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Internet Engineering Task Force (IETF) J. He Request for Comments: 9270 I. Busi Updates: 4872, 4873 Huawei Technologies Category: Standards Track J. Ryoo ISSN: 2070-1721 B. Yoon

                                                                  ETRI
                                                               P. Park
                                                                    KT
                                                           August 2022
       GMPLS Signaling Extensions for Shared Mesh Protection

Abstract

 ITU-T Recommendation G.808.3 defines the generic aspects of a Shared
 Mesh Protection (SMP) mechanism, where the difference between SMP and
 Shared Mesh Restoration (SMR) is also identified.  ITU-T
 Recommendation G.873.3 defines the protection switching operation and
 associated protocol for SMP at the Optical Data Unit (ODU) layer.
 RFC 7412 provides requirements for any mechanism that would be used
 to implement SMP in a Multi-Protocol Label Switching - Transport
 Profile (MPLS-TP) network.
 This document updates RFCs 4872 and 4873 to provide extensions for
 Generalized Multi-Protocol Label Switching (GMPLS) signaling to
 support the control of the SMP mechanism.

Status of This Memo

 This is an Internet Standards Track document.
 This document is a product of the Internet Engineering Task Force
 (IETF).  It represents the consensus of the IETF community.  It has
 received public review and has been approved for publication by the
 Internet Engineering Steering Group (IESG).  Further information on
 Internet Standards is available in Section 2 of RFC 7841.
 Information about the current status of this document, any errata,
 and how to provide feedback on it may be obtained at
 https://www.rfc-editor.org/info/rfc9270.

Copyright Notice

 Copyright (c) 2022 IETF Trust and the persons identified as the
 document authors.  All rights reserved.
 This document is subject to BCP 78 and the IETF Trust's Legal
 Provisions Relating to IETF Documents
 (https://trustee.ietf.org/license-info) in effect on the date of
 publication of this document.  Please review these documents
 carefully, as they describe your rights and restrictions with respect
 to this document.  Code Components extracted from this document must
 include Revised BSD License text as described in Section 4.e of the
 Trust Legal Provisions and are provided without warranty as described
 in the Revised BSD License.
 This document may contain material from IETF Documents or IETF
 Contributions published or made publicly available before November
 10, 2008.  The person(s) controlling the copyright in some of this
 material may not have granted the IETF Trust the right to allow
 modifications of such material outside the IETF Standards Process.
 Without obtaining an adequate license from the person(s) controlling
 the copyright in such materials, this document may not be modified
 outside the IETF Standards Process, and derivative works of it may
 not be created outside the IETF Standards Process, except to format
 it for publication as an RFC or to translate it into languages other
 than English.

Table of Contents

 1.  Introduction
 2.  Conventions Used in This Document
 3.  SMP Definition
 4.  Operation of SMP with GMPLS Signaling Extensions
 5.  GMPLS Signaling Extensions for SMP
   5.1.  Identifiers
   5.2.  Signaling Primary LSPs
   5.3.  Signaling Secondary LSPs
   5.4.  SMP Preemption Priority
   5.5.  Availability of Shared Resources: The Notify Message
   5.6.  SMP APS Configuration
 6.  Updates to PROTECTION Object
   6.1.  New Protection Type
   6.2.  Updates to Definitions of Notification and Operational Bits
   6.3.  Preemption Priority
 7.  IANA Considerations
 8.  Security Considerations
 9.  References
   9.1.  Normative References
   9.2.  Informative References
 Acknowledgements
 Contributors
 Authors' Addresses

