draft-ietf-detnet-mpls-09.txt | draft-ietf-detnet-mpls-10.txt | |||
---|---|---|---|---|
DetNet B. Varga, Ed. | DetNet B. Varga, Ed. | |||
Internet-Draft J. Farkas | Internet-Draft J. Farkas | |||
Intended status: Standards Track Ericsson | Intended status: Standards Track Ericsson | |||
Expires: January 13, 2021 L. Berger | Expires: January 27, 2021 L. Berger | |||
LabN Consulting, L.L.C. | LabN Consulting, L.L.C. | |||
A. Malis | A. Malis | |||
Malis Consulting | Malis Consulting | |||
S. Bryant | S. Bryant | |||
Futurewei Technologies | Futurewei Technologies | |||
J. Korhonen | J. Korhonen | |||
July 12, 2020 | July 26, 2020 | |||
DetNet Data Plane: MPLS | DetNet Data Plane: MPLS | |||
draft-ietf-detnet-mpls-09 | draft-ietf-detnet-mpls-10 | |||
Abstract | Abstract | |||
This document specifies the Deterministic Networking data plane when | This document specifies the Deterministic Networking data plane when | |||
operating over an MPLS Packet Switched Networks. | operating over an MPLS Packet Switched Network. It leverages | |||
existing pseudowire (PW) encapsulations and MPLS Traffic Engineering | ||||
encapsulations and mechanisms. This document builds on the DetNet | ||||
Architecture and Data Plane Framework. | ||||
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 | |||
Task Force (IETF). Note that other groups may also distribute | Task Force (IETF). Note that other groups may also distribute | |||
working documents as Internet-Drafts. The list of current Internet- | working documents as Internet-Drafts. The list of current Internet- | |||
Drafts is at https://datatracker.ietf.org/drafts/current/. | Drafts is at https://datatracker.ietf.org/drafts/current/. | |||
Internet-Drafts are draft documents valid for a maximum of six months | Internet-Drafts are draft documents valid for a maximum of six months | |||
and may be updated, replaced, or obsoleted by other documents at any | and may be updated, replaced, or obsoleted by other documents at any | |||
time. It is inappropriate to use Internet-Drafts as reference | time. It is inappropriate to use Internet-Drafts as reference | |||
material or to cite them other than as "work in progress." | material or to cite them other than as "work in progress." | |||
This Internet-Draft will expire on January 13, 2021. | This Internet-Draft will expire on January 27, 2021. | |||
Copyright Notice | Copyright Notice | |||
Copyright (c) 2020 IETF Trust and the persons identified as the | Copyright (c) 2020 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 | |||
Provisions Relating to IETF Documents | Provisions Relating to IETF Documents | |||
(https://trustee.ietf.org/license-info) in effect on the date of | (https://trustee.ietf.org/license-info) in effect on the date of | |||
publication of this document. Please review these documents | publication of this document. Please review these documents | |||
skipping to change at page 2, line 31 ¶ | skipping to change at page 2, line 34 ¶ | |||
4.2. MPLS Data Plane Encapsulation . . . . . . . . . . . . . . 9 | 4.2. MPLS Data Plane Encapsulation . . . . . . . . . . . . . . 9 | |||
4.2.1. DetNet Control Word and the DetNet Sequence Number . 10 | 4.2.1. DetNet Control Word and the DetNet Sequence Number . 10 | |||
4.2.2. S-Labels . . . . . . . . . . . . . . . . . . . . . . 11 | 4.2.2. S-Labels . . . . . . . . . . . . . . . . . . . . . . 11 | |||
4.2.3. F-Labels . . . . . . . . . . . . . . . . . . . . . . 14 | 4.2.3. F-Labels . . . . . . . . . . . . . . . . . . . . . . 14 | |||
4.3. OAM Indication . . . . . . . . . . . . . . . . . . . . . 17 | 4.3. OAM Indication . . . . . . . . . . . . . . . . . . . . . 17 | |||
4.4. Flow Aggregation . . . . . . . . . . . . . . . . . . . . 17 | 4.4. Flow Aggregation . . . . . . . . . . . . . . . . . . . . 17 | |||
4.4.1. Aggregation Via LSP Hierarchy . . . . . . . . . . . . 17 | 4.4.1. Aggregation Via LSP Hierarchy . . . . . . . . . . . . 17 | |||
4.4.2. Aggregating DetNet Flows as a new DetNet flow . . . . 18 | 4.4.2. Aggregating DetNet Flows as a new DetNet flow . . . . 18 | |||
4.5. Service Sub-Layer Considerations . . . . . . . . . . . . 19 | 4.5. Service Sub-Layer Considerations . . . . . . . . . . . . 19 | |||
4.5.1. Edge Node Processing . . . . . . . . . . . . . . . . 19 | 4.5.1. Edge Node Processing . . . . . . . . . . . . . . . . 19 | |||
