Application-Specific Attributes Advertisement with BGP Link-State
draft-ietf-idr-bgp-ls-app-specific-attr-03

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Inter-Domain Routing                                       K. Talaulikar
Internet-Draft                                                 P. Psenak
Intended status: Standards Track                           Cisco Systems
Expires: January 26, 2021                                    J. Tantsura
                                                                  Apstra
                                                           July 25, 2020

   Application-Specific Attributes Advertisement with BGP Link-State
               draft-ietf-idr-bgp-ls-app-specific-attr-03

Abstract

   Various link attributes have been defined in link-state routing
   protocols like OSPF and IS-IS in the context of the MPLS Traffic
   Engineering (TE) and GMPLS.  BGP Link-State (BGP-LS) extensions have
   been defined to distribute these attributes along with other topology
   information from these link-state routing protocols.  Many of these
   link attributes can be used for applications other than MPLS-TE or
   GMPLS.

   Extensions to link-state routing protocols have been defined for such
   link attributes that enable distribution of their application-
   specific values.  This document defines extensions to BGP-LS address-
   family to enable advertisement of these application-specific
   attributes as a part of the topology information from the network.

Status of This Memo

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

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF).  Note that other groups may also distribute
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at https://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on January 26, 2021.

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Copyright Notice

   Copyright (c) 2020 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
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   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
     1.1.  Requirements Language . . . . . . . . . . . . . . . . . .   3
   2.  Application Specific Link Attributes TLV  . . . . . . . . . .   3
   3.  Application Specific Link Attributes  . . . . . . . . . . . .   5
   4.  Procedures  . . . . . . . . . . . . . . . . . . . . . . . . .   7
   5.  Deployment Considerations . . . . . . . . . . . . . . . . . .   9
   6.  Backward Compatibility  . . . . . . . . . . . . . . . . . . .   9
   7.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  10
   8.  Manageability Considerations  . . . . . . . . . . . . . . . .  10
     8.1.  Operational Considerations  . . . . . . . . . . . . . . .  10
     8.2.  Management Considerations . . . . . . . . . . . . . . . .  10
   9.  Security Considerations . . . . . . . . . . . . . . . . . . .  10
   10. Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .  11
   11. References  . . . . . . . . . . . . . . . . . . . . . . . . .  11
     11.1.  Normative References . . . . . . . . . . . . . . . . . .  11
     11.2.  Informative References . . . . . . . . . . . . . . . . .  11
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  12

1.  Introduction

   Various link attributes have been defined in link-state routing
   protocols (viz., IS-IS [RFC1195], OSPFv2 [RFC2328] and OSPFv3
   [RFC5340] ) in the context of the MPLS traffic engineering and GMPLS.
   All these attributes are distributed by these protocols using TLVs
   that were originally defined for traditional MPLS Traffic Engineering
   (i.e., using RSVP-TE [RFC3209]) or GMPLS [RFC4202] applications.

   In recent years new applications have been introduced that have use
   cases for many of the link attributes historically used by RSVP-TE
   and GMPLS.  Such applications include Segment Routing (SR) [RFC8402]
   and Loop Free Alternates (LFA) [RFC5286].  This has introduced

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   ambiguity in that if a deployment includes a mix of RSVP-TE support
   and SR support (for example) it is not possible to unambiguously
   indicate which advertisements are to be used by RSVP-TE and which
   advertisements are to be used by SR.  If the topologies are fully
   congruent this may not be an issue, but any incongruence leads to
   ambiguity.  An additional issue arises in cases where both
   applications are supported on a link but the link attribute values
   associated with each application differ.  Current advertisements do
   not support advertising application-specific values for the same
   attribute on a specific link.  IGP Flexible Algorithm
   [I-D.ietf-lsr-flex-algo] is one such application use case that MAY
   use application-specific link attributes.

   [I-D.ietf-ospf-te-link-attr-reuse] and [I-D.ietf-isis-te-app] define
   extensions for OSPF and IS-IS respectively that address these issues.
   Also, as evolution of use cases for link attributes can be expected
   to continue in the years to come, these documents define a solution
   that is easily extensible to the introduction of new applications and
   new use cases.