1. Introduction

 RFC 4872 [RFC4872] defines extensions for Resource Reservation
 Protocol - Traffic Engineering (RSVP-TE) to support Shared Mesh
 Restoration (SMR) mechanisms.  SMR can be seen as a particular case
 of preplanned Label Switched Path (LSP) rerouting that reduces the
 recovery resource requirements by allowing multiple protecting LSPs
 to share common link and node resources.  The recovery resources for
 the protecting LSPs are pre-reserved during the provisioning phase,
 and explicit restoration signaling is required to activate (i.e.,
 commit resource allocation at the data plane) a specific protecting
 LSP that was instantiated during the provisioning phase.  RFC 4873
 [RFC4873] details the encoding of the last 32-bit Reserved field of
 the PROTECTION object defined in [RFC4872].
 ITU-T Recommendation G.808.3 [G808.3] defines the generic aspects of
 a Shared Mesh Protection (SMP) mechanism, which are not specific to a
 particular network technology in terms of architecture types,
 preemption principle, path monitoring methods, etc.  ITU-T
 Recommendation G.873.3 [G873.3] defines the protection switching
 operation and associated protocol for SMP at the Optical Data Unit
 (ODU) layer.  RFC 7412 [RFC7412] provides requirements for any
 mechanism that would be used to implement SMP in a Multi-Protocol
 Label Switching - Transport Profile (MPLS-TP) network.
 SMP differs from SMR in the activation/protection switching
 operation.  The former activates a protecting LSP via the Automatic
 Protection Switching (APS) protocol in the data plane when the
 working LSP fails, while the latter does it via control plane
 signaling.  It is therefore necessary to distinguish SMP from SMR
 during provisioning so that each node involved behaves appropriately
 in the recovery phase when activation of a protecting LSP is done.
 SMP has advantages with regard to the recovery speed compared with
 SMR.
 This document updates [RFC4872] and [RFC4873] to provide extensions
 for Generalized Multi-Protocol Label Switching (GMPLS) signaling to
 support the control of the SMP mechanism.  Specifically, it
  • defines a new LSP Protection Type, "Shared Mesh Protection", for

the LSP Flags field [RFC4872] of the PROTECTION object (see

    Section 6.1),
  • updates the definitions of the Notification (N) and Operational

(O) fields [RFC4872] of the PROTECTION object to take the new SMP

    type into account (see Section 6.2), and
  • updates the definition of the 16-bit Reserved field [RFC4873] of

the PROTECTION object to allocate 8 bits to signal the SMP

    preemption priority (see Section 6.3).
 Only the generic aspects for signaling SMP are addressed by this
 document.  The technology-specific aspects are expected to be
 addressed by other documents.
 RFC 8776 [RFC8776] defines a collection of common YANG data types for
 Traffic Engineering (TE) configuration and state capabilities.  It
 defines several identities for LSP Protection Types.  As this
 document introduces a new LSP Protection Type, [RFC8776] is expected
 to be updated to support the SMP mechanism specified in this
 document.  [YANG-TE] defines a YANG data model for the provisioning
 and management of TE tunnels, LSPs, and interfaces.  It includes some
 protection and restoration data nodes relevant to this document.
 Management aspects of the SMP mechanism are outside the scope of this
 document, and they are expected to be addressed by other documents.

2. Conventions Used in This Document

 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.
 In addition, the reader is assumed to be familiar with the
 terminology used in [RFC4872], RFC 4426 [RFC4426], and RFC 6372
 [RFC6372].

3. SMP Definition

 [G808.3] defines the generic aspects of an SMP mechanism.  [G873.3]
 defines the protection switching operation and associated protocol
 for SMP at the ODU layer.  [RFC7412] provides requirements for any
 mechanism that would be used to implement SMP in an MPLS-TP network.
 The SMP mechanism is based on precomputed protecting LSPs that are
 preconfigured into the network elements.  Preconfiguration here means
 pre-reserving resources for the protecting LSPs without activating a
 particular protecting LSP (e.g., in circuit networks, the cross-
 connects in the intermediate nodes of the protecting LSP are not
 preestablished).  Preconfiguring but not activating protecting LSPs
 allows link and node resources to be shared by the protecting LSPs of
 multiple working LSPs (which are themselves disjoint and thus
 unlikely to fail simultaneously).  Protecting LSPs are activated in
 response to failures of working LSPs or operator commands by means of
 the APS protocol, which operates in the data plane.  The APS protocol
 messages are exchanged along the protecting LSP.  SMP is always
 revertive.
 SMP is very similar to SMR, except that activation in the case of SMR
 is achieved by control plane signaling during the recovery operation,
 while the same is done for SMP by the APS protocol in the data plane.