4.5.2. Relay Node Processing . . . . . . . . . . . . . . . . 19 | 4.5.2. Relay Node Processing . . . . . . . . . . . . . . . . 20 | |||
4.6. Forwarding Sub-Layer Considerations . . . . . . . . . . . 20 | 4.6. Forwarding Sub-Layer Considerations . . . . . . . . . . . 20 | |||
4.6.1. Class of Service . . . . . . . . . . . . . . . . . . 20 | 4.6.1. Class of Service . . . . . . . . . . . . . . . . . . 20 | |||
4.6.2. Quality of Service . . . . . . . . . . . . . . . . . 21 | 4.6.2. Quality of Service . . . . . . . . . . . . . . . . . 21 | |||
5. Management and Control Information Summary . . . . . . . . . 21 | 5. Management and Control Information Summary . . . . . . . . . 21 | |||
5.1. Service Sub-Layer Information Summary . . . . . . . . . . 22 | 5.1. Service Sub-Layer Information Summary . . . . . . . . . . 22 | |||
5.1.1. Service Aggregation Information Summary . . . . . . . 23 | 5.1.1. Service Aggregation Information Summary . . . . . . . 23 | |||
5.2. Forwarding Sub-Layer Information Summary . . . . . . . . 23 | 5.2. Forwarding Sub-Layer Information Summary . . . . . . . . 23 | |||
6. Security Considerations . . . . . . . . . . . . . . . . . . . 24 | 6. Security Considerations . . . . . . . . . . . . . . . . . . . 24 | |||
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 25 | 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 25 | |||
8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 25 | 8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 25 | |||
9. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 25 | 9. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 26 | |||
10. References . . . . . . . . . . . . . . . . . . . . . . . . . 25 | 10. References . . . . . . . . . . . . . . . . . . . . . . . . . 26 | |||
10.1. Normative References . . . . . . . . . . . . . . . . . . 25 | 10.1. Normative References . . . . . . . . . . . . . . . . . . 26 | |||
10.2. Informative References . . . . . . . . . . . . . . . . . 27 | 10.2. Informative References . . . . . . . . . . . . . . . . . 28 | |||
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 30 | Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 30 | |||
1. Introduction | 1. Introduction | |||
Deterministic Networking (DetNet) is a service that can be offered by | Deterministic Networking (DetNet) is a service that can be offered by | |||
a network to DetNet flows. DetNet provides these flows extremely low | a network to DetNet flows. DetNet provides these flows with | |||
packet loss rates and assured maximum end-to-end delivery latency. | extremely low packet loss rates and assured maximum end-to-end | |||
General background and concepts of DetNet can be found in [RFC8655]. | delivery latency. General background and concepts of DetNet can be | |||
found in [RFC8655]. | ||||
The DetNet Architecture models the DetNet related data plane | The DetNet Architecture models the DetNet related data plane | |||
functions decomposed into two sub-layers: a service sub-layer and a | functions decomposed into two sub-layers: a service sub-layer and a | |||
forwarding sub-layer. The service sub-layer is used to provide | forwarding sub-layer. The service sub-layer is used to provide | |||
DetNet service functions such as protection and reordering. The | DetNet service functions such as protection and reordering. The | |||
forwarding sub-layer is used to provide forwarding assurance (low | forwarding sub-layer is used to provide forwarding assurance (low | |||
loss, assured latency, and limited reordering). | loss, assured latency, and limited reordering). | |||
This document specifies the DetNet data plane operation and the on- | This document specifies the DetNet data plane operation and the on- | |||
wire encapsulation of DetNet flows over an MPLS-based Packet Switched | wire encapsulation of DetNet flows over an MPLS-based Packet Switched | |||
Network (PSN) using the service sub-layer reference model. MPLS | Network (PSN) using the service reference model. MPLS encapsulation | |||
encapsulation already provides a solid foundation of building blocks | already provides a solid foundation of building blocks to enable the | |||
