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Versions: 00 01

Network Working Group                                             J. Xie
Internet-Draft                                       Huawei Technologies
Intended status: Standards Track                              M. McBride
Expires: January 2, 2020                                       Futurewei
                                                             S. Dhanaraj
                                                     Huawei Technologies
                                                                 L. Geng
                                                            China Mobile
                                                            July 1, 2019


   Use of BIER IPv6 Encapsulation (BIERv6) for Multicast VPN in IPv6
                                networks
                      draft-xie-bier-ipv6-mvpn-01

Abstract

   This draft defines the procedures and messages for using Bit Index
   Explicit Replication (BIER) for Multicast VPN Services in IPv6
   networks using the BIER IPv6 encapsulation.  It provides a migration
   path for Multicast VPN service using BIER MPLS encapsulation in MPLS
   networks to multicast VPN service using BIER IPv6 encapsulation
   (BIERv6) in IPv6 networks.

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 2, 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
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   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.  Use of PTA and Prefix-SID Attribute in x-PMSI A-D Routes  . .   4
   4.  MVPN over BIERv6 Core . . . . . . . . . . . . . . . . . . . .   4
   5.  GTM over BIERv6 Core  . . . . . . . . . . . . . . . . . . . .   7
   6.  Data Plane  . . . . . . . . . . . . . . . . . . . . . . . . .   7
     6.1.  Encapsulation of Multicast Traffic  . . . . . . . . . . .   8
     6.2.  MTU . . . . . . . . . . . . . . . . . . . . . . . . . . .   9
     6.3.  TTL . . . . . . . . . . . . . . . . . . . . . . . . . . .   9
   7.  Security Considerations . . . . . . . . . . . . . . . . . . .   9
   8.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   9
   9.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .  10
   10. References  . . . . . . . . . . . . . . . . . . . . . . . . .  10
     10.1.  Normative References . . . . . . . . . . . . . . . . . .  10
     10.2.  Informative References . . . . . . . . . . . . . . . . .  11
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  11

1.  Introduction

   Bit Index Explicit Replication (BIER) [RFC8279] is an architecture
   that provides optimal multicast forwarding without requiring
   intermediate routers to maintain any per-flow state by using a
   multicast-specific BIER header.  BIERv6 refers to the deployment of
   BIER in IPv6 networks using the BIER IPv6 encapsulation format
   defined in [I-D.xie-bier-ipv6-encapsulation].

   [I-D.ietf-spring-srv6-network-programming] introduces the Network
   programming concepts in SRv6 networks and explains how the 128-bit
   IPv6 address can be used as SRv6 SID in the format LOC:FUNCT, where
   LOC part of the SID is routable, while FUNCT part of the SID is an
   opaque identification of a local function bound to the SID.  It has



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   also defined some well known standard functions like End.DT4 -
   Endpoint with decaps and IPv4 table lookup for L3VPN (equivalent to
   per-VRF VPN label).

   [I-D.dawra-bess-srv6-services] defines the TLVs to associate a
   function like End.DT4 with the L3VPN Unicast routes advertised via
   BGP.  It also details how the functions of End.DT4, End.DT6, End.DT46
   (End.DTx) can be used to identify a L3VPN/EVPN instead of using a VPN
   Label in MPLS-VPN [RFC4364] of the received data packet and thereby
   realize the L3VPN Services in the SRv6 Networks.  However, it covers
   unicast services exclusively.

   This document describes a method to realize MVPN services using BIER
   as a P-tunnel in the IPv6 Networks (BIERv6 Networks).  It defines a
   method to use an SRv6 Service SID, called Src.DTx in this document,
   as source address of an IPv6 header, to identify the MVPN instance at
   the Egress PE.  The LOC part and FUNCT part of this SRv6 Service SID
   represent the context and the upstream-assigned VPN Label
   respectively in MVPN scenario's as defined in [RFC8556].

   In particular, MVPN deployment in IPv6 networks relies on L3VPN
   deployment on IPv6 networks firstly, thus the c-multicast routing
   procedure like UMH Selection can be done.  The L3VPN deployment in
   IPv6 networks can be referred to [I-D.dawra-bess-srv6-services].

