draft-xu-mpls-sr-over-ip-00.txt   draft-xu-mpls-sr-over-ip-01.txt 
Network Working Group X. Xu Network Working Group X. Xu
Internet-Draft Alibaba Internet-Draft Alibaba
Intended status: Standards Track S. Bryant Intended status: Standards Track S. Bryant
Expires: September 2, 2018 Huawei Expires: December 3, 2018 Huawei
A. Farrel A. Farrel
Juniper Juniper
A. Bashandy S. Hassan
Cisco Cisco
W. Henderickx W. Henderickx
Nokia Nokia
Z. Li Z. Li
Huawei Huawei
March 1, 2018 June 1, 2018
SR-MPLS over IP SR-MPLS over IP
draft-xu-mpls-sr-over-ip-00 draft-xu-mpls-sr-over-ip-01
Abstract Abstract
MPLS Segment Routing (SR-MPLS in short) is an MPLS data plane-based MPLS Segment Routing (SR-MPLS in short) is an MPLS data plane-based
source routing paradigm in which the sender of a packet is allowed to source routing paradigm in which the sender of a packet is allowed to
partially or completely specify the route the packet takes through partially or completely specify the route the packet takes through
the network by imposing stacked MPLS labels on the packet. SR-MPLS the network by imposing stacked MPLS labels on the packet. SR-MPLS
could be leveraged to realize a source routing mechanism across MPLS, could be leveraged to realize a source routing mechanism across MPLS,
IPv4, and IPv6 data planes by using an MPLS label stack as a source IPv4, and IPv6 data planes by using an MPLS label stack as a source
routing instruction set while preserving backward compatibility with routing instruction set while preserving backward compatibility with
SR-MPLS. SR-MPLS.
This document describes how SR-MPLS capable routers and IP-only This document describes how SR-MPLS capable routers and IP-only
routers can seamlessly co-exist and interoperate through the use of routers can seamlessly co-exist and interoperate through the use of
SR-MPLS label stacks and IP encapsulation/tunnelling such as MPLS-in- SR-MPLS label stacks and IP encapsulation/tunneling such as MPLS-in-
UDP [RFC7510]. UDP as defined in RFC 7510.
Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in BCP
14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.
Status of This Memo Status of This Memo
This Internet-Draft is submitted in full conformance with the This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79. provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
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This Internet-Draft will expire on December 3, 2018.
This Internet-Draft will expire on September 2, 2018.
Copyright Notice Copyright Notice
Copyright (c) 2018 IETF Trust and the persons identified as the Copyright (c) 2018 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
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described in the Simplified BSD License. described in the Simplified BSD License.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Use Cases . . . . . . . . . . . . . . . . . . . . . . . . . . 4 3. Use Cases . . . . . . . . . . . . . . . . . . . . . . . . . . 3
4. Procedures of SR-MPLS over IP . . . . . . . . . . . . . . . . 5 4. Procedures of SR-MPLS over IP . . . . . . . . . . . . . . . . 5
4.1. Forwarding Entry Construction . . . . . . . . . . . . . . 5 4.1. Forwarding Entry Construction . . . . . . . . . . . . . . 5
4.2. Packet Forwarding Procedures . . . . . . . . . . . . . . 7 4.2. Packet Forwarding Procedures . . . . . . . . . . . . . . 7
4.2.1. Packet Forwarding with Penultimate Hop Popping . . . 7 4.2.1. Packet Forwarding with Penultimate Hop Popping . . . 8
4.2.2. Packet Forwarding without Penultimate Hop Popping . . 8 4.2.2. Packet Forwarding without Penultimate Hop Popping . . 9
4.2.3. Additional Forwarding Procedures . . . . . . . . . . 9 4.2.3. Additional Forwarding Procedures . . . . . . . . . . 10
5. Forwarding Details of SR-MPLS over UDP . . . . . . . . . . . 10 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 11
5.1. Domain Ingress Nodes . . . . . . . . . . . . . . . . . . 11 6. Security Considerations . . . . . . . . . . . . . . . . . . . 12
5.2. Legacy Transit Nodes . . . . . . . . . . . . . . . . . . 11 7. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 12
5.3. On-Path Pass-Through SR Nodes . . . . . . . . . . . . . . 12 8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 13
5.4. SR Transit Nodes . . . . . . . . . . . . . . . . . . . . 12 9. References . . . . . . . . . . . . . . . . . . . . . . . . . 13
5.5. Penultimate SR Transit Nodes . . . . . . . . . . . . . . 13 9.1. Normative References . . . . . . . . . . . . . . . . . . 13
5.5.1. A Note on Segment Routing Paths and Penultimate Hop 9.2. Informative References . . . . . . . . . . . . . . . . . 15
Popping . . . . . . . . . . . . . . . . . . . . . . . 14 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 15
5.6. Domain Egress Nodes . . . . . . . . . . . . . . . . . . . 14
6. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 15
7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 17
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 17
9. Security Considerations . . . . . . . . . . . . . . . . . . . 17
10. References . . . . . . . . . . . . . . . . . . . . . . . . . 17
10.1. Normative References . . . . . . . . . . . . . . . . . . 17
10.2. Informative References . . . . . . . . . . . . . . . . . 18
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 19
1. Introduction 1. Introduction
MPLS Segment Routing (SR-MPLS in short) MPLS Segment Routing (SR-MPLS in short)
[I-D.ietf-spring-segment-routing-mpls] is an MPLS data plane-based [I-D.ietf-spring-segment-routing-mpls] is an MPLS data plane-based
source routing paradigm in which the sender of a packet is allowed to source routing paradigm in which the sender of a packet is allowed to
partially or completely specify the route the packet takes through partially or completely specify the route the packet takes through
the network by imposing stacked MPLS labels on the packet. SR-MPLS the network by imposing stacked MPLS labels on the packet. SR-MPLS
could be leveraged to realize a source routing mechanism across MPLS, could be leveraged to realize a source routing mechanism across MPLS,
IPv4, and IPv6 data planes by using an MPLS label stack as a source IPv4, and IPv6 data planes by using an MPLS label stack as a source
routing instruction set while preserving backward compatibility with routing instruction set while preserving backward compatibility with
SR-MPLS. More specifically, the source routing instruction set SR-MPLS. More specifically, the source routing instruction set
information contained in a source routed packet could be uniformly information contained in a source routed packet could be uniformly
encoded as an MPLS label stack no matter whether the underlay is encoded as an MPLS label stack no matter whether the underlay is
IPv4, IPv6, or MPLS. IPv4, IPv6, or MPLS.
