BGP Extended Community for Identifying the Target Nodes
draft-dong-idr-node-target-ext-comm-04

Document Type Active Internet-Draft (individual)
Authors Jie Dong  , Shunwan Zhuang  , Gunter Van de Velde 
Last updated 2021-07-12
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Network Working Group                                            J. Dong
Internet-Draft                                                 S. Zhuang
Intended status: Standards Track                     Huawei Technologies
Expires: January 13, 2022                                G. Van de Velde
                                                                   Nokia
                                                           July 12, 2021

        BGP Extended Community for Identifying the Target Nodes
                 draft-dong-idr-node-target-ext-comm-04

Abstract

   BGP has been used to distribute different types of routing and policy
   information.  In some cases, the information distributed may be only
   intended for one or a particular group of BGP nodes in the network.
   Currently BGP does not have a generic mechanism of designating the
   target nodes of the routing information.  This document defines a new
   type of BGP Extended Community called "Node Target".  The mechanism
   of using the Node Target Extended Community to steer BGP route
   distribution to particular BGP nodes is specified.

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
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   Internet-Drafts are draft documents valid for a maximum of six months
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   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on January 13, 2022.

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Copyright Notice

   Copyright (c) 2021 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
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   (https://trustee.ietf.org/license-info) in effect on the date of
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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
   2.  Node Target Extended Communities  . . . . . . . . . . . . . .   3
   3.  Procedures  . . . . . . . . . . . . . . . . . . . . . . . . .   4
   4.  Compatibility Considerations  . . . . . . . . . . . . . . . .   5
   5.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   5
   6.  Security Considerations . . . . . . . . . . . . . . . . . . .   5
   7.  Contributors  . . . . . . . . . . . . . . . . . . . . . . . .   5
   8.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   6
   9.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   6
     9.1.  Normative References  . . . . . . . . . . . . . . . . . .   6
     9.2.  Informative References  . . . . . . . . . . . . . . . . .   6
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   7

1.  Introduction

   BGP [RFC4271] has been used to distribute different types of routing
   and policy information.  In some cases, the information distributed
   may be only intended for one or a particular group receiving BGP
   nodes in the network.  One typical use case is the distribution of
   BGP Flow Spec [RFC8955] [RFC8956] rules only to a particular group of
   BGP nodes.  Such a targeting mechanism is considered useful that it
   can save the resources on nodes which do not need that information.

   Currently BGP does not have a generic mechanism of designating the
   set of nodes to which the information is to be distributed.  Route
   Target (RT) as defined in [RFC4364] was designed for the matching of
   VPN routes into the target VPN Routing and Forwarding tables (VRFs)
   on PE nodes.  Although [I-D.ietf-idr-segment-routing-te-policy]
   introduces the mechanism of steering the SR policy information to the
   target head end node based on RT, it is only defined for the SR
   Policy Address Family.  Although it is possible to reuse RTs to

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   control the distribution of non-VPN information to one or a group of
   receiving nodes, such mechanism is not applicable when the
   information to be distributed is VPN-specific and is advertised with
   a set of RTs for the VRF matching.  In that case, the matching of any
   of the VPN RTs in the Update will result in the information eligible
   for installation, regardless of whether the RTs representing the
   target nodes are matched or not.  Thus a mechanism which is
   independent from the control of VPN route to VRF distribution is
   needed.

   Another possible approach is to configure, on each router, a
   community and the corresponding policies to match the community to
   determine whether to accept the received routes.  Such mechanism
   relies on manual configuration thus is considered error-prone.  It is
   preferable by some operators that an automatic approach can be
   provided, which would make the operation much easier.

   This document defines a new type of BGP Extended Community called
   "Node Target".  The mechanism of using the Node Target extended
   community to steer BGP route distribution to particular BGP nodes is
   also specified.