   GTM defined in [RFC7716] is also covered in this document, as GTM
   shares the same BGP-MVPN signaling, while providing an approach of
   Non-VPN multicast over a service provider core with various P-tunnel
   type.  For the same reason of UMH selection, and the requirement of
   basic operation like ping (e.g, to the multicast source address), the
   Global IPv4/IPv6 over SRv6 Core as described in
   [I-D.dawra-bess-srv6-services] is also required.

2.  Terminology

   Readers of this document are assumed to be familiar with the
   terminology and concepts of the documents listed as Normative
   References.  Additionally the following terms are used through out
   the document.

   o  BIERv6 - BIER in IPv6 networks using the BIERv6 encapsulation
      format defined in [I-D.xie-bier-ipv6-encapsulation].

   o  SRv6 - Segment Routing instantiated on the IPv6 dataplane as
      defined in [I-D.ietf-spring-srv6-network-programming].

   o  SRv6 SID - SRv6 Segment Identifier as defined in
      [I-D.ietf-spring-srv6-network-programming].



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   o  End.DTx - Refers to the functions End.DT6, End.DT4, End.DT46
      defined in [I-D.ietf-spring-srv6-network-programming].

   o  Src.DTx - Refers to the functions Src.DT4, Src.DT6, Src.DT46
      defind in this document.

   o  SRv6 L3 Service - L3VPN/Global-L3 service in SRv6 networks defined
      in [I-D.dawra-bess-srv6-services], or MVPN/GTM service in BIERv6
      networks defined in this document.

3.  Use of PTA and Prefix-SID Attribute in x-PMSI A-D Routes

   The BGP-MVPN I-PMSI A-D (Type 1) or S-PMSI A-D (Type 3) route (called
   x-PMSI A-D route in this document), advertised by Ingress PE carries
   the BIER (Type 11) PTA as specified in [RFC8556].  The BIER PTA
   carried in the x-PMSI A-D route is used for explicitly tracking the
   receiver-site PEs which are interested in a specific multicast flow.
   It includes three BIER-specific fields, Sub-domain-id, BFR-id, and
   BFR-prefix.  For BIER P-tunnel using the BIERv6 encapsulation in IPv6
   networks, the BFR-prefix field in the PTA MUST be set to the BFIR
   IPv6 prefix and the MPLS Label field in the PTA MUST set to 0.  For
   MVPN over BIERv6, the Src.DTx IPv6 address of the BFIR is used to
   identify the VRF instead of an MPLS Label.  The Src.DTx IPv6 Address
   (Src.DT6 or Src.DT4 or Src.DT46) MUST be carried within an SRv6 L3
   Service TLV [I-D.dawra-bess-srv6-services] of BGP Prefix-SID
   attribute in the x-PMSI A-D route.

   The Ingress PE encapsulates the c-multicast IP packet with BIERv6
   header and the source address in the outer IPv6 header will be set to
   the Src.DTx IPv6 address advertised in the BGP-MVPN x-PMSI A-D
   routes.  See section 3 of [I-D.xie-bier-ipv6-encapsulation] for the
   detailed packet format.

   Egress PE (BFER) receiving the x-PMSI A-D routes with BIER PTA and
   SRv6 L3 Service TLV learns the Src.DTx IPv6 address and uses it to
   identify the VRF of the c-multicast packet.

   When Egress PE receives a BIERv6 packet and the self bfr-id is set in
   the bit-string field of the BIERv6 header, it retrieves the Src.DTx
   IPv6 address from the source address of the IPv6 header to determine
   the VRF and the Address Family (AF) of the c-multicast data packet,
   and performs the MFIB lookup in the corresponding table.

4.  MVPN over BIERv6 Core

   [RFC8556] specifies the protocol and procedures to be followed by the
   Ingress and Egress PEs to use BIER as a P-tunnel for MVPN in MPLS
   networks.  This section specifies the required changes and procedures



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   in addition to support BIER as a P-tunnel in IPv6 networks using
   BIERv6.