   BGP Link-State extensions [RFC7752] have been specified to enable
   distribution of the link-state topology information from the IGPs to
   an application like a controller or Path Computation Engine (PCE) via
   BGP.  The controller/PCE gets the end-to-end topology information
   across IGP domains so it can perform path computations for use cases
   like end-to-end traffic engineering (TE) using RSVP-TE or SR-based
   mechanisms.  A similar challenge to what was described above is hence
   also faced by such centralized computation entities.

   There is thus a need for BGP-LS extensions to also report link
   attributes on a per-application basis on the same lines as introduced
   in the link-state routing protocols.  This document defines these
   BGP-LS extensions and also covers the backward compatibility issues
   related to existing BGP-LS deployments.

1.1.  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.

2.  Application Specific Link Attributes TLV

   The BGP-LS [RFC7752] specifies the Link NLRI for advertisement of
   links and their attributes using the BGP-LS Attribute.  The
   Application-Specific Link Attributes (ASLA) TLV is a new optional

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   top-level BGP-LS Attribute TLV that is introduced for Link NLRIs.  It
   is defined such that it may act as a container for certain existing
   and future link attributes that require application-specific
   definition.

   The format of this TLV is as follows and is similar to the
   corresponding ASLA sub-TLVs defined for OSPF and IS-IS in
   [I-D.ietf-ospf-te-link-attr-reuse] and [I-D.ietf-isis-te-app]
   respectively.

       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
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |              Type             |             Length            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |     SABML     |     UDABML    |            Reserved           |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |     Standard Application Identifier Bit Mask (variable)      //
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |    User-Defined Application Identifier Bit Mask (variable)   //
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                      Link Attribute sub-TLVs                 //
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

            Figure 1: Application-Specific Link Attributes TLV

   where:

   o  Type: 1122

   o  Length: variable.

   o  SABML : Standard Application Identifier Bit Mask Length in octets.
      The values MUST be 0, 4, or 8.  If the Standard Application
      Identifier Bit Mask is not present, the SABML MUST be set to 0.

   o  UDABML : User-Defined Application Identifier Bit Mask Length in
      octets.  The values MUST be 0, 4, or 8.  If the User-Defined
      Application Identifier Bit Mask is not present, the UDABML MUST be
      set to 0.

   o  Standard Application Identifier Bit Mask : of size 0, 4, or 8
      octets as indicated by the SABML.  Optional set of bits, where
      each bit represents a single standard application.  The bits are
      defined in the IANA "IGP Parameters" registries under the "Link
      Attribute Applications" registry [I-D.ietf-isis-te-app].

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   o  User-Defined Application Identifier Bit Mask : of size 0, 4, or 8
      octets as indicated by the UDABML.  Optional set of bits, where
      each bit represents a single user-defined application.  The bits
      are not managed or assigned by IANA or any other standards body
      and definition is left to the implementation.

   o  sub-TLVs : BGP-LS Attribute TLVs corresponding to the Link NLRI
      that are application-specific (as specified in Section 3) are
      included as sub-TLVs of the ASLA TLV.

   An ASLA TLV with both the SABML and UDABML set to 0 (i.e. without any
   application identifier bit masks) indicates that the link attribute
   sub-TLVs that it encloses are applicable for all applications.

   The ASLA TLV and its sub-TLVs can only be added to the BGP-LS
   Attribute associated with the Link NLRI of the node that originates
   the underlying IGP link attribute TLVs/sub-TLVs.  The procedures for
   originating link attributes in the ASLA TLV from underlying IGPs are
   specified in Section 4.

   When the node is not running any of the IGPs but running a protocol
   like BGP, then the link attributes for the node's local links MAY be
   originated as part of the BGP-LS Attribute using the ASLA TLV and its
   sub-TLVs within the Link NLRI corresponding to the local node.