to enable the DetNet service and forwarding sub-layer functions. | DetNet service and forwarding sub-layer functions. MPLS encapsulated | |||
MPLS encapsulated DetNet can be carried over a variety of different | DetNet can be carried over a variety of different network | |||
network technologies that can provide the DetNet required level of | technologies that can provide the DetNet required level of service. | |||
service. However, the specific details of how DetNet MPLS is carried | However, the specific details of how DetNet MPLS is carried over | |||
over different network technologies is out of scope of this document. | different network technologies is out of scope of this document. | |||
MPLS encapsulated DetNet flows can carry different types of traffic. | MPLS encapsulated DetNet flows can carry different types of traffic. | |||
The details of the types of traffic that are carried in DetNet are | The details of the types of traffic that are carried in DetNet are | |||
also out of scope of this document. An example of IP using DetNet | also out of scope of this document. An example of IP using DetNet | |||
MPLS sub-networks can be found in [I-D.ietf-detnet-ip]. DetNet MPLS | MPLS sub-networks can be found in [I-D.ietf-detnet-ip]. DetNet MPLS | |||
may use an associated controller and Operations, Administration, and | may use an associated controller and Operations, Administration, and | |||
Maintenance (OAM) functions that are defined outside of this | Maintenance (OAM) functions that are defined outside of this | |||
document. | document. | |||
Background information common to all data planes for DetNet can be | Background information common to all data planes for DetNet can be | |||
skipping to change at page 8, line 38 ¶ | skipping to change at page 8, line 38 ¶ | |||
Figure 3: MPLS-Based Native DetNet | Figure 3: MPLS-Based Native DetNet | |||
4. MPLS-Based DetNet Data Plane Solution | 4. MPLS-Based DetNet Data Plane Solution | |||
4.1. DetNet Over MPLS Encapsulation Components | 4.1. DetNet Over MPLS Encapsulation Components | |||
To carry DetNet over MPLS the following is required: | To carry DetNet over MPLS the following is required: | |||
1. A method of identifying the MPLS payload type. | 1. A method of identifying the MPLS payload type. | |||
2. A method of identifying the DetNet flow group to the processing | 2. A method of identifying the DetNet flow(s) to the processing | |||
element. | element. | |||
3. A method of distinguishing DetNet OAM packets from DetNet data | 3. A method of distinguishing DetNet OAM packets from DetNet data | |||
packets. | packets. | |||
4. A method of carrying the DetNet sequence number. | 4. A method of carrying the DetNet sequence number. | |||
5. A suitable LSP to deliver the packet to the egress PE. | 5. A suitable LSP to deliver the packet to the egress PE. | |||
6. A method of carrying queuing and forwarding indication. | 6. A method of carrying queuing and forwarding indication. | |||
skipping to change at page 9, line 29 ¶ | skipping to change at page 9, line 29 ¶ | |||
required queue processing as well as the forwarding parameters. Note | required queue processing as well as the forwarding parameters. Note | |||
that the possible use of Penultimate Hop Popping (PHP) means that the | that the possible use of Penultimate Hop Popping (PHP) means that the | |||
S-Label may be the only label received at the terminating DetNet | S-Label may be the only label received at the terminating DetNet | |||
service. | service. | |||
4.2. MPLS Data Plane Encapsulation | 4.2. MPLS Data Plane Encapsulation | |||
Figure 4 illustrates a DetNet data plane MPLS encapsulation. The | Figure 4 illustrates a DetNet data plane MPLS encapsulation. The | |||
MPLS-based encapsulation of the DetNet flows is well suited for the | MPLS-based encapsulation of the DetNet flows is well suited for the | |||
scenarios described in [I-D.ietf-detnet-data-plane-framework]. | scenarios described in [I-D.ietf-detnet-data-plane-framework]. | |||
Furthermore, an end to end DetNet service i.e., native DetNet | Furthermore, an end-to-end DetNet service i.e., native DetNet | |||
deployment (see Section 3.2) is also possible if DetNet end systems | deployment (see Section 3.2) is also possible if DetNet end systems | |||