   In a IPv6 service provider network, many of the IP address fields
   used in the BGP-MVPN routes are IPv6 address as specified in
   [RFC6515].  These are listed below.

   o  "Originating Router's IP Address" in the NLRI of Type 1 or Type 3
      BGP-MVPN route is an IPv6 address.

   o  "Network Address of Next Hop" field in the MP_REACH_NLRI attribute
      is an IPv6 address.

   o  Route Targets Extended Community (EC) used in C-multicast join
      (Type 6 or 7) route or Leaf A-D (Type 5) route is an IPv6 Address
      Specific Extended Community, where the Global Administrator field
      will be an IPv6 address identifies the Upstream PE or the UMH.

   o  "VRF Route Import Extended Community (EC)" carried by unicast VPN-
      IPv4 or VPN-IPv6 routes as [RFC6515] specifies, or SAFI 1, 2, or 4
      unicast routes, or MVPN (SAFI 5) Source-Active routes as [RFC7716]
      specifies.

   On the Ingress PE (BFIR), the BGP-MVPN x-PMSI A-D route is
   constructed as per the procedures specified in [RFC8556] and with the
   following specifications.

   o  MPLS Label field in the BIER PTA MUST be set to Zero.

   o  BFR-prefix field in the BIER PTA MUST be set to the Ingress PEs
      (BFIR) IPv6 BFR-Prefix Address.  It does not need to be the same
      as the other IPv6 address of the x-PMSI AD route.

   o  Route MUST also carry an BGP Prefix SID attribute with an SRv6 L3
      Service TLV carrying an Src.DTx IPv6 address uniquely identifying
      the MVPN instance.

   If the MVPN is IPv4 MVPN, the Src.DTx can be either Src.DT4 or
   Src.DT46.  If the MVPN is IPv6 MVPN, the Src.DTx can be either
   Src.DT6 or Src.DT46.  The distribution of the x-PMSI A-D routes uses
   the Src.DTx according to the local configuration, and is independent
   to the use of End.DTx in VPN-IP unicast routes of this VPN.  For
   example, one can use End.DT46 for VPNv4 and VPNv6 unicast routes, but
   use Src.DT4 for the MVPN routes for the same VPN.  Another example,
   one can use End.DX for VPNv4 unicast routes, but use Src.DT46 for the
   MVPN routes for the same VPN.





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   BFIR MAY carry the BGP Prefix-SID attribute only in I-PMSI A-D route
   when I-PMSI A-D route is used, while other S-PMSI A-D routes do not
   carry the BGP Prefix-SID attribute.

   BFIR MAY carry the BGP Prefix-SID attribute only in wildcard S-PMSI
   A-D routes when the "S-PMSI Only" mode as described in [RFC6625] is
   used, while other S-PMSI A-D routes do not carry the BGP Prefix-SID
   attribute.

   On the Egress PE (BFER), the BGP-MVPN x-PMSI A-D route is processed
   as per the procedures specified in [RFC8556] and with the following
   specifications:

   o  The MPLS Label field in the BIER PTA of the BGP-MVPN x-PMSI A-D
      route MUST be ignored and MUST not be used for the identification
      of the VRF.

   o  The BGP-MVPN x-PMSI A-D route MUST be dropped if the BFR-prefix
      field in the BIER PTA is not an IPv6 address.

   o  The BGP-MVPN x-PMSI A-D route MUST be dropped if it does not carry
      a Src.DTx IPv6 address in the SRv6 L3 Service TLV in BGP Prefix
      SID attribute.

   o  Leaf A-D route originated by the Egress PE (BFER) MUST carry the
      BIER PTA with the BFR-prefix field set to the BFER IPv6 BFR-
      prefix.

   Valid BGP-MVPN x-PMSI A-D route received by an Egress PE (BFER) is
   stored locally, and the Src.DTx IPv6 Address carried in the SRv6 L3
   service TLV is used to identify the VRF of a c-multicast data packet.
   This may be populated into forwarding table only when there is
   c-multicast flow state with UMH of the specific BFIR this Src.DTx
   located in.