3.  Application Specific Link Attributes

   Several BGP-LS Attribute TLVs corresponding to the Link NLRI are
   defined in BGP-LS and more may be added in the future.  The following
   types of link attributes are required to be considered as application
   specific.

   o  those that have different values for different applications (e.g.,
      a different TE metric value used for RSVP-TE than for SR TE)

   o  those that are applicable to multiple applications but need to be
      used only by specific application (e.g., certain SRLG values are
      configured on a node for LFA but the same do not need to be used
      for RSVP-TE)

   The following table lists the currently defined BGP-LS Attributes
   TLVs corresponding to Link NLRI that have application-specific
   semantics.  They were originally defined with semantics for RSVP-TE
   and GMPLS applications.

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   +----------+----------------------+---------------------------------+
   | TLV Code | Description          | Reference Document              |
   |  Point   |                      |                                 |
   +----------+----------------------+---------------------------------+
   |   1088   | Administrative group | [RFC7752]                       |
   |          | (color)              |                                 |
   |   1092   | TE Metric            | [RFC7752]                       |
   |   1096   | SRLG                 | [RFC7752]                       |
   |   1114   | Unidirectional link  | [RFC8571]                       |
   |          | delay                |                                 |
   |   1115   | Min/Max              | [RFC8571]                       |
   |          | Unidirectional link  |                                 |
   |          | delay                |                                 |
   |   1116   | Unidirectional link  | [RFC8571]                       |
   |          | delay variation      |                                 |
   |   1117   | Unidirectional       | [RFC8571]                       |
   |          | packet loss          |                                 |
   |   1118   | Unidirectional       | [RFC8571]                       |
   |          | residual bandwidth   |                                 |
   |   1119   | Unidirectional       | [RFC8571]                       |
   |          | available bandwidth  |                                 |
   |   1120   | Unidirectional       | [RFC8571]                       |
   |          | bandwidth            |                                 |
   |          | utilization          |                                 |
   |   1173   | Extended             | [I-D.ietf-idr-eag-distribution] |
   |          | Administrative group |                                 |
   |          | (color)              |                                 |
   +----------+----------------------+---------------------------------+

     Table 1: BGP-LS Attribute TLVs also used as sub-TLVs of ASLA TLV

   All the BGP-LS Attribute TLVs defined in the table above are
   RECOMMENDED to continue to be advertised at the top-level in the BGP-
   LS Attribute for carrying attributes specific to RSVP-TE without the
   use of the ASLA TLV.

   When a new link attribute is introduced, it may be thought of as
   being specific to only a single application.  However, subsequently,
   it may be also shared by other applications and/or require
   application-specific values.  In such cases, it is RECOMMENDED to err
   on the side of caution and define such attributes as application-
   specific to ensure flexibility in the future.

   BGP-LS Attribute TLVs corresponding to Link NLRI that are defined in
   the future MUST specify if they are application-specific and hence
   are REQUIRED to be encoded within an ASLA TLV.

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   Only application-specific link attributes need to be advertised
   within the ASLA TLV.  Link attributes that do not have application-
   specific semantics SHOULD NOT be advertised within the ASLA TLV.
   Receivers SHOULD ignore any non-application-specific attribute sub-
   TLVs within the ASLA TLV.

4.  Procedures

   The procedures described in this section apply to networks where all
   BGP-LS originators and consumers support this specification.  The
   backward compatibility aspects and operations in deployments where
   there are some BGP-LS originators or consumers that do not support
   this specification are described further in Section 6.

   The BGP-LS originator learns of the association of an application-
   specific attribute to one or more applications from either the
   underlying IGP protocol LSA/LSPs from which it is advertising the
   topology information or from the local node configuration when
   advertising attributes for the local node only.

   The association of an application-specific link attribute with a
   specific application context when advertising attributes for the
   local node only (e.g., when running BGP as the only routing protocol)
   is an implementation specific matter and outside the scope of this
   document.