This document describes how SR-MPLS capable routers and IP-only This document describes how SR-MPLS capable routers and IP-only
routers can seamlessly co-exist and interoperate through the use of routers can seamlessly co-exist and interoperate through the use of
SR-MPLS label stacks and IP encapsulation/tunnelling such as MPLS-in- SR-MPLS label stacks and IP encapsulation/tunneling such as MPLS-in-
UDP [RFC7510]. UDP [RFC7510].
Although the source routing instructions are encoded as MPLS labels, Although the source routing instructions are encoded as MPLS labels,
this is a hardware convenience rather than an indication that the this is a hardware convenience rather than an indication that the
whole MPLS protocol stack needs to be deployed. In particular, the whole MPLS protocol stack needs to be deployed. In particular, the
MPLS control protocols are not used in this or any other form of SR- MPLS control protocols are not used in this or any other form of SR-
MPLS. MPLS.
Section 3 describes various use cases for the tunneling SR-MPLS over Section 3 describes various use cases for the tunneling SR-MPLS over
IP. Section 4 describes a typical application scenario and how the IP. Section 4 describes a typical application scenario and how the
packet forwarding happens. Section 5 describes the forwarding packet forwarding happens.
procedures of different elements when UDP encapsulation is adopted
for source routing.
2. Terminology 2. Terminology
This memo makes use of the terms defined in [RFC3031] and This memo makes use of the terms defined in [RFC3031] and
[I-D.ietf-spring-segment-routing-mpls]. [I-D.ietf-spring-segment-routing-mpls].
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in BCP
14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.
3. Use Cases 3. Use Cases
Tunnelling SR-MPLS using IPv4 and/or IPv6 tunnels is useful at least Tunneling SR-MPLS using IPv4 and/or IPv6 tunnels is useful at least
in the following use cases: in the following use cases:
o Incremental deployment of the SR-MPLS technology may be o Incremental deployment of the SR-MPLS technology may be
facilitated by tunnelling SR-MPLS packets across parts of a facilitated by tunneling SR-MPLS packets across parts of a network
network that are not SR-MPLS enabled using an IP tunneling that are not SR-MPLS enabled using an IP tunneling mechanism such
mechanism such as MPLS-in-UDP [RFC7510]. The tunnel destination as MPLS-in-UDP [RFC7510]. The tunnel destination address is the
address is the address of the next SR-MPLS-capable node along the address of the next SR-MPLS-capable node along the path (i.e., the
path (i.e., the egress of the active node segment). This is shown egress of the active node segment). This is shown in Figure 1.
in Figure 1.
________________________ ________________________
_______ ( ) _______ _______ ( ) _______
( ) ( IP Network ) ( ) ( ) ( IP Network ) ( )
( SR-MPLS ) ( ) ( SR-MPLS ) ( SR-MPLS ) ( ) ( SR-MPLS )
( Network ) ( ) ( Network ) ( Network ) ( ) ( Network )
( -------- -------- ) ( -------- -------- )
( | Border | SR-in-UDP Tunnel | Border | ) ( | Border | SR-in-UDP Tunnel | Border | )
( | Router |========================| Router | ) ( | Router |========================| Router | )
( | R1 | | R2 | ) ( | R1 | | R2 | )
( -------- -------- ) ( -------- -------- )
( ) ( ) ( ) ( ) ( ) ( )
( ) ( ) ( ) ( ) ( ) ( )
(_______) ( ) (_______) (_______) ( ) (_______)
(________________________) (________________________)
Figure 1: SR-MPLS in UDP to Tunnel Between SR-MPLS Sites Figure 1: SR-MPLS in UDP to Tunnel Between SR-MPLS Sites
o If encoding of entropy is desired, IP tunneling mechanims that o If encoding of entropy is desired, IP tunneling mechanisms that
allow encoding of entrpopy, such as MPLS-in-UDP encapsulation allow encoding of entropy, such as MPLS-in-UDP encapsulation
[RFC7510] where the source port of the UDP header is used as an [RFC7510] where the source port of the UDP header is used as an
entropy field, may be used to maximize the untilization of ECMP entropy field, may be used to maximize the utilization of ECMP
and/or UCMP, specially when it is difficult to make use of entropy and/or UCMP, specially when it is difficult to make use of entropy
label mechanism. Refer to [I-D.ietf-mpls-spring-entropy-label]) label mechanism. Refer to [I-D.ietf-mpls-spring-entropy-label])
for more discussion about using entropy label in SR-MPLS. for more discussion about using entropy label in SR-MPLS.
o Tunneling MPLS into IP provides a transition technology that o Tunneling MPLS into IP provides a technology that enables SR in an
enables SR in an IPv4 and/or IPv6 network where many routers have IPv4 and/or IPv6 network where the routers do not support SRv6
not yet been upgraded to have SRv6 capabilities capabilities [I-D.ietf-6man-segment-routing-header] and where MPLS
[I-D.ietf-6man-segment-routing-header]. It could be deployed as forwarding is not an option. This is shown in Figure Figure 2.
an interim until full featured SRv6 is available on more
platforms. This is shown in Figure 2.
__________________________________ __________________________________
__( IP Network )__ __( IP Network )__
__( )__ __( )__
( -- -- -- ) ( -- -- -- )
-------- -- -- |SR| -- |SR| -- |SR| -- -------- -------- -- -- |SR| -- |SR| -- |SR| -- --------
| Ingress| |IR| |IR| | | |IR| | | |IR| | | |IR| | Egress | | Ingress| |IR| |IR| | | |IR| | | |IR| | | |IR| | Egress |
--->| Router |===========| |======| |======| |======| Router |---> --->| Router |===========| |======| |======| |======| Router |--->
| SR | | | | | | | | | | | | | | | | | | SR | | SR | | | | | | | | | | | | | | | | | | SR |
-------- -- -- | | -- | | -- | | -- -------- -------- -- -- | | -- | | -- | | -- --------
skipping to change at page 5, line 46 skipping to change at page 5, line 46
4.1. Forwarding Entry Construction 4.1. Forwarding Entry Construction
This sub-section describes the how to construct the forwarding This sub-section describes the how to construct the forwarding
information base (FIB) entry on an SR-MPLS-capable router when some information base (FIB) entry on an SR-MPLS-capable router when some
or all of the next-hops along the shortest path towards a prefix-SID or all of the next-hops along the shortest path towards a prefix-SID
are IP-only routers. are IP-only routers.
