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Versions: (draft-zhuang-idr-bgp-ls-sbfd-extensions) 00 01

Network Working Group                                              Z. Li
Internet-Draft                                                Sam aldrin
Intended status: Standards Track                     Huawei Technologies
Expires: May 3, 2017                                         J. Tantsura
                                                               G. Mirsky
                                                                Ericsson
                                                               S. Zhuang
                                                     Huawei Technologies
                                                        October 30, 2016


               BGP Link-State Extensions for Seamless BFD
                 draft-li-idr-bgp-ls-sbfd-extensions-00

Abstract

   [RFC7880] defines a simplified mechanism to use Bidirectional
   Forwarding Detection (BFD) with large portions of negotiation aspects
   eliminated, thus providing benefits such as quick provisioning as
   well as improved control and flexibility to network nodes initiating
   the path monitoring.  The link-state routing protocols (IS-IS, OSPF
   and OSPFv3) have been extended to advertise the Seamless BFD (S-BFD)
   Discriminators.

   This draft defines extensions to the BGP Link-state address-family to
   carry the S-BFD Discriminators information via BGP.

Requirements Language

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in RFC 2119 [RFC2119].

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 http://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."




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   This Internet-Draft will expire on May 3, 2017.

Copyright Notice

   Copyright (c) 2016 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
   (http://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 Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   3
   3.  Problem and Requirement . . . . . . . . . . . . . . . . . . .   3
   4.  BGP-LS Extensions for S-BFD Discriminators Exchanging . . . .   3
   5.  Operations  . . . . . . . . . . . . . . . . . . . . . . . . .   6
   6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   6
   7.  Security Considerations . . . . . . . . . . . . . . . . . . .   6
   8.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   6
   9.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   6
     9.1.  Normative References  . . . . . . . . . . . . . . . . . .   6
     9.2.  Informative References  . . . . . . . . . . . . . . . . .   6
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   7

1.  Introduction

   [RFC7880] defines a simplified mechanism to use Bidirectional
   Forwarding Detection (BFD)[RFC5880] with large portions of
   negotiation aspects eliminated, thus providing benefits such as quick
   provisioning as well as improved control and flexibility to network
   nodes initiating the path monitoring.

   [RFC7883] defines a mean of advertising one or more S-BFD
   Discriminators using the IS-IS Router Capability TLV.  [RFC7884]
   defines a new OSPF Router Information (RI) TLV that allows OSPF
   routers to flood the S-BFD discriminator values associated with a
   target network identifier.  This mechanism is applicable to both
   OSPFv2 and OSPFv3.





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   The link-state routing protocols (IS-IS, OSPF and OSPFv3) have been
   extended to advertise the S-BFD Discriminators.  But flooding based
   propagation of the S-BFD Discriminators using IGPs is limited by the
   perimeter of the IGP domain.  For advertising the S-BFD
   Discriminators which span across IGP domains (e.g. multiple ASes),
   the Border Gateway Protocol (BGP) is better suited as its propagation
   perimeter is not limited like the IGPs.

   This draft defines extensions to the BGP Link-state address-family to
   carry the S-BFD Discriminators information via BGP.

2.  Terminology

   This memo makes use of the terms defined in [RFC7880].

3.  Problem and Requirement

   Seamless MPLS [I-D.ietf-mpls-seamless-mpls] extends the core domain
   and integrates aggregation and access domains into a single MPLS
   domain.  In a large network, the core and aggregation networks can be
   organized as different autonomous systems.  Although the core and
   aggregation networks are segmented into different autonomous systems,
   but an E2E LSP will be created using hierarchical-labeled BGP LSPs
   based on iBGP-labeled unicast within each AS, and eBGP-labeled
   unicast to extend the LSP across AS boundaries.  Meanwhile, the
   customer will see only two service-end points in the Seamless MPLS
   network.  In order to detect the possible failure quickly and protect
   the network/trigger re-routing, BFD MAY be used for the Service Layer
   (e.g.  for MPLS VPNs, PW ) and the Transport Layer, so the need
   arises that the BFD session has to span across AS domain.