   [I-D.ietf-ospf-te-link-attr-reuse] and [I-D.ietf-isis-te-app] specify
   the mechanisms for advertising application-specific link attributes
   in OSPFv2/v3 and IS-IS respectively.  These IGP specifications also
   describe the backward compatibility aspects and the existing RSVP-TE/
   GMPLS specific TLV encoding mechanisms in the respective protocols.

   A BGP-LS originator node that is advertising link-state information
   from the underlying IGP determines the protocol encoding of
   application-specific link attributes based on the following rules:

   1.  Application-specific link attributes received from an IGP node
       using existing RSVP-TE/GMPLS encodings MUST be encoded using the
       respective BGP-LS top-level TLVs listed in Table 1.

   2.  Application-specific link attributes received from an IGP node
       using ASLA sub-TLV MUST be encoded in the BGP-LS ASLA TLV as sub-
       TLVs.

   3.  In case of IS-IS, the following specific procedures are to be
       followed:

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       *  When application-specific link attributes are received from a
          node with the L bit set in the ASLA sub-TLV AND application
          bits other than RSVP-TE are set in the application bit masks
          then the application-specific link attributes advertised in
          the corresponding legacy IS-IS TLVs/sub-TLVs MUST be encoded
          within the BGP-LS ASLA TLV as sub-TLVs with the application
          bits, other than the RSVP-TE bit, copied from the IS-IS ASLA
          sub-TLV.  The link attributes advertised in the legacy IS-IS
          TLVs/sub-TLVs are also advertised in BGP-LS top-level TLVs
          listed in Table 1.  Note that this is true regardless of
          whether the RSVP-TE bit was set in the IS-IS ASLA TLV/sub-TLV.

       *  When the ASLA sub-TLV has the RSVP-TE application bit set,
          then the link attributes for the corresponding ASLA sub-TLV
          MUST be encoded using the respective BGP-LS top-level TLVs
          listed in Table 1.

       *  [I-D.ietf-isis-te-app] allows the advertisement of the Maximum
          Link Bandwidth within an ASLA sub-TLV even though it is not an
          application-specific attribute.  However, when originating the
          Maximum Link Bandwidth into BGP-LS, the attribute MUST be
          encoded only in the top-level BGP-LS Maximum Link Bandwidth
          TLV (1089) and not within the BGP-LS ASLA TLV.

       *  [I-D.ietf-isis-te-app] also allows the advertisement of the
          Maximum Reservable Link Bandwidth and the Unreserved Bandwidth
          within an ASLA sub-TLV even though these attributes are
          specific to RSVP-TE application.  However, when originating
          the Maximum Reservable Link Bandwidth and Unreserved Bandwidth
          into BGP-LS, these attributes MUST be encoded only in the BGP-
          LS top-level Maximum Reservable Link Bandwidth TLV (1090) and
          Unreserved Bandwidth TLV (1091) respectively and not within
          the BGP-LS ASLA TLV.

   These rules ensure that a BGP-LS originator performs the
   advertisement for all application-specific link attributes from the
   IGP nodes that support or do not support the ASLA extension.
   Furthermore, it also ensures that the top-level BGP-LS TLVs defined
   for RSVP-TE and GMPLS applications continue to be used for
   advertisement of their application-specific attributes.

   A BGP-LS consumer node would normally receive all the application-
   specific link attributes corresponding to RSVP-TE and GMPLS
   applications as existing top-level BGP-LS TLVs while for other
   applications they are encoded in ASLA TLV(s) with appropriate
   applicable bit mask setting.  A BGP-LS consumer that implements this
   specification SHOULD prefer the application-specific attribute value

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   received via sub-TLVs within the ASLA TLV over the value received via
   the top level TLVs.