Consider router A that receives a labeled packet with top label L(E) Consider router A that receives a labeled packet with top label L(E)
that corresponds to the prefix-SID SID(E) of prefix P(E) advertised that corresponds to the prefix-SID SID(E) of prefix P(E) advertised
by router E. Suppose the ith next-hop router (termed NHi) along the by router E. Suppose the ith next-hop router (termed NHi) along the
shortest path from router A toward SID(E) is not SR-MPLS capable. shortest path from router A toward SID(E) is not SR-MPLS capable
That is both routers A and E are SR-MPLS capable, but some router NHi while both routers A and E are SR-MPLS capable. The following
along the shortest path from A to E is not SR-MPLS capable. The processing steps apply:
following processing steps apply:
o Router E is SR-MPLS capable so it advertises the SR-Capabilities o Router E is SR-MPLS capable so it advertises the SR-Capabilities
sub-TLV including the SRGB as described in sub-TLV including the SRGB as described in
[I-D.ietf-ospf-segment-routing-extensions] and [I-D.ietf-ospf-segment-routing-extensions] and
[I-D.ietf-isis-segment-routing-extensions]. [I-D.ietf-isis-segment-routing-extensions].
o Router E advertises the prefix-SID SID(E) of prefix P(E) so MUST o Router E advertises the prefix-SID SID(E) of prefix P(E) so MUST
also advertise the encapsulation endpoint and the tunnel type of also advertise the encapsulation endpoint and the tunnel type of
any tunnel used to reach E. It does this using the mechanisms any tunnel used to reach E. It does this using the mechanisms
described in [I-D.ietf-isis-encapsulation-cap] or described in [I-D.ietf-isis-encapsulation-cap] or
skipping to change at page 7, line 18 skipping to change at page 7, line 18
bound of the SRGB of E bound of the SRGB of E
* Encapsulate the packet according to the encapsulation * Encapsulate the packet according to the encapsulation
advertised in [I-D.ietf-isis-encapsulation-cap] or advertised in [I-D.ietf-isis-encapsulation-cap] or
[I-D.ietf-ospf-encapsulation-cap] [I-D.ietf-ospf-encapsulation-cap]
* Send the packet towards the next hop NHi. * Send the packet towards the next hop NHi.
4.2. Packet Forwarding Procedures 4.2. Packet Forwarding Procedures
[RFC7510] specifies an IP-based encapsulation for MPLS, i.e., MPLS-
in-UDP, which is applicable in some circumstances where IP-based
encapsulation for MPLS is required and further fine-grained load
balancing of MPLS packets over IP networks over Equal-Cost Multipath
(ECMP) and/or Link Aggregation Groups (LAGs) is required as well.
This section provides details about the forwarding procedure when
when UDP encapsulation is adopted for SR-MPLS over IP.
Nodes that are SR-MPLS capable can process SR-MPLS packets. Not all
of the nodes in an SR-MPLS domain are SR-MPLS capable. Some nodes
may be "legacy routers" that cannot handle SR-MPLS packets but can
forward IP packets. An SR-MPLS-capable node may advertise its
capabilities using the IGP as described in Section 4. There are six
types of node in an SR-MPLS domain:
o Domain ingress nodes that receive packets and encapsulate them for
transmission across the domain. Those packets may be any payload
protocol including native IP packets or packets that are already
MPLS encapsulated.
o Legacy transit nodes that are IP routers but that are not SR-MPLS
capable (i.e., are not able to perform segment routing).
o Transit nodes that are SR-MPLS capable but that are not identified
by a SID in the SID stack.
o Transit nodes that are SR-MPLS capable and need to perform SR-MPLS
routing because they are identified by a SID in the SID stack.
o The penultimate SR-MPLS capable node on the path that processes
the last SID on the stack on behalf of the domain egress node.
o The domain egress node that forwards the payload packet for
ultimate delivery.
4.2.1. Packet Forwarding with Penultimate Hop Popping 4.2.1. Packet Forwarding with Penultimate Hop Popping
The description in this section assumes that the label associated The description in this section assumes that the label associated
with each prefix-SID is advertised by the owner of the prefix-SID is with each prefix-SID is advertised by the owner of the prefix-SID is
a Penultimate Hop Popping (PHP) label. That is, the NP flag in OSPF a Penultimate Hop Popping (PHP) label. That is, the NP flag in OSPF
or the P flag in ISIS associated with the prefix SID is not set. or the P flag in ISIS associated with the prefix SID is not set.
+-----+ +-----+ +-----+ +-----+ +-----+ +-----+ +-----+ +-----+ +-----+ +-----+
| A +-------+ B +-------+ C +--------+ D +--------+ H | | A +-------+ B +-------+ C +--------+ D +--------+ H |
+-----+ +--+--+ +--+--+ +--+--+ +-----+ +-----+ +--+--+ +--+--+ +--+--+ +-----+
skipping to change at page 7, line 48 skipping to change at page 8, line 35
+--------+ +--------+ +--------+ +--------+ +--------+ +--------+
| L(G) | | UDP | | UDP | | L(G) | | UDP | | UDP |
+--------+ +--------+ +--------+ +--------+ +--------+ +--------+
| L(H) | | L(H) | |Exp Null| | L(H) | | L(H) | |Exp Null|
+--------+ +--------+ +--------+ +--------+ +--------+ +--------+
| Packet | ---> | Packet | ---> | Packet | | Packet | ---> | Packet | ---> | Packet |
+--------+ +--------+ +--------+ +--------+ +--------+ +--------+
Figure 3: Packet Forwarding Example with PHP Figure 3: Packet Forwarding Example with PHP
In the example shown in Figure 3, assume that routers A, E, G, and H In the example shown in Figure 3, assume that routers A, E, G and H
are SR-MPLS-capable while the remaining routers (B, C, D, and F) are are SR-MPLS-capable while the remaining routers (B, C, D and F) are
only capable of forwarding IP packets. Routers A, E, G, and H only capable of forwarding IP packets. Routers A, E, G, and H
advertise their Segment Routing related information via IS-IS or advertise their Segment Routing related information via IS-IS or
OSPF. OSPF.