2.  Node Target Extended Communities

   This section defines a new BGP Extended Community [RFC4360] called
   "Node Target Extended Community".  It can be a transitive extended
   community with the high-order octect of the type set to 0x01, or a
   non-transitive extended community with the high-order octect type set
   to 0x41.  The sub-type of the Node Target Extended Community is TBA.

   The format of Node Target Extended Community is shown in Figure 1.

       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
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |  0x01 or 0x41 | Sub-Type(TBA) |    Target BGP Identifier      |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      | Target BGP Identifier (cont.) |           Reserved            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

               Figure 1. Node Target extended community

   Where:

   Target BGP Identifier (4 octets): The BGP Identifier of a target
   node.  It is a 4-octet, unsigned, non-zero integer as defined in
   [RFC6286].

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   Reserved field (2 octets): Reserved for future use, MUST be set to
   zero on transmission and ignored on receipt.

   One or more Node Target extended communities MAY be carried in an
   Update message to designate a group of target BGP nodes.

3.  Procedures

   In this section, the mechanism for intra-domain scenario is
   described, the mechanism for inter-domain scenario is for further
   study.  The domain here refers to an administrative domain, which may
   consists of one or multiple ASes managed by a single operator.

   When a network controller or BGP speaker plans to advertise some BGP
   routing or policy information only to one or a group of BGP nodes in
   the network, it MUST put the BGP Identifier of each target node into
   the Node Target extended communities, and attach the Node Target
   extended communities to the routes or policies to be advertised.

   When a BGP speaker receives a BGP Update which contains one or more
   Node Target extended communities, it MUST check the target BGP
   Identifiers carried in the Node Target extended communities of the
   Update.

   o  If the target BGP Identifier in any of the Node Target extended
      community matches with the local BGP Identifier, this node is one
      of the target nodes of the Update, the information in the Update
      is eligible to be kept and installed on this node.

      *  If this node is a Route Reflector, and in the Update there is
         one or more Node Target extended communities which contains
         non-local BGP Identifiers, information in the Update are
         eligible be reflected to its peers according to the rules
         defined in [RFC4456].  Depends on a configurable policy, the RR
         MAY check the BGP Identifiers of its peers to determine the set
         of peers which are the target nodes of the Update, and only
         reflect the information in the Update to the matched BGP peers.

      *  If this node is an Autonomous System Border Router (ASBR), and
         the BGP Identifiers of one or more of its EBGP peers match with
         the Node Target extended communities in the Update, information
         in the Update is eligible to be advertised to the matched EBGP
         peers.

   o  If the target BGP Identifier in any of the Node target extended
      community does not match with the local BGP Identifier, this node
      is not the target node of Update, the information in the Update is
      not eligible to be installed on this node.

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      *  If this node is a Route Reflector, information in the Update is
         eligible to be reflected to its peers according to the rules
         defined in [RFC4456].  Depends on a configurable policy, the RR
         MAY check the BGP Identifiers of its peers to determine the set
         of peers which are the target nodes of the Update, and only
         reflect the information in the Update to the matched BGP peers.

4.  Compatibility Considerations

   The Node Target extended community introduced in this document can be
   deployed incrementally in the network.  For BGP speakers which
   understand the Node Target extended community, it is used to
   determine whether the nodes are the target nodes of the Update.  For
   BGP speakers which do not understand the Node Target extended
   community, it will be ignored and the information in the Update will
   be processed and advertised based on normal BGP procedure.  Although
   this could ensure that the target nodes can always obtain the
   information needed, this may result in unnecessary state maintained
   on legacy BGP speakers.  And if the information advertised is the
   Flow Spec rules, the legacy BGP speakers may install unnecessary
   flowspec rules, this may have impact on traffic which matches such
   rules, thus may result in unexpected traffic steering or filtering
   behaviors on such nodes.  This may be mitigated by setting
   appropriate routing policies on the legacy BGP nodes.