5.  Deployment Considerations

   SR-TE and LFA applications have been deployed in some networks using
   the IGP link attributes defined originally for RSVP-TE as discussed
   in [I-D.ietf-ospf-te-link-attr-reuse] and [I-D.ietf-isis-te-app].
   The corresponding BGP-LS top-level link attribute TLVs originally
   defined for RSVP-TE have also been similarly used for SR-TE and LFA
   applications by BGP-LS consumers.  Such usage MAY continue without
   requiring the support of the application-specific link attribute
   encodings described in this document as long as the following
   conditions are met:

   o  The application is SRTE or LFA and RSVP-TE is not deployed
      anywhere in the network

   o  The application is SRTE or LFA, RSVP-TE is deployed in the
      network, and both the set of links on which SRTE and/or LFA
      advertisements are required and the attribute values used by SRTE
      and/or LFA on all such links is fully congruent with the links and
      attribute values used by RSVP-TE

6.  Backward Compatibility

   The backward compatibility aspects for BGP-LS are associated with the
   originators (i.e., nodes) and consumers (e.g., PCE, controllers,
   applications, etc.) of the topology information.  BGP-LS
   implementations have been originating link attributes and consuming
   them without any application-specific scoping prior to the extensions
   specified in this document.

   IGP backwards compatibility aspects associated with application-
   specific link attributes for RSVP-TE, SRTE and LFA applications are
   discussed in the Backward Compatibility sections of
   [I-D.ietf-ospf-te-link-attr-reuse] and [I-D.ietf-isis-te-app].  While
   the backwards compatibility aspects ensure compatibility of IGP
   advertisements, they also serve to ensure the backward compatibility
   of the BGP-LS advertisements used by BGP-LS consumers.  In
   deployments where the BGP-LS originators or consumers do not support
   the extensions specified in this document, the IGPs need to continue
   to advertise link attributes intended for use by SRTE and LFA
   applications using the RSVP-TE/GMPLS encodings.  This allows BGP-LS
   advertisements to be consistent with the behavior prior to the
   extensions defined in this document

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   It is RECOMMENDED that nodes that support this specification are
   selected as originators of BGP-LS information when advertising the
   link-state information from the IGPs.

7.  IANA Considerations

   This document requests assignment of code-points from the registry
   "BGP-LS Node Descriptor, Link Descriptor, Prefix Descriptor, and
   Attribute TLVs" based on table below which reflects the values
   assigned via the early allocation process.  The column "IS-IS TLV/
   Sub-TLV" defined in the registry does not require any value and
   should be left empty.

   +------------+------------------------------------------+----------+
   | Code Point |         Description                      | Length   |
   +------------+------------------------------------------+----------+
   |   1122     | Application-Specific Link Attributes TLV | variable |
   +------------+------------------------------------------+----------+

8.  Manageability Considerations

   This section is structured as recommended in [RFC5706].

   The new protocol extensions introduced in this document augment the
   existing IGP topology information defined in [RFC7752].  Procedures
   and protocol extensions defined in this document do not affect the
   BGP protocol operations and management other than as discussed in the
   Manageability Considerations section of [RFC7752].  Specifically, the
   malformed NLRIs attribute tests in the Fault Management section of
   [RFC7752] now encompass the BGP-LS TLVs defined in this document.

8.1.  Operational Considerations

   No additional operation considerations are defined in this document.

8.2.  Management Considerations

   No additional management considerations are defined in this document.

9.  Security Considerations

   The new protocol extensions introduced in this document augment the
   existing IGP topology information defined in [RFC7752].  Procedures
   and protocol extensions defined in this document do not affect the
   BGP security model other than as discussed in the Security
   Considerations section of [RFC7752].

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10.  Acknowledgements

   The authors would like to thank Les Ginsberg, Baalajee S, Amalesh
   Maity, and Acee Lindem for their review and feedback on this
   document.

11.  References

11.1.  Normative References

   [I-D.ietf-isis-te-app]
              Ginsberg, L., Psenak, P., Previdi, S., Henderickx, W., and
              J. Drake, "IS-IS Application-Specific Link Attributes",
              draft-ietf-isis-te-app-19 (work in progress), June 2020.

   [I-D.ietf-ospf-te-link-attr-reuse]
              Psenak, P., Ginsberg, L., Henderickx, W., Tantsura, J.,
              and J. Drake, "OSPF Application-Specific Link Attributes",
              draft-ietf-ospf-te-link-attr-reuse-16 (work in progress),
              June 2020.