Now assume that router A wants to send a packet via the explicit path Now assume that router A (the Domain ingress) wants to send a packet
{E->G->H}. Router A will impose an MPLS label stack corresponding to to router H (the Domain egress) via the explicit path {E->G->H}.
that explicit path on the packet. Since the next hop toward router E Router A will impose an MPLS label stack on the packet that
is only IP-capable, router A replaces the top label (that indicated corresponds to that explicit path. Since the next hop toward router
router E) with a UDP-based tunnel for MPLS (i.e., MPLS-over-UDP E is only IP-capable (B is a legacy transit node), router A replaces
[RFC7510]) to router E and then sends the packet. In other words, the top label (that indicated router E) with a UDP-based tunnel for
router A pops the top label and then encapsulates the MPLS packet in MPLS (i.e., MPLS-over-UDP [RFC7510]) to router E and then sends the
a UDP tunnel to router E. packet. In other words, router A pops the top label and then
encapsulates the MPLS packet in a UDP tunnel to router E.
When the IP-encapsulated MPLS packet arrives at router E, router E When the IP-encapsulated MPLS packet arrives at router E (which is an
strips the IP-based tunnel header and then process the decapsulated SR-MPLS-capable transit node), router E strips the IP-based tunnel
MPLS packet. The top label indicates that the packet must be header and then process the decapsulated MPLS packet. The top label
forwarded toward router G. Since the next hop toward router G is indicates that the packet must be forwarded toward router G. Since
only IP-capable, router E replaces the current top label with an the next hop toward router G is only IP-capable, router E replaces
MPLS-over-UDP tunnel toward router G and sends it out. That is, the current top label with an MPLS-over-UDP tunnel toward router G
router E pops the top label and then encapsulates the MPLS packet in and sends it out. That is, router E pops the top label and then
a UDP tunnel to router G. encapsulates the MPLS packet in a UDP tunnel to router G.
When the packet arrives at router G, router G will strip the IP-based When the packet arrives at router G, router G will strip the IP-based
tunnel header and then process the decapsulated MPLS packet. The top tunnel header and then process the decapsulated MPLS packet. The top
label indicates that the packet must be forwarded toward router H. label indicates that the packet must be forwarded toward router H.
Since the next hop toward router H is only IP-capable, router G would Since the next hop toward router H is only IP-capable (D is a legacy
replace the current top label with an MPLS-over-UDP tunnel toward transit router), router G would replace the current top label with an
router H and send it out. However, this would leave the original MPLS-over-UDP tunnel toward router H and send it out. However, since
router G reaches the bottom of the label stack (G is the penultimate
SR-MPLS capable node on the path) this would leave the original
packet that router A wanted to send to router H encapsulated in UDP packet that router A wanted to send to router H encapsulated in UDP
as if it was MPLS even though the original packet could have been any as if it was MPLS (i.e., with a UDP header and destination port
indicating MPLS) even though the original packet could have been any
protocol. That is, the final SR-MPLS has been popped exposing the protocol. That is, the final SR-MPLS has been popped exposing the
payload packet. payload packet.
To handle this, when a router (here it is router G) pops the final To handle this, when a router (here it is router G) pops the final
SR-MPLS label, it inserts an explicit null label [RFC3032] before SR-MPLS label, it inserts an explicit null label [RFC3032] before
encapsulating the packet with an MPLS-over-UDP tunnel toward router H encapsulating the packet in an MPLS-over-UDP tunnel toward router H
and sending it out. That is, router G pops the top label, discovers and sending it out. That is, router G pops the top label, discovers
it has reached the bottom of stack, pushes an explicit null label, it has reached the bottom of stack, pushes an explicit null label,
and then encapsulates the MPLS packet in a UDP tunnel to router H. and then encapsulates the MPLS packet in a UDP tunnel to router H.
4.2.2. Packet Forwarding without Penultimate Hop Popping 4.2.2. Packet Forwarding without Penultimate Hop Popping
Figure 4 demonstrates the packet walk in the case where the label Figure 4 demonstrates the packet walk in the case where the label
associated with each prefix-SID advertised by the owner of the associated with each prefix-SID advertised by the owner of the
prefix-SID is not a Penultimate Hop Popping (PHP) label (i.e., the prefix-SID is not a Penultimate Hop Popping (PHP) label (i.e., the
the NP flag in OSPF or the P flag in ISIS associated with the prefix the NP flag in OSPF or the P flag in ISIS associated with the prefix
SID is set). SID is set). Apart from the PHP function the roles of the routers is
unchanged from Section 4.2.1.
+-----+ +-----+ +-----+ +-----+ +-----+ +-----+ +-----+ +-----+ +-----+ +-----+
| A +-------+ B +-------+ C +--------+ D +--------+ H | | A +-------+ B +-------+ C +--------+ D +--------+ H |
+-----+ +--+--+ +--+--+ +--+--+ +-----+ +-----+ +--+--+ +--+--+ +--+--+ +-----+
| | | | | |
| | | | | |
+--+--+ +--+--+ +--+--+ +--+--+ +--+--+ +--+--+
| E +-------+ F +--------+ G | | E +-------+ F +--------+ G |
+-----+ +-----+ +-----+ +-----+ +-----+ +-----+
skipping to change at page 9, line 32 skipping to change at page 10, line 32
+--------+ +--------+ +--------+ +--------+ +--------+ +--------+
| L(H) | | L(H) | | L(H) | | L(H) | | L(H) | | L(H) |
+--------+ +--------+ +--------+ +--------+ +--------+ +--------+
| Packet | ---> | Packet | ---> | Packet | | Packet | ---> | Packet | ---> | Packet |
+--------+ +--------+ +--------+ +--------+ +--------+ +--------+
Figure 4: Packet Forwarding Example without PHP Figure 4: Packet Forwarding Example without PHP
As can be seen from the figure, the SR-MPLS label for each segment is As can be seen from the figure, the SR-MPLS label for each segment is
left in place until the end of the segment where it is popped and the left in place until the end of the segment where it is popped and the
next instruction is processed. Further description can be found in next instruction is processed.