4. Operation of SMP with GMPLS Signaling Extensions

 Consider the network topology shown in Figure 1:
                           A---B---C---D
                            \         /
                             E---F---G
                            /         \
                           H---I---J---K
                Figure 1: An Example of an SMP Topology
 The working LSPs [A,B,C,D] and [H,I,J,K] could be protected by the
 protecting LSPs [A,E,F,G,D] and [H,E,F,G,K], respectively.  Per RFC
 3209 [RFC3209], in order to achieve resource sharing during the
 signaling of these protecting LSPs, they have the same Tunnel
 Endpoint Address (as part of their SESSION object).  However, these
 addresses are not the same in this example.  Similar to SMR, this
 document defines a new LSP Protection Type of the secondary LSP as
 "Shared Mesh Protection" (see Section 6.1) to allow resource sharing
 along nodes E, F, and G.  Examples of shared resources include the
 capacity of a link and the cross-connects in a node.  In this case,
 the protecting LSPs are not merged (which is useful, since the paths
 diverge at G), but the resources along E, F, and G can be shared.
 When a failure, such as Signal Fail (SF) or Signal Degrade (SD),
 occurs on one of the working LSPs (say, working LSP [A,B,C,D]), the
 end node (say, node A) that detects the failure initiates the
 protection switching operation.  End node A will send a protection
 switching request APS message (for example, SF) to its adjacent
 (downstream) intermediate node (say, node E) to activate the
 corresponding protecting LSP and will wait for a confirmation message
 from node E.
 If the protection resource is available, node E will send the
 confirmation APS message to the end node (node A) and forward the
 switching request APS message to its adjacent (downstream) node (say,
 node F).  When the confirmation APS message is received by node A,
 the cross-connection on node A is established.  At this time, traffic
 is bridged to and selected from the protecting LSP at node A.  After
 forwarding the switching request APS message, node E will wait for a
 confirmation APS message from node F, which triggers node E to set up
 the cross-connection for the protecting LSP being activated.
 If the protection resource is not available (due to failure or being
 used by higher-priority connections), the switching will not be
 successful; the intermediate node (node E) MUST send a message to
 notify the end node (node A) (see Section 5.5).  If the resource is
 in use by a lower-priority protecting LSP, the lower-priority service
 will be removed, and the intermediate node will then follow the
 procedure as described for the case when the protection resource is
 available for the higher-priority protecting LSP.
 If node E fails to allocate the protection resource, it MUST send a
 message to notify node A (see Section 5.5).  Then, node A will stop
 bridging and selecting traffic to/from the protecting LSP and proceed
 with the procedure of removing the protection allocation according to
 the APS protocol.

5. GMPLS Signaling Extensions for SMP

 The following subsections detail how LSPs using SMP can be signaled
 in an interoperable fashion using GMPLS RSVP-TE extensions (see RFC
 3473 [RFC3473]).  This signaling enables:
 (1)  the ability to identify a "secondary protecting LSP" (LSP
      [A,E,F,G,D] or LSP [H,E,F,G,K] from Figure 1, here called the
      "secondary LSP") used to recover another "primary working LSP"
      (LSP [A,B,C,D] or LSP [H,I,J,K] from Figure 1, here called the
      "protected LSP"),
 (2)  the ability to associate the secondary LSP with the protected
      LSP,
 (3)  the capability to include information about the resources used
      by the protected LSP while instantiating the secondary LSP,
 (4)  the capability to instantiate several secondary LSPs efficiently
      during the provisioning phase, and
 (5)  the capability to support activation of a secondary LSP via the
      APS protocol in the data plane if a failure occurs.

