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Versions: 00                                                            
Network Working Group                                            F. Duan
Internet-Draft                                                    J. Xie
Updates: 6514 (if approved)                          Huawei Technologies
Intended status: Standards Track                         23 October 2021
Expires: 26 April 2022


    BGP MVPN in IPv6 Infrastructure Networks: Problems and Solution
                               Approaches
                  draft-duan-bess-mvpn-ipv6-infras-00

Abstract

   MVPN deployment faces some problems while used in provider's IPv6
   infrastructure networks.  This document describes these problems, and
   the solutions to solve these problems.

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.

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 26 April 2022.

Copyright Notice

   Copyright (c) 2021 IETF Trust and the persons identified as the
   document authors.  All rights reserved.





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   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 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 . . . . . . . . . . . . . . . . . . . . . . . . .   2
   3.  Problems and Solutions  . . . . . . . . . . . . . . . . . . .   2
     3.1.  Problems  . . . . . . . . . . . . . . . . . . . . . . . .   2
     3.2.  Modification of C-Multicast route NLRI  . . . . . . . . .   4
     3.3.  Route reflection control  . . . . . . . . . . . . . . . .   5
   4.  Security Considerations . . . . . . . . . . . . . . . . . . .   5
   5.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   6
   6.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   6
   7.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   6
     7.1.  Normative References  . . . . . . . . . . . . . . . . . .   6
     7.2.  Informative References  . . . . . . . . . . . . . . . . .   6
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   7

1.  Introduction

   BGP MVPN procedure is defined in [RFC6514].  As a mature MVPN
   technology, it has been accepted by most operators and vendors.  In
   [RFC6515] , BGP MVPN is updated for IPv6 infrastructure networks.
   However, the deployment of BGP MVPN in IPv6 network still faces some
   problems.  This document describes these problems, and the solutions
   to solve these problems.

2.  Terminology

   Readers of this document are assumed to be familiar with the
   terminology and concepts of the documents listed as Normative
   References.

3.  Problems and Solutions


3.1.  Problems

   In [RFC6514], the following processes are not suitable if IPv6
   infrastructure addresses are used in provider's netwroks:




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   1.  In paragraph 7 of section 11.1.3, it described that "To support
       non-segmented inter-AS tunnels, the Source AS field in the
       C-multicast route is set to value of the Originating Router's IP
       Address field of the found Intra-AS I-PMSI A-D route".  In NLRI
       of C-multicast route, Source AS field is 4 octs length, while the
       Originating Router's IP Address field of Intra-AS I-PMSI A-D
       route is 16 octs length in provider's IPv6 neworks.

   2.  In paragraph 2 of section 11.2, it described that "To support
       non-segmented inter-AS tunnels, instead of matching the RD and
       Source AS carried in the C-multicast route against the RD and
       Source AS of an Inter-AS I-PMSI A-D route, the ASBR should match
       it against the RD and the Originating Router's IP Address of the
       Intra-AS I-PMSI A-D routes".  Source AS field in NLRI of
       C-multicast route cannot be translated to the Originating
       Router's IP Address of the Intra-AS I-PMSI A-D routes in
       provider's IPv6 neworks, because of the mismatch of thier feild
       length.

   In [RFC7716], zero RD is introduced in BGP MVPN NLRIs to enable
   Global Table Multicast service in provider's netwroks.  In IPv6
   infrastructure networks, Leaf PEs cannot send two distinct
   C-multicast route to two individual upstream root PEs for selctive
   forwarding, because the RD of the two roots is the same.

   In the process of evolution to IPv6, IPv4 and IPv6 infrastructure
   addresses will coexist in the provider's network.  The following
   figure is an example of BGP MVPN evolution to IPv6.

    +-----------+           +---+     +---+           +-----------+
    | +-------+ |           |   |     |   |           | +-------+ |
    | | O-MVRF| |=BGP Peer4=|   |     |   |=BGP Peer4=| | O-MVRF| |
    | +-------+ |           |   |     |   |           | +-------+ |
    |           |           |   |     |   |           |           |
    |    PE1    |           |RR1| ... |RRn|           |    PE2    |
    |           |           |   |     |   |           |           |
    | +-------+ |           |   |     |   |           | +-------+ |
    | | N-MVRF| |=BGP Peer6=|   |     |   |=BGP Peer6=| | N-MVRF| |
    | +-------+ |           |   |     |   |           | +-------+ |
    +-----------+           +---+     +---+           +-----------+
    O-MVRF = Old Multicast VRF using IPv4 infrastructure addresses
    N-MVRF = New Multicast VRF using IPv6 infrastructure addresses

            Figure 1: BGP MVPN Evolution to IPv6 Infrastructure

   During the evolution process, IPv4 and IPv6 parallel BGP sessions are
   established between Provider Edge routers and Reflctor routers, if
   the BGP MVPN route send to all IPv4 and IPv6 BGP peer without any



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   control, the number of the PATHs of these routes will be doubled with
   each reflection while BGP [ADD-PATH] procedure is enabled on Reflctor
   routers.