Section 5.
4.2.3. Additional Forwarding Procedures 4.2.3. Additional Forwarding Procedures
Although the description in the previous two sections is based on the Non-MPLS Interfaces: Although the description in the previous two
use of prefix-SIDs, tunneling SR-MPLS packets are useful when the top sections is based on the use of prefix-SIDs, tunneling SR-MPLS
label of a received SR-MPLS packet indicates an adjacncy-SID and the packets is useful when the top label of a received SR-MPLS packet
corresponding adjacent node to that adjacency-SID is not capable of indicates an adjacency-SID and the corresponding adjacent node to
MPLS forwarding but can still process SR-MPLS packets. In this that adjacency-SID is not capable of MPLS forwarding but can still
scenario the top label would be replaced by an IP tunnel toward that process SR-MPLS packets. In this scenario the top label would be
adjacent node and then forwarded over the corresponding link replaced by an IP tunnel toward that adjacent node and then
indicated by the adjacency-SID. forwarded over the corresponding link indicated by the adjacency-
SID.
When encapsulating an MPLS packet with an IP tunnel header that is
capable of encoding entropy (such as [RFC7510]), the corresponding
entropy field (the source port in case UDP tunnel) MAY be filled with
an entropy value that is generated by the encapsulator to uniquely
identify a flow. However, what constitutes a flow is locally
determined by the encapsulator. For instance, if the MPLS label
stack contains at least one entropy label and the encapsulator is
capable of reading that entropy label, the entropy label value could
be directly copied to the source port of the UDP header. Otherwise,
the encapsulator may have to perform a hash on the whole label stack
or the five-tuple of the SR-MPLS payload if the payload is determined
as an IP packet. To avoid re-performing the hash or hunting for the
entropy label each time the packet is encapsulated in a UDP tunnel it
MAY be desireable that the entropy value contained in the incoming
packet (i.e., the UDP source port value) is retained when stripping
the UDP header and is re-used as the entropy value of the outgoing
packet.
5. Forwarding Details of SR-MPLS over UDP
This section provides supplementary details to the description found
in Section 4.
[RFC7510] specifies an IP-based encapsulation for MPLS, i.e., MPLS-
in-UDP, which is applicable in some circumstances where IP-based
encapsulation for MPLS is required and further fine-grained load
balancing of MPLS packets over IP networks over Equal-Cost Multipath
(ECMP) and/or Link Aggregation Groups (LAGs) is required as well.
This section provides details about the forwarding procedure when
when UDP encapsulation is adopted for SR-MPLS over IP.
Nodes that are SR capable can process SR-MPLS packets. Not all of
the nodes in an SR domain are SR capable. Some nodes may be "legacy
routers" that cannot handle SR packets but can forward IP packets.
An SR capable node may advertise its capabilities using the IGP as
described in Section 4. There are six types of node in an SR domain:
o Domain ingress nodes that receive packets and encapsulate them for
transmission across the domain. Those packets may be any payload
protocol including native IP packets or packets that are already
MPLS encapsulated.
o Legacy transit nodes that are IP routers but that are not SR
capable (i.e., are not able to perform segment routing).
o Transit nodes that are SR capable but that are not identified by a
SID in the SID stack.
o Transit nodes that are SR capable and need to perform SR routing
because they are identified by a SID in the SID stack.
o The penultimate SR capable node on the path that processes the
last SID on the stack on behalf of the domain egress node.
o The domain egress node that forwards the payload packet for
ultimate delivery.
The following sub-sections describe the processing behavior in each
case.
5.1. Domain Ingress Nodes
Domain ingress nodes receive packets from outside the domain and
encapsulate them to be forwarded across the domain. Received packets
may already be SR-MPLS packets (in the case of connecting two SR-MPLS
networks across a native IP network), or may be native IP or MPLS
packets.
In the latter case, the packet is classified by the domain ingress
node and an SR-MPLS stack is imposed. In the former case the SR-MPLS
stack is already in the packet. The top entry in the stack is popped
from the stack and retained for use below.
The packet is then encapsulated in UDP with the destination port set
to 6635 to indicate "MPLS-UDP" or to 6636 to indicate "MPLS-UDP-DTLS"
as described in [RFC7510]. The source UDP port is set randomly or to
provide entropy as described in [RFC7510] and Section 4.2.3, above.
The packet is then encapsulated in IP for transmission across the
network. The IP source address is set to the domain ingress node,
and the destination address is set to the address corresponding to
the label that was previously popped from the stack.
This processing is equivalent to sending the packet out of a virtual
interface that corresponds to a virtual link between the ingress node
and the next hop SR node realized by a UDP tunnel. The packet is
then sent into the IP network and is routed according to the local
FIB and applying hashing to resolve any ECMP choices.
5.2. Legacy Transit Nodes
A legacy transit node is an IP router that has no SR capabilities.
When such a router receives an SR-MPLS-in-UDP packet it will carry
out normal TTL processing and if the packet is still live it will
forward it as it would any other UDP-in-IP packet. The packet will
be routed toward the destination indicated in the packet header using
the local FIB and applying hashing to resolve any ECMP choices.
If the packet is mistakenly addressed to the legacy router, the UDP
tunnel will be terminated and the packet will be discarded either
because the MPLS-in-UDP port is not supported or because the
uncovered top label has not been allocated. This is, however, a
misconnection and should not occur unless there is a routing error.
5.3. On-Path Pass-Through SR Nodes
Just because a node is SR capable and receives an SR-MPLS-in-UDP
packet does not mean that it performs SR processing on the packet.
Only routers identified by SIDs in the SR stack need to do such
processing.
