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Versions: (draft-geng-pim-bier-sr-multicast-deployment) 00

Network Working Group                                            L. Geng
Internet-Draft                                              China Mobile
Intended status: Standards Track                                  J. Xie
Expires: January 5, 2020                             Huawei Technologies
                                                              M. McBride
                                                               Futurewei
                                                                  G. Yan
                                                     Huawei Technologies
                                                            July 4, 2019


             Inter-Domain Multicast Deployment using BIERv6
                  draft-geng-bier-ipv6-inter-domain-00

Abstract

   Bit Index Explicit Replication IPv6 encapsulation (BIERv6) introduces
   an approach to use IPv6 extension header to carry BIER header with
   IPv6 unicast address as destination address.  It provides the ability
   to replicate a packet from one router to another router in a
   different domain as well as in the same domain.  This document
   introduces the techniques for multicast deployment across multiple
   domains using BIERv6, and demonstrate how BIERv6 is beneficial for
   such deployment.

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 [RFC2119] and
   [RFC8174].

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 5, 2020.



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Copyright Notice

   Copyright (c) 2019 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 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.  Inter-domain Multicast Overview . . . . . . . . . . . . . . .   3
   4.  Inter-domain Multicast Deployment using BIERv6  . . . . . . .   3
     4.1.  Hierarchical Multicast  . . . . . . . . . . . . . . . . .   3
     4.2.  Peering Multicast . . . . . . . . . . . . . . . . . . . .   6
   5.  Security Considerations . . . . . . . . . . . . . . . . . . .   8
   6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   8
   7.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   8
   8.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   8
     8.1.  Normative References  . . . . . . . . . . . . . . . . . .   8
     8.2.  Informative References  . . . . . . . . . . . . . . . . .   9
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  10

1.  Introduction

   Bit Index Explicit Replication [RFC8296] IPv6 encapsulation (BIERv6)
   described in [I-D.xie-bier-ipv6-encapsulation] introduces an approach
   to use IPv6 extension header to carry BIER header.  One BIERv6
   option, using IPv6 unicast address as destination address provides
   the ability to replicate a packet from one router to another router
   in a different domain as well as in the same domain.  This document
   introduces the techniques for multicast deployment across multiple
   domains using BIERv6, and demonstrates how BIERv6 is beneficial for
   such deployment.

2.  Terminology

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



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3.  Inter-domain Multicast Overview

   It is common to deploy multicast services across multiple domains.

   One typical scenario for this type of deployment is in a service-
   provider network for MVPN service as described in
   [I-D.ietf-bier-ipv6-requirements].  Service provider network tends to
   be very heterogeneous with full-mesh backbone network, and metro
   networks with fabric for dense area coverage or ring-shaped for
   sparse area coverage.  The backbone network and metro networks are
   autonomous systems interconnected by border routers (BRs).
   Multicast-based delivery of video need to be set up from a source
   router on the backbone to each of the boundary routers of each metro
   network.

   This scenario may have some variant.  For example, multicast source
   router is a Top of Rack (TOR) switch in a service provider data
   center(SPDC) connected to backbone with data center gateway(s) (DC-
   GW), and multicast receiver is the home broadband subscribers
   connected to boundary routers (e.g.  BNG) of each metro network.
   Operators may want to set up multicast-based delivery from TOR to
   BNGs seamlessly without segmentation or stitching on DC-GW(s) or
   BR(s).

   It is described as hierachical multicast in this document.

   Another typical scenario for inter-domain multicast deployment is in
   peering network as described in [RFC8313] to set up multicast-based
   delivery of content across inter-domain peering points.

   This scenario may have some variant.  For example, interconnected
   content delivery networks (CDNs) (described in [RFC6770]) owned by
   Network Service Providers (NSPs) or Enterprise Service Providers may
   need to deliver multicast from one to others.

   It is described as peering multicast in this document.

4.  Inter-domain Multicast Deployment using BIERv6

4.1.  Hierarchical Multicast

   Following is an example of hierarchical deployment of multicast.