3.2.  Modification of C-Multicast route NLRI

   To support non-segmented inter-AS tunnels in IPv6 infrastructure
   network, the C-Multicast route NLRI is redifined as following:

         +-----------------------------------+
         |      RD   (8 octets)              |
         +-----------------------------------+
         |   Root Distinguisher (4 octets)   |
         +-----------------------------------+
         | Multicast Source Length (1 octet) |
         +-----------------------------------+
         |   Multicast Source (variable)     |
         +-----------------------------------+
         |  Multicast Group Length (1 octet) |
         +-----------------------------------+
         |  Multicast Group   (variable)     |
         +-----------------------------------+

   In the above figure, the Root Distinguisher field replaces the Source
   As field defined in [RFC6514].  When constructing a C-Multicast
   route, leaf PE follows the following specification:

   1.  If the Originating Router's IP Address field of the found Intra-
       AS I-PMSI A-D route is an IPv4 address, the Root Distinguisher
       field MUST be treated as Source AS field and section 11.1.3 of
       [RFC6514] MUST be followed.

   2.  If the Originating Router's IP Address field of the found Intra-
       AS I-PMSI A-D route is an IPv6 address and the root PE and leaf
       PE are in the same AS, the Root Distinguisher field MUST be
       treated as Source AS field and section 11.1.3 of [RFC6514] MUST
       be followed.

   3.  If the Originating Router's IP Address field of the found Intra-
       AS I-PMSI A-D route is an IPv6 address and the root PE and leaf
       PE are in the different ASes, a four octs distinct value MUST be
       assigned by leaf PE for each root PE, the Root Distinguisher
       feild in C-Multicast NLRI is filled with this value and a
       distinct C-multicast route will be send to individual upstream
       root PE.






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   When receiving a C-Multicast route from E-BGP neighbours, the ASBR
   checks whether an IPv6 VRF Route Import Extended Community is include
   in this route and takes following actions:

   1.  If the IPv6 VRF Route Import Extended Community does not exist in
       the C-Multicast route, the ASBR treats the Root Distinguisher
       field as Source AS field and follows the description in section
       11.2 of [RFC6514].

   2.  If the IPv6 VRF Route Import Extended Community does exist in the
       C-Multicast route, the ASBR match the IPv6 address carried in
       this extended community and the RD in C-Multicast route NLRI
       against the Originating Router's IP Address and the RD of the
       Intra-AS I-PMSI A-D routes.  If the corresponding Intra-AS I-PMSI
       A-D route exists, the ASBR propagates the C-Multicast route in
       its local AS.

3.3.  Route reflection control

   To reduce BGP MVPN routes in Parallel IPv4 and IPv6 BGP sessions
   networks, the following actions should be taken by sender PEs:

   1.  For Intra-AS I-PMSI A-D Route, S-PMSI A-D Route and Leaf A-D
       Route, if the Originating Router's IP Address feild in the route
       is filled with an IPv6 address, it is sent to the IPv6 BGP
       neighbors; otherwise, it is sent to the IPv4 BGP neighbors.

   2.  For Inter-AS I-PMSI A-D Route and Source Active A-D Route, it is
       sent to both IPv6 BGP neighbors and IPv4 BGP neighbors.

   3.  For C-Multicast Route, If the IPv6 VRF Route Import Extended
       Community exists in the route, it is sent to the IPv6 BGP
       neighbors; otherwise, it is sent to the IPv4 BGP neighbors.

   In the reflector routers, the part of routes which are received from
   IPv6 BGP neighbors will be reflected to other IPv6 BGP neighbors and
   the other part of routes which are received from IPv4 BGP neighbors
   will be reflected to other IPv4 BGP neighbors.

4.  Security Considerations

   This document introduces no new security considerations beyond those
   already specified in [RFC6514] and [RFC6515].








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5.  IANA Considerations

   This document contains no actions for IANA.


6.  Acknowledgements

   Your name here


7.  References

7.1.  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>.

   [RFC6513]  Rosen, E., Ed. and R. Aggarwal, Ed., "Multicast in MPLS/
              BGP IP VPNs", RFC 6513, DOI 10.17487/RFC6513, February
              2012, <https://www.rfc-editor.org/info/rfc6513>.

   [RFC6514]  Aggarwal, R., Rosen, E., Morin, T., and Y. Rekhter, "BGP
              Encodings and Procedures for Multicast in MPLS/BGP IP
              VPNs", RFC 6514, DOI 10.17487/RFC6514, February 2012,
              <https://www.rfc-editor.org/info/rfc6514>.

   [RFC6515]  Aggarwal, R. and E. Rosen, "IPv4 and IPv6 Infrastructure
              Addresses in BGP Updates for Multicast VPN", RFC 6515,
              DOI 10.17487/RFC6515, February 2012,
              <https://www.rfc-editor.org/info/rfc6515>.

   [RFC7716]  Zhang, J., Giuliano, L., Rosen, E., Ed., Subramanian, K.,
              and D. Pacella, "Global Table Multicast with BGP Multicast
              VPN (BGP-MVPN) Procedures", RFC 7716,
              DOI 10.17487/RFC7716, December 2015,
              <https://www.rfc-editor.org/info/rfc7716>.

   [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>.

7.2.  Informative References

   [I-D.ietf-idr-add-paths]
              Walton, D., Retana, A., Chen, E., and J. Scudder,
              "Advertisement of Multiple Paths in BGP", Work in



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              Progress, Internet-Draft, draft-ietf-idr-add-paths-15, 23
              May 2016, <https://www.ietf.org/archive/id/draft-ietf-idr-
              add-paths-15.txt>.

Authors' Addresses

   Fanghong Duan
   Huawei Technologies

   Email: duanfanghong@huawei.com


   Jingrong Xie
   Huawei Technologies

   Email: xiejingrong@huawei.com



































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