", RFC 3031,
DOI 10.17487/RFC3031, January 2001,
<http://www.rfc-editor.org/info/rfc3031>.

[RFC3209] Awduche, D., Berger, L., Gan, D., Li, T., Srinivasan, V.,
and G. Swallow, "RSVP-TE: Extensions to RSVP for LSP
Tunnels", RFC 3209, DOI 10.17487/RFC3209, December 2001,
<http://www.rfc-editor.org/info/rfc3209>.

[RFC3393] Demichelis, C. and P. Chimento, "IP Packet Delay Variation
Metric for IP Performance Metrics (IPPM)", RFC 3393,
DOI 10.17487/RFC3393, November 2002,
<http://www.rfc-editor.org/info/rfc3393>.

[RFC3411] Harrington, D., Presuhn, R., and B. Wijnen, "An
Architecture for Describing Simple Network Management
Protocol (SNMP) Management Frameworks", STD 62, RFC 3411,
DOI 10.17487/RFC3411, December 2002,
<http://www.rfc-editor.org/info/rfc3411>.

[RFC3444] Pras, A. and J. Schoenwaelder, "On the Difference between
Information Models and Data Models", RFC 3444,
DOI 10.17487/RFC3444, January 2003,
<http://www.rfc-editor.org/info/rfc3444>.

[RFC3972] Aura, T., "Cryptographically Generated Addresses (CGA)",
RFC 3972, DOI 10.17487/RFC3972, March 2005,
<http://www.rfc-editor.org/info/rfc3972>.

[RFC3985] Bryant, S., Ed. and P. Pate, Ed., "Pseudo Wire Emulation
Edge-to-Edge (PWE3) Architecture", RFC 3985,
DOI 10.17487/RFC3985, March 2005,
<http://www.rfc-editor.org/info/rfc3985>.

[RFC4291] Hinden, R. and S. Deering, "IP Version 6 Addressing
Architecture", RFC 4291, DOI 10.17487/RFC4291, February
2006, <http://www.rfc-editor.org/info/rfc4291>.

[RFC4553] Vainshtein, A., Ed. and YJ. Stein, Ed., "Structure-
Agnostic Time Division Multiplexing (TDM) over Packet
(SAToP)", RFC 4553, DOI 10.17487/RFC4553, June 2006,
<http://www.rfc-editor.org/info/rfc4553>.

[RFC4903] Thaler, D., "Multi-Link Subnet Issues", RFC 4903,
DOI 10.17487/RFC4903, June 2007,
<http://www.rfc-editor.org/info/rfc4903>.

[RFC4919] Kushalnagar, N., Montenegro, G., and C. Schumacher, "IPv6
over Low-Power Wireless Personal Area Networks (6LoWPANs):
Overview, Assumptions, Problem Statement, and Goals",
RFC 4919, DOI 10.17487/RFC4919, August 2007,
<http://www.rfc-editor.org/info/rfc4919>.

[RFC5086] Vainshtein, A., Ed., Sasson, I., Metz, E., Frost, T., and
P. Pate, "Structure-Aware Time Division Multiplexed (TDM)
Circuit Emulation Service over Packet Switched Network
(CESoPSN)", RFC 5086, DOI 10.17487/RFC5086, December 2007,
<http://www.rfc-editor.org/info/rfc5086>.

[RFC5087] Stein, Y(J)., Shashoua, R., Insler, R., and M. Anavi,
"Time Division Multiplexing over IP (TDMoIP)", RFC 5087,
DOI 10.17487/RFC5087, December 2007,
<http://www.rfc-editor.org/info/rfc5087>.

[RFC6282] Hui, J., Ed. and P. Thubert, "Compression Format for IPv6
Datagrams over IEEE 802.15.4-Based Networks", RFC 6282,
DOI 10.17487/RFC6282, September 2011,
<http://www.rfc-editor.org/info/rfc6282>.

[RFC6550] Winter, T., Ed., Thubert, P., Ed., Brandt, A., Hui, J.,
Kelsey, R., Levis, P., Pister, K., Struik, R., Vasseur,
JP., and R. Alexander, "RPL: IPv6 Routing Protocol for
Low-Power and Lossy Networks", RFC 6550,
DOI 10.17487/RFC6550, March 2012,
<http://www.rfc-editor.org/info/rfc6550>.

[RFC6551] Vasseur, JP., Ed., Kim, M., Ed., Pister, K., Dejean, N.,
and D. Barthel, "Routing Metrics Used for Path Calculation
in Low-Power and Lossy Networks", RFC 6551,
DOI 10.17487/RFC6551, March 2012,
<http://www.rfc-editor.org/info/rfc6551>.

[RFC6775] Shelby, Z., Ed., Chakrabarti, S., Nordmark, E., and C.
Bormann, "Neighbor Discovery Optimization for IPv6 over
Low-Power Wireless Personal Area Networks (6LoWPANs)",
RFC 6775, DOI 10.17487/RFC6775, November 2012,
<http://www.rfc-editor.org/info/rfc6775>.

[RFC7554] Watteyne, T., Ed., Palattella, M., and L. Grieco, "Using
IEEE 802.15.4e Time-Slotted Channel Hopping (TSCH) in the
Internet of Things (IoT): Problem Statement", RFC 7554,
DOI 10.17487/RFC7554, May 2015,
<http://www.rfc-editor.org/info/rfc7554>.

[Spe09] Sperotto, A., Sadre, R., Vliet, F., and A. Pras, "A First
Look into SCADA Network Traffic", IP Operations and
Management, p. 518-521. , June 2009.