5.1. Identifiers

 To simplify association operations, both LSPs (i.e., the protected
 LSP and the secondary LSP) belong to the same session.  Thus, the
 SESSION object MUST be the same for both LSPs.  The LSP ID, however,
 MUST be different to distinguish between the protected LSP and the
 secondary LSP.
 A new LSP Protection Type, "Shared Mesh Protection", is defined (see
 Section 6.1) for the LSP Flags field of the PROTECTION object (see
 [RFC4872]) to set up the two LSPs.  This LSP Protection Type value is
 only applicable to bidirectional LSPs as required in [G808.3].

5.2. Signaling Primary LSPs

 The PROTECTION object (see [RFC4872]) is included in the Path message
 during signaling of the primary working LSPs, with the LSP Protection
 Type value set to "Shared Mesh Protection".
 Primary working LSPs are signaled by setting in the PROTECTION object
 the S bit to 0, the P bit to 0, and the N bit to 1; and setting in
 the ASSOCIATION object the Association ID to the associated secondary
 protecting LSP_ID.
    |  Note: The N bit is set to indicate that the protection
    |  switching signaling is done via the data plane.

5.3. Signaling Secondary LSPs

 The PROTECTION object (see [RFC4872]) is included in the Path message
 during signaling of the secondary protecting LSPs, with the LSP
 Protection Type value set to "Shared Mesh Protection".
 Secondary protecting LSPs are signaled by setting in the PROTECTION
 object the S bit, the P bit, and the N bit to 1; and setting in the
 ASSOCIATION object the Association ID to the associated primary
 working LSP_ID, which MUST be known before signaling of the secondary
 LSP.  Moreover, the Path message used to instantiate the secondary
 LSP MUST include at least one PRIMARY_PATH_ROUTE object (see
 [RFC4872]) that further allows for recovery resource sharing at each
 intermediate node along the secondary path.
 With this setting, the resources for the secondary LSP MUST be pre-
 reserved but not committed at the data plane level, meaning that the
 internals of the switch need not be established until explicit action
 is taken to activate this LSP.  Activation of a secondary LSP and
 protection switching to the activated protecting LSP is done using
 the APS protocol in the data plane.
 After protection switching completes, the protecting LSP MUST be
 signaled by setting the S bit to 0 and the O bit to 1 in the
 PROTECTION object.  At this point, the link and node resources MUST
 be allocated for this LSP, which becomes a primary LSP (ready to
 carry traffic).  The formerly working LSP MAY be signaled with the A
 bit set in the ADMIN_STATUS object (see [RFC3473]).
 Support for extra traffic in SMP is left for further study.
 Therefore, mechanisms to set up LSPs for extra traffic are outside
 the scope of this document.

5.4. SMP Preemption Priority

 The SMP preemption priority of a protecting LSP is used by the APS
 protocol to resolve competition for shared resources among multiple
 protecting LSPs and is indicated in the Preemption Priority field of
 the PROTECTION object in the Path message of the protecting LSP.
 The Setup and Holding priorities in the SESSION_ATTRIBUTE object can
 be used by GMPLS to control LSP preemption, but they are not used by
 the APS to resolve competition among multiple protecting LSPs.  This
 avoids the need to define a complex policy for defining Setup and
 Holding priorities when used for both GMPLS control plane LSP
 preemption and SMP shared resource competition resolution.
 When an intermediate node on the protecting LSP receives the Path
 message, the priority value in the Preemption Priority field MUST be
 stored for that protecting LSP.  When resource competition among
 multiple protecting LSPs occurs, the APS protocol will use their
 priority values to resolve this competition.  A lower value has a
 higher priority.
 In SMP, a preempted LSP MUST NOT be terminated even after its
 resources have been deallocated.  Once the working LSP and the
 protecting LSP are configured or preconfigured, the end node MUST
 keep refreshing both working and protecting LSPs, regardless of
 failure or preemption status.