   The link-state routing protocols (IS-IS, OSPF and OSPFv3) have been
   extended to advertise the S-BFD Discriminators.  But flooding based
   propagation of the S-BFD Discriminators using IGPs is limited by the
   perimeter of the IGP domain.  For advertising the S-BFD
   Discriminators which span across IGP domains (e.g. multiple ASes),
   the Border Gateway Protocol (BGP) is better suited as its propagation
   perimeter is not limited like the IGPs.  This draft defines
   extensions requirement to the BGP Link-state address-family to carry
   the S-BFD Discriminators information via BGP.

4.  BGP-LS Extensions for S-BFD Discriminators Exchanging

   The BGP-LS NLRI can be a node NLRI, a link NLRI or a prefix NLRI.
   The corresponding BGP-LS attribute is a node attribute, a link
   attribute or a prefix attribute.  BGP-LS [RFC7752] defines the TLVs
   that map link-state information to BGP-LS NLRI and BGP-LS attribute.




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   This document adds additional BGP- LS attribute TLVs to encode the
   S-BFD Discriminators information.

   [RFC7880] defines the following TLVs to encode the S-BFD
   Discriminators information.

   The ISIS Router CAPABILITY TLV as defined in [RFC4971] will be used
   to advertise S-BFD discriminators.  A new Sub-TLV is defined as
   described below.  S-BFD Discriminators Sub-TLV is formatted as
   specified in [RFC5305].

                                             No. of octets
            +-----------------------------+
            | Type (20)                   |     1
            +-----------------------------+
            | Length (multiple of 4)      |     1
            +-----------------------------+
            | Discriminator Value(s)      |     4/Discriminator
            :                             :
            +-----------------------------+
            Figure 1: S-BFD Discriminators Sub-TLV for ISIS


   Inclusion of the S-BFD Discriminators sub-TLV in a Router Capability
   TLV is optional.  Multiple S-BFD Discriminators sub-TLVs MAY be
   advertised by an IS.

   [RFC7884] defines the following TLVs to encode the S-BFD
   Discriminators information.  The format of the S-BFD Discriminator
   TLV is 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
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |              Type             |             Length            |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                         Discriminator 1                       |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                    Discriminator 2 (Optional)                 |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                               ...                             |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                    Discriminator n (Optional)                 |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
               Figure 2: S-BFD Discriminators TLV for OSPF


   Type - S-BFD Discriminator TLV Type (11)



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   Length - Total length of the discriminator (Value field) in octets,
   not including the optional padding.  The Length is a multiple of 4
   octets, and consequently specifies how many Discriminators are
   included in the TLV.

   Value - S-BFD network target discriminator value or values.

   Routers that do not recognize the S-BFD Discriminator TLV Type MUST
   ignore the TLV.  S-BFD discriminator is associated with the BFD
   Target Identifier type, which allows de-multiplexing to a specific
   task or service.

   These TLVs are mapped to BGP-LS attribute TLVs in the following way.
   The new information in the Link-State NLRIs and attributes is encoded
   in Type/Length/Value triplets.

      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            |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     //                        Value (variable)                     //
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
                     Figure 3: BGP-LS TLV format


   The 2 octet Type field values are defined in Table 1.  The next 2
   octet Length field encodes length of the rest of the TLV.  The Value
   portion of the TLV is variable and is equal to the corresponding
   Value portion of the TLV defined in [RFC7883] and [RFC7884].

   The following 'Node Attribute' TLVs are defined:

   +---------------+-------------------------+----------+--------------+
   |    TLV Code   | Description             | Length   |    ISIS/OSPF |
   |     Point     |                         |          |  TLV/Sub-TLV |
   +---------------+-------------------------+----------+--------------+
   |      TBD      | S-BFD Discriminators    | variable |          TBD |
   |      ...      | ...                     | ...      |          ... |
   +---------------+-------------------------+----------+--------------+
                           Table 1: Node Attribute TLVs


   These TLVs can ONLY be added to the Node Attribute associated with
   the Node NLRI that originates the corresponding S-BFD Discriminator
   TLV.