Routers that are not addressed by the destination address in the IP
header simply treat the packet as a normal UDP-in-IP packet carrying
out normal TTL processing and if the packet is still live routing the
packet according to the local FIB and applying hashing to resolve any
ECMP choices.
This is important because it means that the SR stack can be kept
relatively small and the packet can be steered through the network
using shortest path first routing between selected SR nodes.
5.4. SR Transit Nodes
An SR capable node that is addressed by the top most SID in the stack
when that is not the last SID in the stack (i.e., the S bit is not
set) is an SR transit node. When an SR transit node receives an SR-
MPLS-in-UDP packet that is addressed to it, it acts as follows.
o Perform TTL processing as normal for an IP packet.
o Determine that the packet is addressed to the local node.
o Find that the payload is UDP and that the destination port
indicates MPLS-in-UDP.
o Strip the IP and UDP headers.
o Examine the label at the top of the stack and process according to
the FIB entry (see Section 4.1.
* If the top label identifies this node then no PHP was used on
the incoming segment and the label is popped. Continue the
processing with the new top label.
* Retain the value of the top label.
* If the top label was advertised requesting PHP, pop the label.
(Note that the case where this is the last label in the stack
is covered in Section 5.5.)
o Encapsulate the packet in UDP with the destination port set to
6635 (or 6636 for DTLS) and the source port set for entropy. The
entropy value SHOULD be retained from the received UDP header or
MAY be freshly generated since this is a new UDP tunnel (see
Section 4.2.3).
o Encapsulate the packet in IP with the IP source address set to
this transit router, and the destination address set to the
address corresponding to the SID for the label value retained
earlier.
o Send the packet into the IP network routing the packet according
to the local FIB and applying hashing to resolve any ECMP choices.
5.5. Penultimate SR Transit Nodes
The penultimate SR transit node is an SR transit node as described in
Section 5.4 where the top label is the last label on the stack. When
a penultimate SR transit node receives an SR-MPLS-in-UDP packet that
is addressed to it, it processes as for any other transit node (see
Section 5.4) except for a special case if PHP is supported for the
final SID.
If PHP is allowed for the final SID the penultimate SR transit node
acts as follows:
o Perform TTL processing as normal for an IP packet.
o Determine that the packet is addressed to the local node.
o Find that the payload is UDP and that the destination port
indicates MPLS-in-UDP.
o Strip the IP and UDP headers.
o Examine the label at the top of the stack and process according to
the FIB entry (see Section 4.1.
* If the top label identifies this node then no PHP was used on
the incoming segment and the label is popped. Continue the
processing with the new top label.
* Retain the value of the top label.
* If the top label was advertised requesting PHP, pop the label.
This will have been the last label in the stack. Push an
explicit null label [RFC3032] (0 for IPv4 and 2 for IPv6) with
bottom of stack (S bit) set.
o Encapsulate the packet in UDP with the destination port set to
6635 (or 6636 for DTLS) and the source port set for entropy. The
entropy value SHOULD be retained from the received UDP header or
MAY be freshly generated since this is a new UDP tunnel.
o Encapsulate the packet in IP with the IP source address set to
this transit router, and the destination address set to the domain
egress node IP address corresponding to the SID for the label
value retained earlier.
o Send the packet into the IP network routing the packet according
to the local FIB and applying hashing to resolve any ECMP choices.
5.5.1. A Note on Segment Routing Paths and Penultimate Hop Popping
End-to-end SR paths are comprised of multiple segments. The end When to use IP-based Tunnel: The description in the previous two
point of each segment is identified by a SID in the SID stack. In sections is based on the assumption that MPLS-over-UDP tunnel is
normal SR processing a penultimate hop is the router that performs SR used when the nexthop towards the next segment is not MPLS-
routing immediately prior to the end-of-segment router. PHP applies enabled. However, even in the case where the nexthop towards the
at the penultimate router in a segment. next segment is MPLS-capable, an MPLS-over-UDP tunnel towards the
next segment could still be used instead due to local policies.
For instance, in the example as described in Figure 4, assume F is
now an SR-MPLS-capable transit node while all the other
assumptions keep unchanged, since F is not identified by a SID in
the stack and an MPLS-over-UDP tunnel is preferred to an MPLS LSP
according to local policies, router E would replace the current
top label with an MPLS-over-UDP tunnel toward router G and send it
out.
With SR-MPLS-in-UDP encapsulation, each SR segment is achieved using IP Header Fields: When encapsulating an MPLS packet in UDP, the
an MPLS-in-UDP tunnel that runs the full length of the segment. The resulting packet is further encapsulated in IP for transmission.
SR SID stack on a packet is only examined at the head and tail ends IPv4 or IPv6 may be used according to the capabilities of the
of this segment. Thus, each segment is effectively one hop long in network. The address fields are set as described in Section 3.
the SR overlay network and if there is any PHP processing it takes The other IP header fields (such as DSCP code point, or IPv6 Flow
place at the head-end of the segment. Label) on each UDP-encapsulated segment can be set according to
the operator's policy: they may be copied from the header of the
incoming packet; they may be promoted from the header of the
payload packet; they may be set according to instructions
programmed to be associated with the SID; or they may be
configured dependent on the outgoing interface and payload.
5.6. Domain Egress Nodes Entropy and ECMP: When encapsulating an MPLS packet with an IP
tunnel header that is capable of encoding entropy (such as
[RFC7510]), the corresponding entropy field (the source port in
case UDP tunnel) MAY be filled with an entropy value that is
generated by the encapsulator to uniquely identify a flow.
However, what constitutes a flow is locally determined by the
encapsulator. For instance, if the MPLS label stack contains at
least one entropy label and the encapsulator is capable of reading
that entropy label, the entropy label value could be directly
copied to the source port of the UDP header. Otherwise, the
encapsulator may have to perform a hash on the whole label stack
or the five-tuple of the SR-MPLS payload if the payload is
determined as an IP packet. To avoid re-performing the hash or
hunting for the entropy label each time the packet is encapsulated
in a UDP tunnel it MAY be desirable that the entropy value
contained in the incoming packet (i.e., the UDP source port value)
is retained when stripping the UDP header and is re-used as the
entropy value of the outgoing packet.