5.5. Availability of Shared Resources: The Notify Message

 When a lower-priority protecting LSP is preempted, the intermediate
 node that performed the preemption MUST send a Notify message with
 error code "Notify Error" (25) (see [RFC4872]) and error sub-code
 "Shared resources unavailable" (17) to the end nodes of that
 protecting LSP.  Upon receipt of this Notify message, the end node
 MUST stop sending and selecting traffic to/from its protecting LSP
 and try switching the traffic to another protecting LSP, if
 available.
 When a protecting LSP occupies the shared resources and they become
 unavailable, the same Notify message MUST be generated by the
 intermediate node to all the end nodes of the protecting LSPs that
 have lower SMP preemption priorities than the one that has occupied
 the shared resources.  If the shared resources become unavailable due
 to a failure in the shared resources, the same Notify message MUST be
 generated by the intermediate node to all the end nodes of the
 protecting LSPs that have been configured to use the shared
 resources.  In the case of a failure of the working LSP, these end
 nodes MUST avoid trying to switch traffic to these protecting LSPs
 that have been configured to use the shared resources and try
 switching the traffic to other protecting LSPs, if available.
 When the shared resources become available, a Notify message with
 error code "Notify Error" (25) and error sub-code "Shared resources
 available" (18) MUST be generated by the intermediate node.  The
 recipients of this Notify message are the end nodes of the lower-
 priority protecting LSPs that have been preempted and/or all the end
 nodes of the protecting LSPs that have lower SMP preemption
 priorities than the one that does not need the shared resources
 anymore.  Upon receipt of this Notify message, the end node is
 allowed to reinitiate the protection switching operation as described
 in Section 4, if it still needs the protection resource.

5.6. SMP APS Configuration

 SMP relies on APS protocol messages being exchanged between the nodes
 along the path to activate a protecting LSP.
 In order to allow the exchange of APS protocol messages, an APS
 channel has to be configured between adjacent nodes along the path of
 the protecting LSP.  This is done by means other than GMPLS
 signaling, before any protecting LSP has been set up.  Therefore,
 there are likely additional requirements for APS configuration that
 are outside the scope of this document.
 Depending on the APS protocol message format, the APS protocol may
 use different identifiers than GMPLS signaling to identify the
 protecting LSP.
 Since the APS protocol is left for further study per [G808.3], it can
 be assumed that the APS message format and identifiers are technology
 specific and/or vendor specific.  Therefore, additional requirements
 for APS configuration are outside the scope of this document.

6. Updates to PROTECTION Object

 GMPLS extension requirements for SMP introduce several updates to the
 PROTECTION object (see [RFC4872]), as detailed below.

6.1. New Protection Type

 A new LSP Protection Type, "Shared Mesh Protection", is added in the
 PROTECTION object.  This LSP Protection Type value is only applicable
 to bidirectional LSPs.
 LSP (Protection Type) Flags:
    0x20: Shared Mesh Protection
 The rules defined in Section 14.2 of [RFC4872] ensure that all the
 nodes along an SMP LSP are SMP aware.  Therefore, there are no
 backward-compatibility issues.

6.2. Updates to Definitions of Notification and Operational Bits

 The definitions of the N and O bits in Section 14.1 of [RFC4872] are
 replaced as follows:
 Notification (N): 1 bit
    When set to 1, this bit indicates that the control plane message
    exchange is only used for notification during protection
    switching.  When set to 0 (default), it indicates that the control
    plane message exchanges are used for purposes of protection
    switching.  The N bit is only applicable when the LSP Protection
    Type Flag is set to 0x04 (1:N Protection with Extra-Traffic), 0x08
    (1+1 Unidirectional Protection), 0x10 (1+1 Bidirectional
    Protection), or 0x20 (Shared Mesh Protection).  The N bit MUST be
    set to 0 in any other case.  If 0x20 (SMP), the N bit MUST be set
    to 1.
 Operational (O): 1 bit
    When set to 1, this bit indicates that the protecting LSP is
    carrying traffic after protection switching.  The O bit is only
    applicable when (1) the P bit is set to 1 and (2) the LSP
    Protection Type Flag is set to 0x04 (1:N Protection with Extra-
    Traffic), 0x08 (1+1 Unidirectional Protection), 0x10 (1+1
    Bidirectional Protection), or 0x20 (Shared Mesh Protection).  The
    O bit MUST be set to 0 in any other case.