[SRP_LATENCY]
Gunther, C., "Specifying SRP Latency", 2014,
<http://www.ieee802.org/1/files/public/docs2014/
cc-cgunther-acceptable-latency-0314-v01.pdf>.

[STUDIO_IP]
Mace, G., "IP Networked Studio Infrastructure for
Synchronized & Real-Time Multimedia Transmissions", 2007,
<http://www.ieee802.org/1/files/public/docs2047/
avb-mace-ip-networked-studio-infrastructure-0107.pdf>.

[SyncE] ITU-T, "G.8261 : Timing and synchronization aspects in
packet networks", Recommendation G.8261, August 2013,
<http://www.itu.int/rec/T-REC-G.8261>.

[TEAS] IETF, "Traffic Engineering Architecture and Signaling",
<https://datatracker.ietf.org/doc/charter-ietf-teas/>.

[TS23401] 3GPP, "General Packet Radio Service (GPRS) enhancements
for Evolved Universal Terrestrial Radio Access Network
(E-UTRAN) access", 3GPP TS 23.401 10.10.0, March 2013.

[TS25104] 3GPP, "Base Station (BS) radio transmission and reception
(FDD)", 3GPP TS 25.104 3.14.0, March 2007.

[TS36104] 3GPP, "Evolved Universal Terrestrial Radio Access
(E-UTRA); Base Station (BS) radio transmission and
reception", 3GPP TS 36.104 10.11.0, July 2013.

[TS36133] 3GPP, "Evolved Universal Terrestrial Radio Access
(E-UTRA); Requirements for support of radio resource
management", 3GPP TS 36.133 12.7.0, April 2015.

[TS36211] 3GPP, "Evolved Universal Terrestrial Radio Access
(E-UTRA); Physical channels and modulation", 3GPP
TS 36.211 10.7.0, March 2013.

[TS36300] 3GPP, "Evolved Universal Terrestrial Radio Access (E-UTRA)
and Evolved Universal Terrestrial Radio Access Network
(E-UTRAN); Overall description; Stage 2", 3GPP TS 36.300
10.11.0, September 2013.

[TSNTG] IEEE Standards Association, "IEEE 802.1 Time-Sensitive
Networks Task Group", 2013,
<http://www.IEEE802.org/1/pages/avbridges.html>.

[UHD-video]
Holub, P., "Ultra-High Definition Videos and Their
Applications over the Network", The 7th International
Symposium on VICTORIES Project PetrHolub_presentation,
October 2014, <http://www.aist-
victories.org/jp/7th_sympo_ws/PetrHolub_presentation.pdf>.

[WirelessHART]
www.hartcomm.org, "Industrial Communication Networks -
Wireless Communication Network and Communication Profiles
- WirelessHART - IEC 62591", 2010.

Authors' Addresses

Ethan Grossman (editor)
Dolby Laboratories, Inc.
1275 Market Street
San Francisco, CA 94103
USA

Phone: +1 415 645 4726
Email: ethan.grossman@dolby.com
URI: http://www.dolby.com

Craig Gunther
Harman International
10653 South River Front Parkway
South Jordan, UT 84095
USA

Phone: +1 801 568-7675
Email: craig.gunther@harman.com
URI: http://www.harman.com
Pascal Thubert
Cisco Systems, Inc
Building D
45 Allee des Ormes - BP1200
MOUGINS - Sophia Antipolis 06254
FRANCE

Phone: +33 497 23 26 34
Email: pthubert@cisco.com

Patrick Wetterwald
Cisco Systems
45 Allees des Ormes
Mougins 06250
FRANCE

Phone: +33 4 97 23 26 36
Email: pwetterw@cisco.com

Jean Raymond
Hydro-Quebec
1500 University
Montreal H3A3S7
Canada

Phone: +1 514 840 3000
Email: raymond.jean@hydro.qc.ca

Jouni Korhonen
Broadcom Corporation
3151 Zanker Road
San Jose, CA 95134
USA

Email: jouni.nospam@gmail.com

Yu Kaneko
Toshiba
1 Komukai-Toshiba-cho, Saiwai-ku, Kasasaki-shi
Kanagawa, Japan

Email: yu1.kaneko@toshiba.co.jp
Subir Das
Applied Communication Sciences
150 Mount Airy Road, Basking Ridge
New Jersey, 07920, USA

Email: sdas@appcomsci.com

Yiyong Zha
Huawei Technologies

Email: zhayiyong@huawei.com

Balazs Varga
Ericsson
Konyves Kalman krt. 11/B
Budapest 1097
Hungary

Email: balazs.a.varga@ericsson.com

Janos Farkas
Ericsson
Konyves Kalman krt. 11/B
Budapest 1097
Hungary

Email: janos.farkas@ericsson.com

Franz-Josef Goetz
Siemens
Gleiwitzerstr. 555
Nurnberg 90475
Germany

Email: franz-josef.goetz@siemens.com

Juergen Schmitt
Siemens
Gleiwitzerstr. 555
Nurnberg 90475
Germany

Email: juergen.jues.schmitt@siemens.com
Xavier Vilajosana
Worldsensing
483 Arago
Barcelona, Catalonia 08013
Spain

Email: xvilajosana@worldsensing.com

Toktam Mahmoodi
King's College London
Strand, London WC2R 2LS
London, London WC2R 2LS
United Kingdom

Email: toktam.mahmoodi@kcl.ac.uk

Spiros Spirou
Intracom Telecom
19.7 km Markopoulou Ave.
Peania, Attiki 19002
Greece

Email: spis@intracom-telecom.com

Petra Vizarreta
Technical University of Munich, TUM
Maxvorstadt, ArcisstraBe 21
Munich, Germany 80333
Germany

Email: petra.vizarreta@lkn.ei.tum.de