are capable of initiating and termination MPLS encapsulated packets. | are capable of initiating and termination MPLS encapsulated packets. | |||
The MPLS-based DetNet data plane encapsulation consists of: | The MPLS-based DetNet data plane encapsulation consists of: | |||
o DetNet control word (d-CW) containing sequencing information for | o DetNet control word (d-CW) containing sequencing information for | |||
packet replication and duplicate elimination purposes, and the OAM | packet replication and duplicate elimination purposes, and the OAM | |||
indicator. | indicator. | |||
o DetNet service Label (S-Label) that identifies a DetNet flow at | o DetNet service Label (S-Label) that identifies a DetNet flow at | |||
skipping to change at page 16, line 27 ¶ | skipping to change at page 16, line 27 ¶ | |||
Resources may be allocated in a hierarchical fashion per LSP that is | Resources may be allocated in a hierarchical fashion per LSP that is | |||
represented by each F-Label. Each LSP MAY be provisioned with a | represented by each F-Label. Each LSP MAY be provisioned with a | |||
service parameters that dictates the specific traffic treatment to be | service parameters that dictates the specific traffic treatment to be | |||
received by the traffic carried over that LSP. Implementations of | received by the traffic carried over that LSP. Implementations of | |||
this document MUST ensure that traffic carried over each LSP | this document MUST ensure that traffic carried over each LSP | |||
represented by one or more F-Labels receives the traffic treatment | represented by one or more F-Labels receives the traffic treatment | |||
provisioned for that LSP. Typical mechanisms used to provide | provisioned for that LSP. Typical mechanisms used to provide | |||
different treatment to different flows includes the allocation of | different treatment to different flows includes the allocation of | |||
system resources (such as queues and buffers) and provisioning or | system resources (such as queues and buffers) and provisioning or | |||
related parameters (such as shaping, and policing). Support can also | related parameters (such as shaping, and policing) that may be found | |||
be provided via an underlying network technology such IEEE802.1 TSN | in implementations of Resource ReSerVation Protocol (RSVP) [RFC2205] | |||
[I-D.ietf-detnet-mpls-over-tsn]. The specific mechanisms used by a | (RSVP) and RSVP-TE [RFC3209] and [RFC3473]. Support can also be | |||
DetNet node to ensure DetNet service delivery requirements are met | provided via an underlying network technology such IEEE802.1 TSN | |||
[I-D.ietf-detnet-mpls-over-tsn]. The specific mechanisms selected by | ||||
a DetNet node to ensure DetNet service delivery requirements are met | ||||
for supported DetNet flows is outside the scope of this document. | for supported DetNet flows is outside the scope of this document. | |||
Packets that are marked in a way that do not correspond to allocated | Packets that are marked in a way that do not correspond to allocated | |||
resources, e.g., lack a provisioned F-Label, can disrupt the QoS | resources, e.g., lack a provisioned F-Label, can disrupt the QoS | |||
offered to properly reserved DetNet flows by using resources | offered to properly reserved DetNet flows by using resources | |||
allocated to the reserved flows. Therefore, the network nodes of a | allocated to the reserved flows. Therefore, the network nodes of a | |||
DetNet network: | DetNet network: | |||
o MUST defend the DetNet QoS by discarding or remarking (to an | o MUST defend the DetNet QoS by discarding or remarking (to an | |||
allocated DetNet flow or non-competing non-DetNet flow) packets | allocated DetNet flow or non-competing non-DetNet flow) packets | |||
skipping to change at page 22, line 10 ¶ | skipping to change at page 22, line 16 ¶ | |||
Much like other MPLS labels, there are a number of alternatives | Much like other MPLS labels, there are a number of alternatives | |||
available for DetNet S-Label and F-Label advertisement to an upstream | available for DetNet S-Label and F-Label advertisement to an upstream | |||
peer node. These include distributed signaling protocols such as | peer node. These include distributed signaling protocols such as | |||