6.3. Preemption Priority

 [RFC4872] reserved a 32-bit field in the PROTECTION object header.
 Subsequently, [RFC4873] allocated several bits from that field and
 left the remainder of the bits reserved.  This specification further
 allocates the Preemption Priority field from the remaining formerly
 reserved bits.  The 32-bit field in the PROTECTION object as defined
 in [RFC4872] and modified by [RFC4873] is updated by this document as
 follows:
     0                   1                   2                   3
     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |I|R|   Reserved    | Seg.Flags |   Reserved    | Preempt Prio  |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 Preemption Priority (Preempt Prio): 8 bits
    This field indicates the SMP preemption priority of a protecting
    LSP, when the LSP Protection Type field indicates "Shared Mesh
    Protection".  The SMP preemption priority value is configured at
    the end nodes of the protecting LSP by a network operator.  A
    lower value has a higher priority.  The decision regarding how
    many priority levels should be implemented in an SMP network is
    left to network operators.
 See [RFC4873] for the definitions of the other fields.

7. IANA Considerations

 IANA maintains a group of registries called "Resource Reservation
 Protocol (RSVP) Parameters", which includes the "Error Codes and
 Globally-Defined Error Value Sub-Codes" registry.  IANA has added the
 following values to the "Sub-Codes - 25 Notify Error" subregistry,
 which lists error value sub-codes that may be used with error code
 25.  IANA has allocated the following error value sub-codes (Table 1)
 for use with this error code as described in this document.
         +=======+==============================+===========+
         | Value | Description                  | Reference |
         +=======+==============================+===========+
         | 17    | Shared resources unavailable | RFC 9270  |
         +-------+------------------------------+-----------+
         | 18    | Shared resources available   | RFC 9270  |
         +-------+------------------------------+-----------+
                     Table 1: New Error Sub-Codes

8. Security Considerations

 Since this document makes use of the exchange of RSVP messages that
 include a Notify message, the security threats discussed in [RFC4872]
 also apply to this document.
 Additionally, it may be possible to cause disruption to traffic on
 one protecting LSP by targeting a link used by the primary LSP of
 another, higher-priority LSP somewhere completely different in the
 network.  For example, in Figure 1, assume that the preemption
 priority of LSP [A,E,F,G,D] is higher than that of LSP [H,E,F,G,K]
 and the protecting LSP [H,E,F,G,K] is being used to transport
 traffic.  If link B-C is attacked, traffic on LSP [H,E,F,G,K] can be
 disrupted.  For this reason, it is important not only to use security
 mechanisms as discussed in [RFC4872] but also to acknowledge that
 detailed knowledge of a network's topology, including routes and
 priorities of LSPs, can help an attacker better target or improve the
 efficacy of an attack.

9. References

9.1. Normative References

 [G808.3]   International Telecommunication Union, "Generic protection
            switching - Shared mesh protection", ITU-T Recommendation
            G.808.3, October 2012,
            <https://www.itu.int/rec/T-REC-G.808.3>.
 [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
            Requirement Levels", BCP 14, RFC 2119,
            DOI 10.17487/RFC2119, March 1997,
            <https://www.rfc-editor.org/info/rfc2119>.
 [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,
            <https://www.rfc-editor.org/info/rfc3209>.
 [RFC3473]  Berger, L., Ed., "Generalized Multi-Protocol Label
            Switching (GMPLS) Signaling Resource ReserVation Protocol-
            Traffic Engineering (RSVP-TE) Extensions", RFC 3473,
            DOI 10.17487/RFC3473, January 2003,
            <https://www.rfc-editor.org/info/rfc3473>.
 [RFC4426]  Lang, J., Ed., Rajagopalan, B., Ed., and D. Papadimitriou,
            Ed., "Generalized Multi-Protocol Label Switching (GMPLS)
            Recovery Functional Specification", RFC 4426,
            DOI 10.17487/RFC4426, March 2006,
            <https://www.rfc-editor.org/info/rfc4426>.
 [RFC4872]  Lang, J P., Ed., Rekhter, Y., Ed., and D. Papadimitriou,
            Ed., "RSVP-TE Extensions in Support of End-to-End
            Generalized Multi-Protocol Label Switching (GMPLS)
            Recovery", RFC 4872, DOI 10.17487/RFC4872, May 2007,
            <https://www.rfc-editor.org/info/rfc4872>.
 [RFC4873]  Berger, L., Bryskin, I., Papadimitriou, D., and A. Farrel,
            "GMPLS Segment Recovery", RFC 4873, DOI 10.17487/RFC4873,
            May 2007, <https://www.rfc-editor.org/info/rfc4873>.
 [RFC8174]  Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
            2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
            May 2017, <https://www.rfc-editor.org/info/rfc8174>.