The domain egress acts as follows: 5. IANA Considerations
o Perform TTL processing as normal for an IP packet. This document makes no requests for IANA action.
o Determine that the packet is addressed to the local node. 6. Security Considerations
o Find that the payload is UDP and that the destination port The security consideration of [RFC8354] and [RFC7510] apply. DTLS
indicates MPLS-in-UDP. [RFC6347] SHOULD be used where security is needed on an MPLS-SR-over-
UDP segment.
o Strip the IP and UDP headers. It is difficult for an attacker to pass a raw MPLS encoded packet
into a network and operators have considerable experience at
excluding such packets at the network boundaries.
o Examine the label at the top of the stack and process according to It is easy for an ingress node to detect any attempt to smuggle an IP
the FIB entry (see Section 4.1. packet into the network since it would see that the UDP destination
port was set to MPLS. SR packets not having a destination address
terminating in the network would be transparently carried and would
pose no security risk to the network under consideration.
* If the top label identifies this node then no PHP was used on Where control plane techniques are used (as described in
the incoming segment and the label is popped. Continue the Authors' Addresses it is important that these protocols are
processing with the new top label. adequately secured for the environment in which they are run.
* If there is another label it should be the explicit null. Pop 7. Contributors
it but retain its value.
o Forward the payload packet according to its type (as potentially Ahmed Bashandy
indicated by the value of the popped explicit null label) and the Individual
local routing/forwarding mechanisms. Email: abashandy.ietf@gmail.com
6. Contributors
Clarence Filsfils Clarence Filsfils
Cisco Cisco
Email: cfilsfil@cisco.com Email: cfilsfil@cisco.com
John Drake John Drake
Juniper Juniper
Email: jdrake@juniper.net Email: jdrake@juniper.net
Shaowen Ma Shaowen Ma
Juniper Juniper
skipping to change at page 17, line 5 skipping to change at page 13, line 30
Email: gunter.van_de_velde@nokia.com Email: gunter.van_de_velde@nokia.com
Tal Mizrahi Tal Mizrahi
Marvell Marvell
Email: talmi@marvell.com Email: talmi@marvell.com
Jeff Tantsura Jeff Tantsura
Individual Individual
Email: jefftant@gmail.com Email: jefftant@gmail.com
7. Acknowledgements 8. Acknowledgements
Thanks to Joel Halpern, Bruno Decraene, Loa Andersson, Ron Bonica, Thanks to Joel Halpern, Bruno Decraene, Loa Andersson, Ron Bonica,
Eric Rosen, Jim Guichard, and Gunter Van De Velde for their Eric Rosen, Jim Guichard, and Gunter Van De Velde for their
insightful comments on this draft. insightful comments on this draft.
8. IANA Considerations 9. References
No IANA action is required.
9. Security Considerations
TBD.
10. References
10.1. Normative References 9.1. Normative References
[I-D.ietf-isis-encapsulation-cap] [I-D.ietf-isis-encapsulation-cap]
Xu, X., Decraene, B., Raszuk, R., Chunduri, U., Contreras, Xu, X., Decraene, B., Raszuk, R., Chunduri, U., Contreras,
L., and L. Jalil, "Advertising Tunnelling Capability in L., and L. Jalil, "Advertising Tunnelling Capability in
IS-IS", draft-ietf-isis-encapsulation-cap-01 (work in IS-IS", draft-ietf-isis-encapsulation-cap-01 (work in
progress), April 2017. progress), April 2017.
[I-D.ietf-isis-segment-routing-extensions] [I-D.ietf-isis-segment-routing-extensions]
Previdi, S., Ginsberg, L., Filsfils, C., Bashandy, A., Previdi, S., Ginsberg, L., Filsfils, C., Bashandy, A.,
Gredler, H., Litkowski, S., Decraene, B., and J. Tantsura, Gredler, H., Litkowski, S., Decraene, B., and J. Tantsura,
"IS-IS Extensions for Segment Routing", draft-ietf-isis- "IS-IS Extensions for Segment Routing", draft-ietf-isis-
segment-routing-extensions-15 (work in progress), December segment-routing-extensions-16 (work in progress), April
2017. 2018.
[I-D.ietf-ospf-encapsulation-cap] [I-D.ietf-ospf-encapsulation-cap]
Xu, X., Decraene, B., Raszuk, R., Contreras, L., and L. Xu, X., Decraene, B., Raszuk, R., Contreras, L., and L.
Jalil, "The Tunnel Encapsulations OSPF Router Jalil, "The Tunnel Encapsulations OSPF Router
Information", draft-ietf-ospf-encapsulation-cap-09 (work Information", draft-ietf-ospf-encapsulation-cap-09 (work
in progress), October 2017. in progress), October 2017.
[I-D.ietf-ospf-segment-routing-extensions] [I-D.ietf-ospf-segment-routing-extensions]
Psenak, P., Previdi, S., Filsfils, C., Gredler, H., Psenak, P., Previdi, S., Filsfils, C., Gredler, H.,
Shakir, R., Henderickx, W., and J. Tantsura, "OSPF Shakir, R., Henderickx, W., and J. Tantsura, "OSPF
Extensions for Segment Routing", draft-ietf-ospf-segment- Extensions for Segment Routing", draft-ietf-ospf-segment-
routing-extensions-24 (work in progress), December 2017. routing-extensions-25 (work in progress), April 2018.
[I-D.ietf-spring-segment-routing-mpls] [I-D.ietf-spring-segment-routing-mpls]
Bashandy, A., Filsfils, C., Previdi, S., Decraene, B., Bashandy, A., Filsfils, C., Previdi, S., Decraene, B.,
Litkowski, S., and R. Shakir, "Segment Routing with MPLS Litkowski, S., and R. Shakir, "Segment Routing with MPLS
data plane", draft-ietf-spring-segment-routing-mpls-12 data plane", draft-ietf-spring-segment-routing-mpls-13
(work in progress), February 2018. (work in progress), April 2018.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997, DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>. <https://www.rfc-editor.org/info/rfc2119>.