RSVP-TE, centralized label distribution via a controller that manages | RSVP-TE, centralized label distribution via a controller that manages | |||
both the sender and the receiver using NETCONF/YANG, BGP, PCEP, etc., | both the sender and the receiver using NETCONF/YANG, BGP, PCEP, etc., | |||
and hybrid combinations of the two. The details of the controller | and hybrid combinations of the two. The details of the controller | |||
plane solution required for the label distribution and the management | plane solution required for the label distribution and the management | |||
of the label number space are out of scope of this document. There | of the label number space are out of scope of this document. There | |||
are particular DetNet considerations and requirements that are | are particular DetNet considerations and requirements that are | |||
discussed in [I-D.ietf-detnet-data-plane-framework]. | discussed in [I-D.ietf-detnet-data-plane-framework]. Conformance | |||
language is not used in the summary since it applies to future | ||||
mechanisms such as those that may be provided in signaling and YANG | ||||
models, e.g., [I-D.ietf-detnet-yang]. | ||||
5.1. Service Sub-Layer Information Summary | 5.1. Service Sub-Layer Information Summary | |||
The following summarizes the information that is needed on service | The following summarizes the information that is needed on service | |||
sub-layer aware nodes that transmit DetNet MPLS traffic, on a per | sub-layer aware nodes that transmit DetNet MPLS traffic, on a per | |||
service basis: | service basis: | |||
o App-Flow identification information, e.g., IP information as | o App-Flow identification information, e.g., IP information as | |||
defined in [I-D.ietf-detnet-ip-over-mpls]. Note, this information | defined in [I-D.ietf-detnet-ip-over-mpls]. Note, this information | |||
is not needed on DetNet relay nodes. | is not needed on DetNet relay nodes. | |||
skipping to change at page 24, line 29 ¶ | skipping to change at page 24, line 40 ¶ | |||
forwarded as a transit node, or provided to the service sub-layer. | forwarded as a transit node, or provided to the service sub-layer. | |||
It is the responsibility of the DetNet controller plane to properly | It is the responsibility of the DetNet controller plane to properly | |||
provision both flow identification information and the flow specific | provision both flow identification information and the flow specific | |||
resources needed to provided the traffic treatment needed to meet | resources needed to provided the traffic treatment needed to meet | |||
each flow's service requirements. This applies for aggregated and | each flow's service requirements. This applies for aggregated and | |||
individual flows. | individual flows. | |||
6. Security Considerations | 6. Security Considerations | |||
General security considerations are described in [RFC8655]. | Detailed security considerations for DetNet are cataloged in | |||
Additionally, security considerations and a threat analysis are | [I-D.ietf-detnet-security], and more general security considerations | |||
described in [I-D.ietf-detnet-security]. This section considers | are described in [RFC8655]. This section considers exclusively | |||
security considerations which are specific to the DetNet MPLS data | security considerations which are specific to the DetNet MPLS data | |||
plane. The considerations raised related to MPLS networks in general | plane. The considerations raised related to MPLS networks in general | |||
in [RFC5920] are equally applicable to the the DetNet MPLS data | in [RFC5920] are equally applicable to the the DetNet MPLS data | |||
plane. | plane. | |||
Security aspects which are unique to DetNet are those whose aim is to | Security aspects which are unique to DetNet are those whose aim is to | |||
provide the specific quality of service aspects of DetNet, which are | provide the specific quality of service aspects of DetNet, which are | |||
primarily to deliver data flows with extremely low packet loss rates | primarily to deliver data flows with extremely low packet loss rates | |||
and bounded end-to-end delivery latency. | and bounded end-to-end delivery latency. Achieving such loss rates | |||
and bounded latency may not be possible in the face of a highly | ||||