5.  IANA Considerations

   This document requests that IANA assigns one new sub-type for "Node
   Target Extended Community" from the "Transitive IPv4-Address-Specific
   Extended Community" registry of the "BGP Eextended Communities"
   registry.

   This document requests that IANA assigns the same sub-type for "Node
   Target Extended Community" from the "Non-Transitive IPv4-Address-
   Specific Extended Community" registry of the "BGP Eextended
   Communities" registry.

6.  Security Considerations

   TBD

7.  Contributors

   Haibo Wang
   Email: rainsword.wang@huawei.com

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8.  Acknowledgements

   The authors would like to thank Zhenbin Li, Ercin Torun, Jeff Haas,
   Robert Raszuk and John Scudder for the review and discussion of this
   document.

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,
              <https://www.rfc-editor.org/info/rfc2119>.

   [RFC4271]  Rekhter, Y., Ed., Li, T., Ed., and S. Hares, Ed., "A
              Border Gateway Protocol 4 (BGP-4)", RFC 4271,
              DOI 10.17487/RFC4271, January 2006,
              <https://www.rfc-editor.org/info/rfc4271>.

   [RFC4360]  Sangli, S., Tappan, D., and Y. Rekhter, "BGP Extended
              Communities Attribute", RFC 4360, DOI 10.17487/RFC4360,
              February 2006, <https://www.rfc-editor.org/info/rfc4360>.

   [RFC4456]  Bates, T., Chen, E., and R. Chandra, "BGP Route
              Reflection: An Alternative to Full Mesh Internal BGP
              (IBGP)", RFC 4456, DOI 10.17487/RFC4456, April 2006,
              <https://www.rfc-editor.org/info/rfc4456>.

9.2.  Informative References

   [I-D.ietf-idr-segment-routing-te-policy]
              Previdi, S., Filsfils, C., Talaulikar, K., Mattes, P.,
              Rosen, E., Jain, D., and S. Lin, "Advertising Segment
              Routing Policies in BGP", draft-ietf-idr-segment-routing-
              te-policy-11 (work in progress), November 2020.

   [RFC4364]  Rosen, E. and Y. Rekhter, "BGP/MPLS IP Virtual Private
              Networks (VPNs)", RFC 4364, DOI 10.17487/RFC4364, February
              2006, <https://www.rfc-editor.org/info/rfc4364>.

   [RFC5575]  Marques, P., Sheth, N., Raszuk, R., Greene, B., Mauch, J.,
              and D. McPherson, "Dissemination of Flow Specification
              Rules", RFC 5575, DOI 10.17487/RFC5575, August 2009,
              <https://www.rfc-editor.org/info/rfc5575>.

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   [RFC6286]  Chen, E. and J. Yuan, "Autonomous-System-Wide Unique BGP
              Identifier for BGP-4", RFC 6286, DOI 10.17487/RFC6286,
              June 2011, <https://www.rfc-editor.org/info/rfc6286>.

   [RFC8955]  Loibl, C., Hares, S., Raszuk, R., McPherson, D., and M.
              Bacher, "Dissemination of Flow Specification Rules",
              RFC 8955, DOI 10.17487/RFC8955, December 2020,
              <https://www.rfc-editor.org/info/rfc8955>.

   [RFC8956]  Loibl, C., Ed., Raszuk, R., Ed., and S. Hares, Ed.,
              "Dissemination of Flow Specification Rules for IPv6",
              RFC 8956, DOI 10.17487/RFC8956, December 2020,
              <https://www.rfc-editor.org/info/rfc8956>.

Authors' Addresses

   Jie Dong
   Huawei Technologies
   Huawei Campus, No. 156 Beiqing Rd.
   Beijing  100095
   China

   Email: jie.dong@huawei.com

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

   Email: zhuangshunwan@huawei.com

   Gunter Van de Velde
   Nokia
   Antwerp
   BE

   Email: gunter.van_de_velde@nokia.com

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