   [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>.

   [RFC7752]  Gredler, H., Ed., Medved, J., Previdi, S., Farrel, A., and
              S. Ray, "North-Bound Distribution of Link-State and
              Traffic Engineering (TE) Information Using BGP", RFC 7752,
              DOI 10.17487/RFC7752, March 2016,
              <https://www.rfc-editor.org/info/rfc7752>.

   [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>.

11.2.  Informative References

   [I-D.ietf-idr-eag-distribution]
              Wang, Z., WU, Q., Tantsura, J., and K. Talaulikar,
              "Distribution of Traffic Engineering Extended Admin Groups
              using BGP-LS", draft-ietf-idr-eag-distribution-12 (work in
              progress), May 2020.

   [I-D.ietf-lsr-flex-algo]
              Psenak, P., Hegde, S., Filsfils, C., Talaulikar, K., and
              A. Gulko, "IGP Flexible Algorithm", draft-ietf-lsr-flex-
              algo-08 (work in progress), July 2020.

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   [RFC1195]  Callon, R., "Use of OSI IS-IS for routing in TCP/IP and
              dual environments", RFC 1195, DOI 10.17487/RFC1195,
              December 1990, <https://www.rfc-editor.org/info/rfc1195>.

   [RFC2328]  Moy, J., "OSPF Version 2", STD 54, RFC 2328,
              DOI 10.17487/RFC2328, April 1998,
              <https://www.rfc-editor.org/info/rfc2328>.

   [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>.

   [RFC4202]  Kompella, K., Ed. and Y. Rekhter, Ed., "Routing Extensions
              in Support of Generalized Multi-Protocol Label Switching
              (GMPLS)", RFC 4202, DOI 10.17487/RFC4202, October 2005,
              <https://www.rfc-editor.org/info/rfc4202>.

   [RFC5286]  Atlas, A., Ed. and A. Zinin, Ed., "Basic Specification for
              IP Fast Reroute: Loop-Free Alternates", RFC 5286,
              DOI 10.17487/RFC5286, September 2008,
              <https://www.rfc-editor.org/info/rfc5286>.

   [RFC5340]  Coltun, R., Ferguson, D., Moy, J., and A. Lindem, "OSPF
              for IPv6", RFC 5340, DOI 10.17487/RFC5340, July 2008,
              <https://www.rfc-editor.org/info/rfc5340>.

   [RFC5706]  Harrington, D., "Guidelines for Considering Operations and
              Management of New Protocols and Protocol Extensions",
              RFC 5706, DOI 10.17487/RFC5706, November 2009,
              <https://www.rfc-editor.org/info/rfc5706>.

   [RFC8402]  Filsfils, C., Ed., Previdi, S., Ed., Ginsberg, L.,
              Decraene, B., Litkowski, S., and R. Shakir, "Segment
              Routing Architecture", RFC 8402, DOI 10.17487/RFC8402,
              July 2018, <https://www.rfc-editor.org/info/rfc8402>.

   [RFC8571]  Ginsberg, L., Ed., Previdi, S., Wu, Q., Tantsura, J., and
              C. Filsfils, "BGP - Link State (BGP-LS) Advertisement of
              IGP Traffic Engineering Performance Metric Extensions",
              RFC 8571, DOI 10.17487/RFC8571, March 2019,
              <https://www.rfc-editor.org/info/rfc8571>.

Authors' Addresses

Talaulikar, et al.      Expires January 26, 2021               [Page 12]
Internet-Draft  BGP-LS Extns for App Specific Attributes       July 2020

   Ketan Talaulikar
   Cisco Systems
   India

   Email: ketant@cisco.com

   Peter Psenak
   Cisco Systems
   Slovakia

   Email: ppsenak@cisco.com

   Jeff Tantsura
   Apstra

   Email: jefftant.ietf@gmail.com

Talaulikar, et al.      Expires January 26, 2021               [Page 13]