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                                             +---------------------+
                                             |  Metro 2 (AS 64002) |
                                             | +-----+    +------+ |
                                       +-------| BR2 |    | PE2x |---RCV
                                     /       | +-----+    +------+ |
                                   /         +---------------------+
       +---------------------+   /             Bfr-id 1 to 256
       | Backbone (AS 64001) | /
       | +------+    +-----+ /
   SRC---| PE1x |    | BR1 | |
       | +------+    +-----+ \
       +---------------------+ \                Bfr-id 257 to 512
            |                    \           +---------------------+
            |                      \         |  Metro 3 (AS 64003) |
            |                        \       | +-----+    +------+ |
            |                          +-------| BR3 |    | PE3x |---RCV
            |                                | +-----+    +------+ |
            |                                +---------------------+
            |                                                 |
            |<----------------- BIERv6 Domain --------------->|

    BR = Border Router
    SRC = Multicast Source
    RCV = Multicast Receiver

               Figure 1: Inter-Domain Hierarchical Multicast

   Multicast source is connected to PE1x, and multicast receivers are
   connected to PE2x and PE3x.

   PE1x, PE2x, PE3x is located in Backbone (AS 64001), Metro 2 (AS
   64002), and Metro 3 (AS 64003) respectively, and BR1, BR2, BR3 is
   boarder of these three domains.  They belong to a single
   administrative domain.

   IGP underlay for BIERv6 is deployed in Metro2, Metro3 respectively.
   The bfr-ids in Metro2 and Metro 3 should be divided rationally.

   PE1x, PE2x, PE3x uses 2001::E1, 2001::E2, 2001::E3 as IPv6 BFR-prefix
   (and End.BIER function) respectively.

   BR1, BR2, BR3 uses 2001::B1, 2001::B2, 2001::B3 as IPv6 BFR-prefix
   (and End.BIER function) respectively.

   All of them use the Non-MPLS static BSL-SD-SI BIFT encoding method
   described in [I-D.ietf-bier-non-mpls-bift-encoding] as the auto-
   generation method.




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   On BR1, static configuration can be used to construct inter-domain
   BIERv6 forwarding table.

       bier sub-domain 6 ipv6-underlay
         bfr-prefix 2001::B1
         bfr-id 0
         encapsulation ipv6 bsl 256 max-si 2
         static-bift
           nexthop 2001::B2 bfr-id 1 to 256
           nexthop 2001::B3 bfr-id 257 to 512

   Accordingly, the following BIFTs will be constructed:

       BIFT correspond to SD<6>/BSL<256>/SI<0>
         (neighbor = 2001::B2, F-BM = ffff....ffff)
       BIFT correspond to SD<6>/BSL<256>/SI<1>
         (neighbor = 2001::B3, F-BM = ffff....ffff)

   On PE1x, static configuration can be used to construct inter-domain
   BIERv6 forwarding table.

       bier sub-domain 6 ipv6-underlay
         bfr-prefix 2001::E1
         bfr-id 0
         encapsulation ipv6 bsl 256 max-si 2
         static-bift
           nexthop 2001::B1 bfr-id 1 to 512

   Accordingly, the following BIFTs will be constructed:

       BIFT correspond to SD<6>/BSL<256>/SI<0>
         (neighbor = 2001::B1, F-BM = ffff....ffff)
       BIFT correspond to SD<6>/BSL<256>/SI<1>
         (neighbor = 2001::B1, F-BM = ffff....ffff)

   Use of BGP as inter-domain underlay protocol to advertise the BIER
   information from BR2 or BR2 to BR1, or from BR1 to PE1x is outside
   the scope of this document.

   On each domain, two redundant border routers may be deployed, and
   anycase IPv6 address can be used on each pair of BRs as BFR-prefix.

   Inter-Domain BIER will converge normally when unicast converge and
   the BIFT will be reconstructed accordingly.

   For multicast overlay layer, there are no extensions needed.  MVPN is
   deployed on PE1x, PE2x and PE3x using sub-domain 6 and bsl 256
   without segmentation on border router(s).



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   Note: Use of the IPv6 address configured on PE1 to identify an MVPN
   instance can eliminate the need for BFR-id configuration on PE1x,
   which otherwise has to be configured from the space of a sub-domain.

4.2.  Peering Multicast

   Following is an example of peering deployment of multicast.