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5.  Operations

   Existing BGP and BGP-LS operational procedures apply.  No new
   operation procedures are defined in this document.

6.  IANA Considerations

   This document requests assigning code-points from the registry for
   BGP-LS attribute TLVs based on table Table 1.

7.  Security Considerations

   Procedures and protocol extensions defined in this document do not
   affect the BGP security model.  See [RFC6952] for details.

8.  Acknowledgements

   The authors would like to thank Nan Wu for his contributions to this
   work.

9.  References

9.1.  Normative References

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

9.2.  Informative References

   [I-D.ietf-mpls-seamless-mpls]
              Leymann, N., Decraene, B., Filsfils, C., Konstantynowicz,
              M., and D. Steinberg, "Seamless MPLS Architecture", draft-
              ietf-mpls-seamless-mpls-07 (work in progress), June 2014.

   [RFC4971]  Vasseur, JP., Ed., Shen, N., Ed., and R. Aggarwal, Ed.,
              "Intermediate System to Intermediate System (IS-IS)
              Extensions for Advertising Router Information", RFC 4971,
              DOI 10.17487/RFC4971, July 2007,
              <http://www.rfc-editor.org/info/rfc4971>.

   [RFC5305]  Li, T. and H. Smit, "IS-IS Extensions for Traffic
              Engineering", RFC 5305, DOI 10.17487/RFC5305, October
              2008, <http://www.rfc-editor.org/info/rfc5305>.






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   [RFC5880]  Katz, D. and D. Ward, "Bidirectional Forwarding Detection
              (BFD)", RFC 5880, DOI 10.17487/RFC5880, June 2010,
              <http://www.rfc-editor.org/info/rfc5880>.

   [RFC6952]  Jethanandani, M., Patel, K., and L. Zheng, "Analysis of
              BGP, LDP, PCEP, and MSDP Issues According to the Keying
              and Authentication for Routing Protocols (KARP) Design
              Guide", RFC 6952, DOI 10.17487/RFC6952, May 2013,
              <http://www.rfc-editor.org/info/rfc6952>.

   [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,
              <http://www.rfc-editor.org/info/rfc7752>.

   [RFC7880]  Pignataro, C., Ward, D., Akiya, N., Bhatia, M., and S.
              Pallagatti, "Seamless Bidirectional Forwarding Detection
              (S-BFD)", RFC 7880, DOI 10.17487/RFC7880, July 2016,
              <http://www.rfc-editor.org/info/rfc7880>.

   [RFC7883]  Ginsberg, L., Akiya, N., and M. Chen, "Advertising
              Seamless Bidirectional Forwarding Detection (S-BFD)
              Discriminators in IS-IS", RFC 7883, DOI 10.17487/RFC7883,
              July 2016, <http://www.rfc-editor.org/info/rfc7883>.

   [RFC7884]  Pignataro, C., Bhatia, M., Aldrin, S., and T. Ranganath,
              "OSPF Extensions to Advertise Seamless Bidirectional
              Forwarding Detection (S-BFD) Target Discriminators",
              RFC 7884, DOI 10.17487/RFC7884, July 2016,
              <http://www.rfc-editor.org/info/rfc7884>.

Authors' Addresses

   Zhenbin Li
   Huawei Technologies
   Huawei Bld., No.156 Beiqing Rd.
   Beijing  100095
   China

   Email: lizhenbin@huawei.com










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   Sam Aldrin
   Huawei Technologies
   2330 Central Expressway
   Santa Clara  CA 95051

   Email: sam.aldrin@huawei.com


   Jeff Tantsura
   Ericsson
   200 Holger Way
   San Jose  CA 95134
   USA

   Email: jeff.tantsura@ericsson.com


   Greg Mirsky
   Ericsson
   300 Holger Way
   San Jose  CA 95134
   USA

   Email: gregory.mirsky@ericsson.com


   Shunwan Zhuang
   Huawei Technologies
   Huawei Bld., No.156 Beiqing Rd.
   Beijing  100095
   China

   Email: zhuangshunwan@huawei.com


















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