[RFC3031] Rosen, E., Viswanathan, A., and R. Callon, "Multiprotocol [RFC3031] Rosen, E., Viswanathan, A., and R. Callon, "Multiprotocol
Label Switching Architecture", RFC 3031, Label Switching Architecture", RFC 3031,
DOI 10.17487/RFC3031, January 2001, DOI 10.17487/RFC3031, January 2001,
<https://www.rfc-editor.org/info/rfc3031>. <https://www.rfc-editor.org/info/rfc3031>.
[RFC3032] Rosen, E., Tappan, D., Fedorkow, G., Rekhter, Y., [RFC3032] Rosen, E., Tappan, D., Fedorkow, G., Rekhter, Y.,
Farinacci, D., Li, T., and A. Conta, "MPLS Label Stack Farinacci, D., Li, T., and A. Conta, "MPLS Label Stack
Encoding", RFC 3032, DOI 10.17487/RFC3032, January 2001, Encoding", RFC 3032, DOI 10.17487/RFC3032, January 2001,
<https://www.rfc-editor.org/info/rfc3032>. <https://www.rfc-editor.org/info/rfc3032>.
[RFC6347] Rescorla, E. and N. Modadugu, "Datagram Transport Layer
Security Version 1.2", RFC 6347, DOI 10.17487/RFC6347,
January 2012, <https://www.rfc-editor.org/info/rfc6347>.
[RFC7510] Xu, X., Sheth, N., Yong, L., Callon, R., and D. Black, [RFC7510] Xu, X., Sheth, N., Yong, L., Callon, R., and D. Black,
"Encapsulating MPLS in UDP", RFC 7510, "Encapsulating MPLS in UDP", RFC 7510,
DOI 10.17487/RFC7510, April 2015, DOI 10.17487/RFC7510, April 2015,
<https://www.rfc-editor.org/info/rfc7510>. <https://www.rfc-editor.org/info/rfc7510>.
[RFC7684] Psenak, P., Gredler, H., Shakir, R., Henderickx, W., [RFC7684] Psenak, P., Gredler, H., Shakir, R., Henderickx, W.,
Tantsura, J., and A. Lindem, "OSPFv2 Prefix/Link Attribute Tantsura, J., and A. Lindem, "OSPFv2 Prefix/Link Attribute
Advertisement", RFC 7684, DOI 10.17487/RFC7684, November Advertisement", RFC 7684, DOI 10.17487/RFC7684, November
2015, <https://www.rfc-editor.org/info/rfc7684>. 2015, <https://www.rfc-editor.org/info/rfc7684>.
skipping to change at page 18, line 44 skipping to change at page 15, line 24
[RFC7981] Ginsberg, L., Previdi, S., and M. Chen, "IS-IS Extensions [RFC7981] Ginsberg, L., Previdi, S., and M. Chen, "IS-IS Extensions
for Advertising Router Information", RFC 7981, for Advertising Router Information", RFC 7981,
DOI 10.17487/RFC7981, October 2016, DOI 10.17487/RFC7981, October 2016,
<https://www.rfc-editor.org/info/rfc7981>. <https://www.rfc-editor.org/info/rfc7981>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>. May 2017, <https://www.rfc-editor.org/info/rfc8174>.
10.2. Informative References 9.2. Informative References
[I-D.ietf-6man-segment-routing-header] [I-D.ietf-6man-segment-routing-header]
Previdi, S., Filsfils, C., Raza, K., Dukes, D., Leddy, J., Previdi, S., Filsfils, C., Leddy, J., Matsushima, S., and
Field, B., daniel.voyer@bell.ca, d., d. daniel.voyer@bell.ca, "IPv6 Segment Routing Header
daniel.bernier@bell.ca, d., Matsushima, S., Leung, I., (SRH)", draft-ietf-6man-segment-routing-header-13 (work in
Linkova, J., Aries, E., Kosugi, T., Vyncke, E., Lebrun, progress), May 2018.
D., Steinberg, D., and R. Raszuk, "IPv6 Segment Routing
Header (SRH)", draft-ietf-6man-segment-routing-header-08
(work in progress), January 2018.
[I-D.ietf-mpls-spring-entropy-label] [I-D.ietf-mpls-spring-entropy-label]
Kini, S., Kompella, K., Sivabalan, S., Litkowski, S., Kini, S., Kompella, K., Sivabalan, S., Litkowski, S.,
Shakir, R., and J. Tantsura, "Entropy label for SPRING Shakir, R., and J. Tantsura, "Entropy label for SPRING
tunnels", draft-ietf-mpls-spring-entropy-label-08 (work in tunnels", draft-ietf-mpls-spring-entropy-label-11 (work in
progress), January 2018. progress), May 2018.
[RFC8354] Brzozowski, J., Leddy, J., Filsfils, C., Maglione, R.,
Ed., and M. Townsley, "Use Cases for IPv6 Source Packet
Routing in Networking (SPRING)", RFC 8354,
DOI 10.17487/RFC8354, March 2018,
<https://www.rfc-editor.org/info/rfc8354>.
Authors' Addresses Authors' Addresses
Xiaohu Xu Xiaohu Xu
Alibaba Alibaba
Email: xiaohu.xxh@alibaba-inc.com Email: xiaohu.xxh@alibaba-inc.com
Stewart Bryant Stewart Bryant
Huawei Huawei
Email: stewart.bryant@gmail.com Email: stewart.bryant@gmail.com
Adrian Farrel Adrian Farrel
Juniper Juniper
Email: afarrel@juniper.net Email: afarrel@juniper.net
skipping to change at page 19, line 37 skipping to change at page 16, line 14
Stewart Bryant Stewart Bryant
Huawei Huawei
Email: stewart.bryant@gmail.com Email: stewart.bryant@gmail.com
Adrian Farrel Adrian Farrel
Juniper Juniper
Email: afarrel@juniper.net Email: afarrel@juniper.net
Ahmed Bashandy Syed Hassan
Cisco Cisco
Email: bashandy@cisco.com Email: shassan@cisco.com
Wim Henderickx Wim Henderickx
Nokia Nokia
Email: wim.henderickx@nokia.com Email: wim.henderickx@nokia.com
Zhenbin Li Zhenbin Li
Huawei Huawei
Email: lizhenbin@huawei.com Email: lizhenbin@huawei.com
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