                                             +---------------------+
                                             |    AD-2 (AS 65002)  |
                                   +---+     | +-----+    +------+ |
                                 /   I   \   | | BR2 |    | PE2x |---RCV
              (color 1)         (    N    )  | +-----+    +------+ |
            Bfr-id 1 to 256     (    T    )  +---------------------+
       +---------------------+  (    E    )       Bfr-id 1 to 512
       |    AD-1 (AS 65001)  |  (    R    )         (color 2)
       | +------+    +-----+ |  (    C    )
   SRC---| PE1x |    | BR1 | |  (    O    )
       | +------+    +-----+ |  (    N    )
       | +------+            |  (    N    )
   RCV---| PE1y |            |  (    E    )
       | +------+            |  (    C    )         (color 3)
       +---------------------+  (    T    )       Bfr-id 1 to 256
                                (    I    )  +---------------------+
                                (    O    )  |    AD-3 (AS 65003)  |
                                 \   N   /   | +-----+    +------+ |
                                   +---+     | | BR3 |    | PE3x |---RCV
                                             | +-----+    +------+ |
                                             +---------------------+
    AD = Administrative Domain (independent autonomous system)
    BR = Border Router
    SRC = Multicast Source
    RCV = Multicast Receiver

                 Figure 2: Inter-Domain Peering Multicast

   Each Administrative Domain AD-1, AD-2 or AD-3 is configured a unique
   color.  Color 1, 2, 3 are used in this example.

   For routing underlay layer, the ingress router uses IGP protocol (IS-
   IS as example in this document) for the domain it belongs to, and
   uses static configuration for the domain it doesn't belong to.

   Below is an example of routing underlay configuration on PE1x:







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       # PE1x routing underlay layer configuration
       bier sub-domain 6 ipv6-underlay
         bfr-prefix 2001::E1
         bfr-id 1
         encapsulation ipv6 bsl 256 max-si 1
         color 1 protocol isis
         color 2 static-bift
           next-hop 2001::B2 bfr-id 1 to 512
         color 3 static-bift
           next-hop 2001::B3 bfr-id 1 to 256

   The following lists the BIFT that will be constructed on PE1x:

      BIFT corresponding  to SD<6>/BSL<256>/SI<0> for color 1 ;;Ref1
      BIFT corresponding  to SD<6>/BSL<256>/SI<0> for color 2 ;;Ref2
      BIFT corresponding  to SD<6>/BSL<256>/SI<1> for color 2 ;;Ref3
      BIFT corresponding  to SD<6>/BSL<256>/SI<0> for color 3 ;;Ref4

   Ref1: BIFT constructed using IGP.

   Ref2: BIFT constructed using static configuration, with BR2 a multi-
   hop BFR neighbor of PE1x.

   Ref3: BIFT constructed using static configuration, with BR2 a multi-
   hop BFR neighbor of PE1x.

   Ref3: BIFT constructed using static configuration, with BR3 a multi-
   hop BFR neighbor of PE1x.

   For multicast overlay layer, the color extended community defined in
   [RFC5512] is carried in Leaf A-D route together with the PTA
   attribute.

   (1) PE in each domain gets the color it belongs to.  This can be done
   by configuration on each PE in each domain.

   (2) PE carries a color attribute in BGP-MVPN Leaf A-D route when
   advertising to Ingress PE as response to explicit-tracking initiated
   by the Ingress PE.  This can be done by configuration on MVPN
   deployment.  Refer to [I-D.xie-bier-ipv6-mvpn] for other attributes
   needed to be used.

   (3) The Ingress PE gets the Leaf A-D route, learns the BFERs of a
   color (representing a domain) interested in a multicast flow, and
   constructs the overlay forwarding table.  Below is an example of the
   overlay forwarding table on PE1x:





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     (VRF<X>, S<S1>, G<G1>)
       (Color<1>, SD<6>, BSL<256>, SI<0>, BitString<0001>) ;;Ref1
       (Color<2>, SD<6>, BSL<256>, SI<0>, BitString<0001>) ;;Ref2
       (Color<2>, SD<6>, BSL<256>, SI<1>, BitString<0001>) ;;Ref3
       (Color<3>, SD<6>, BSL<256>, SI<0>, BitString<0001>) ;;Ref4

   Ref1: packet will be replicated according to the BitString<0001> and
   the BIFT constructed using the IGP for SD<6>/BSL<256>/SI<0> for color
   1.