capable adversary, such as the one envisioned by the Internet Threat | ||||
Model of BCP 72 that can arbitrarily drop or delay any or all | ||||
traffic. In order to present meaningful security considerations, we | ||||
consider a somewhat weaker attacker who does not control the physical | ||||
links of the DetNet domain, but may have the ability to control a | ||||
network node within the boundary of the DetNet domain. | ||||
The primary considerations for the data plane is to maintain | The primary consideration for the DetNet data plane is to maintain | |||
integrity of data and delivery of the associated DetNet service | integrity of data and delivery of the associated DetNet service | |||
traversing the DetNet network. Application flows can be protected | traversing the DetNet network. Application flows can be protected | |||
through whatever means is provided by the underlying technology. For | through whatever means are provided by the underlying technology. | |||
example, encryption may be used, such as that provided by IPSec | For example, encryption may be used, such as that provided by IPsec | |||
[RFC4301] for IP flows and/or by an underlying sub-net using MACSec | [RFC4301] for IP flows and/or by an underlying sub-net using MACSec | |||
[IEEE802.1AE-2018] for IP over Ethernet (Layer-2) flows. | [IEEE802.1AE-2018] for IP over Ethernet (Layer-2) flows. | |||
From a data plane perspective this document does not add or modify | From a data plane perspective this document does not add or modify | |||
any header information. | any header information. | |||
At the management and control level DetNet flows are identified on a | At the management and control level DetNet flows are identified on a | |||
per-flow basis, which may provide controller plane attackers with | per-flow basis, which may provide controller plane attackers with | |||
additional information about the data flows (when compared to | additional information about the data flows (when compared to | |||
controller planes that do not include per-flow identification). This | controller planes that do not include per-flow identification). This | |||
skipping to change at page 28, line 21 ¶ | skipping to change at page 28, line 33 ¶ | |||
Varga, B., Farkas, J., Malis, A., and S. Bryant, "DetNet | Varga, B., Farkas, J., Malis, A., and S. Bryant, "DetNet | |||
Data Plane: MPLS over IEEE 802.1 Time Sensitive Networking | Data Plane: MPLS over IEEE 802.1 Time Sensitive Networking | |||
(TSN)", draft-ietf-detnet-mpls-over-tsn-03 (work in | (TSN)", draft-ietf-detnet-mpls-over-tsn-03 (work in | |||
progress), June 2020. | progress), June 2020. | |||
[I-D.ietf-detnet-security] | [I-D.ietf-detnet-security] | |||
Mizrahi, T. and E. Grossman, "Deterministic Networking | Mizrahi, T. and E. Grossman, "Deterministic Networking | |||
(DetNet) Security Considerations", draft-ietf-detnet- | (DetNet) Security Considerations", draft-ietf-detnet- | |||
security-10 (work in progress), May 2020. | security-10 (work in progress), May 2020. | |||
[I-D.ietf-detnet-yang] | ||||
Geng, X., Chen, M., Ryoo, Y., Fedyk, D., Li, Z., and R. | ||||
Rahman, "Deterministic Networking (DetNet) Configuration | ||||
YANG Model", draft-ietf-detnet-yang-07 (work in progress), | ||||
July 2020. | ||||
[IEEE802.1AE-2018] | [IEEE802.1AE-2018] | |||
IEEE Standards Association, "IEEE Std 802.1AE-2018 MAC | IEEE Standards Association, "IEEE Std 802.1AE-2018 MAC | |||
Security (MACsec)", 2018, | Security (MACsec)", 2018, | |||
<https://ieeexplore.ieee.org/document/8585421>. | <https://ieeexplore.ieee.org/document/8585421>. | |||
[RFC2205] Braden, R., Ed., Zhang, L., Berson, S., Herzog, S., and S. | [RFC2205] Braden, R., Ed., Zhang, L., Berson, S., Herzog, S., and S. | |||
Jamin, "Resource ReSerVation Protocol (RSVP) -- Version 1 | Jamin, "Resource ReSerVation Protocol (RSVP) -- Version 1 | |||
Functional Specification", RFC 2205, DOI 10.17487/RFC2205, | Functional Specification", RFC 2205, DOI 10.17487/RFC2205, | |||
September 1997, <https://www.rfc-editor.org/info/rfc2205>. | September 1997, <https://www.rfc-editor.org/info/rfc2205>. | |||
End of changes. 18 change blocks. | ||||
34 lines changed or deleted | 56 lines changed or added | |||
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