9.2. Informative References

 [G873.3]   International Telecommunication Union, "Optical transport
            network - Shared mesh protection", ITU-T Recommendation
            G.873.3, September 2017,
            <https://www.itu.int/rec/T-REC-G.873.3-201709-I/en>.
 [RFC6372]  Sprecher, N., Ed. and A. Farrel, Ed., "MPLS Transport
            Profile (MPLS-TP) Survivability Framework", RFC 6372,
            DOI 10.17487/RFC6372, September 2011,
            <https://www.rfc-editor.org/info/rfc6372>.
 [RFC7412]  Weingarten, Y., Aldrin, S., Pan, P., Ryoo, J., and G.
            Mirsky, "Requirements for MPLS Transport Profile (MPLS-TP)
            Shared Mesh Protection", RFC 7412, DOI 10.17487/RFC7412,
            December 2014, <https://www.rfc-editor.org/info/rfc7412>.
 [RFC8776]  Saad, T., Gandhi, R., Liu, X., Beeram, V., and I. Bryskin,
            "Common YANG Data Types for Traffic Engineering",
            RFC 8776, DOI 10.17487/RFC8776, June 2020,
            <https://www.rfc-editor.org/info/rfc8776>.
 [YANG-TE]  Saad, T., Gandhi, R., Liu, X., Beeram, V.P., Bryskin, I.,
            and O. Gonzalez de Dios, "A YANG Data Model for Traffic
            Engineering Tunnels, Label Switched Paths and Interfaces",
            Work in Progress, Internet-Draft, draft-ietf-teas-yang-te-
            30, 11 July 2022, <https://datatracker.ietf.org/doc/html/
            draft-ietf-teas-yang-te-30>.

Acknowledgements

 The authors would like to thank Adrian Farrel, Vishnu Pavan Beeram,
 Tom Petch, Ines Robles, John Scudder, Dale Worley, Dan Romascanu,
 Éric Vyncke, Roman Danyliw, Paul Wouters, Lars Eggert, Francesca
 Palombini, and Robert Wilton for their valuable comments and
 suggestions on this document.

Contributors

 The following person contributed significantly to the content of this
 document and should be considered a coauthor.
 Yuji Tochio
 Fujitsu
 Email: tochio@fujitsu.com

Authors' Addresses

 Jia He
 Huawei Technologies
 F3-1B, R&D Center, Huawei Industrial Base
 Bantian, Longgang District
 Shenzhen
 China
 Email: hejia@huawei.com
 Italo Busi
 Huawei Technologies
 Email: italo.busi@huawei.com
 Jeong-dong Ryoo
 ETRI
 218 Gajeongno
 Yuseong-gu
 Daejeon
 34129
 South Korea
 Phone: +82-42-860-5384
 Email: ryoo@etri.re.kr
 Bin Yeong Yoon
 ETRI
 Email: byyun@etri.re.kr
 Peter Park
 KT
 Email: peter.park@kt.com
/home/gen.uk/domains/wiki.gen.uk/public_html/data/pages/rfc/rfc9270.txt · Last modified: 2022/08/11 13:21 by 127.0.0.1

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