   Ref2: packet will be replicated according to the BitString<0001> and
   the BIFT constructed using the static-bift configuration for
   SD<6>/BSL<256>/SI<0> for color 2.

   Ref3: packet will be replicated according to the BitString<0001> and
   the BIFT constructed using the static-bift configuration for
   SD<6>/BSL<256>/SI<1> for color 2.

   Ref3: packet will be replicated according to the BitString<0001> and
   the BIFT constructed using the static-bift configuration for
   SD<6>/BSL<256>/SI<1> for color 3.

   Note: BFR-id configuration on PE1x is only necessary when PE1x will
   act as BFER, for example, there is multicast packet from PE2x to
   PE1x.  The BFR-ids in color 1, 2, 3 is independent on each other.

5.  Security Considerations

   The procedures of this document do not, in themselves, provide
   privacy, integrity, or authentication for the control plane or the
   data plane.

6.  IANA Considerations

   No IANA Allocation is required in this document.

7.  Acknowledgements

   TBD.

8.  References

8.1.  Normative References

   [I-D.ietf-bier-ipv6-requirements]
              McBride, M., Xie, J., Dhanaraj, S., and R. Asati, "BIER
              IPv6 Requirements", draft-ietf-bier-ipv6-requirements-00
              (work in progress), May 2019.



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   [I-D.ietf-bier-non-mpls-bift-encoding]
              Wijnands, I., Xu, X., and H. Bidgoli, "An Optional
              Encoding of the BIFT-id Field in the non-MPLS BIER
              Encapsulation", draft-ietf-bier-non-mpls-bift-encoding-01
              (work in progress), October 2018.

   [I-D.xie-bier-ipv6-encapsulation]
              Xie, J., Geng, L., McBride, M., Dhanaraj, S., Yan, G., and
              Y. Xia, "Encapsulation for BIER in Non-MPLS IPv6
              Networks", draft-xie-bier-ipv6-encapsulation-01 (work in
              progress), June 2019.

   [I-D.xie-bier-ipv6-mvpn]
              Xie, J., McBride, M., Dhanaraj, S., and L. Geng, "Use of
              BIER IPv6 Encapsulation (BIERv6) for Multicast VPN in IPv6
              networks", draft-xie-bier-ipv6-mvpn-01 (work in progress),
              July 2019.

   [RFC5512]  Mohapatra, P. and E. Rosen, "The BGP Encapsulation
              Subsequent Address Family Identifier (SAFI) and the BGP
              Tunnel Encapsulation Attribute", RFC 5512,
              DOI 10.17487/RFC5512, April 2009,
              <https://www.rfc-editor.org/info/rfc5512>.

   [RFC6770]  Bertrand, G., Ed., Stephan, E., Burbridge, T., Eardley,
              P., Ma, K., and G. Watson, "Use Cases for Content Delivery
              Network Interconnection", RFC 6770, DOI 10.17487/RFC6770,
              November 2012, <https://www.rfc-editor.org/info/rfc6770>.

   [RFC8279]  Wijnands, IJ., Ed., Rosen, E., Ed., Dolganow, A.,
              Przygienda, T., and S. Aldrin, "Multicast Using Bit Index
              Explicit Replication (BIER)", RFC 8279,
              DOI 10.17487/RFC8279, November 2017,
              <https://www.rfc-editor.org/info/rfc8279>.

   [RFC8313]  Tarapore, P., Ed., Sayko, R., Shepherd, G., Eckert, T.,
              Ed., and R. Krishnan, "Use of Multicast across Inter-
              domain Peering Points", BCP 213, RFC 8313,
              DOI 10.17487/RFC8313, January 2018,
              <https://www.rfc-editor.org/info/rfc8313>.

8.2.  Informative 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>.




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   [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>.

Authors' Addresses

   Liang Geng
   China Mobile
   Beijing 10053

   Email: gengliang@chinamobile.com


   Jingrong Xie
   Huawei Technologies

   Email: xiejingrong@huawei.com


   Mike McBride
   Futurewei

   Email: mmcbride7@gmail.com


   Gang Yan
   Huawei Technologies

   Email: yangang@huawei.com






















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