   If more than one x-PMSI A-D routes belonging to the same VRF has
   different Src.DTx value, the processing is determined by the local
   policy of the BFER.

   If more than one x-PMSI A-D routes belonging to different VRF has the
   same Src.DTx value, the BFER must log an error, and a BIERv6 packet
   with this Src.DTx as the IPv6 source address MUST be dropped.

   The BGP Prefix-SID attribute (which may include the Src.DTx in SRv6
   L3 Service TLV) MUST NOT be carried in Leaf A-D route upon sending,
   and MUST be ignored upon reception.





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5.  GTM over BIERv6 Core

   As specified in [RFC7716], Global Table Multicast (GTM) uses the same
   Subsequent Address Family Identifier (SAFI) value, the same Network
   Layer Reachability Information (NLRI) format, and the same procedures
   of MVPN with only a few adaptions.  It support for both IPv4 and IPv6
   multicast flows over either an IPv4 or IPv6 SP infrastructure.  GTM
   over BIERv6 core is obviously a case of IPv4/IPv6 multicast over an
   IPv6 SP infrastructure with BIERv6 data-plane.

   The BIER (Type 11) PTA attribute and the BGP Prefix-SID attribute are
   carried in the x-PMSI A-D route in GTM cases.  When the a BGP-MVPN
   x-PMSI A-D route is received by Egress PE, it is stored locally, and
   the Src.DTx IPv6 Address of the Ingress PE in the route is used to
   determine the VRF of a packet, which is the 'public' VRF in the case
   of GTM.

   There are some other attributes listed below for GTM over a BIERv6
   core:

   o  Route Distinguishers - the RD field of a BGP-MVPN route's NLRI
      MUST be set to zero (i.e., to 64 bits of zero) to represent a Non-
      VPN GTM.  See section 2.2 of [RFC7716].

   o  Route Targets Extended Community (EC) - The RT EC carried by the
      BGP-MVPN C-multicast (Type 6 or 7) route or Leaf A-D (Type 4)
      route MUST be an IPv6-address-specific Extended Community (EC).
      The Global Administrator field identifies the Upstream PE or the
      UMH, and the Local Administrator field MUST always be set to zero
      in GTM case.

   o  VRF Route Import Extended Community (EC) - The VRF Route Import EC
      used in BIERv6 core MUST be an IPv6-address-specific EC if used,
      either used in UMH-eligible unicast routes having a SAFI of 1, 2,
      or 4, or used in the MVPN (SAFI of 5) Source Active A-D route.

   GTM IPv4 multicast over an BIERv6 core may be considered an
   alternative to support IPv4 IPTV content delivery during transition
   to IPv6 period comparing to [RFC8114].  They both use IPv4-in-IPv6
   encapsulation, while BIERv6 uses an additional BIER header within an
   IPv6 Extension header to support stateless core.

6.  Data Plane








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6.1.  Encapsulation of Multicast Traffic

   BIER IPv6 encapsulation (BIERv6) [I-D.xie-bier-ipv6-encapsulation] is
   used for forwarding the c-multicast traffic through an IPv6 core.
   The following diagram shows the progression of an MVPN c-multicast
   packet as it enters and leaves the intra-AS service-provider network.

                 +---------------+    +---------------+
                 | P-IPv6 Header |    | P-IPv6 Header |
                 | (SA=Src.DTx   |    | (SA=Src.DTx   |
                 |  DA=End.BIER) |    |  DA=End.BIER) |
                 +---------------+    +---------------+
                 | P-IPv6 ExtHdr |    | P-IPv6 ExtHdr |
                 | (BIER header) |    | (BIER header) |
++=========++    ++=============++    ++=============++    ++=========++
||C-IP Hdr ||    ||  C-IP Hdr   ||    ||  C-IP Hdr   ||    ||C-IP Hdr ||
++=========++ >> ++=============++ >> ++=============++ >> ++=========++
||C-Payload||    ||  C-Payload  ||    ||  C-Payload  ||    ||C-Payload||
++=========++    ++=============++    ++=============++    ++=========++
CE1-----------PE1------------------P2------------------PE2-----------CE2

                    Figure 1: BIERv6 MVPN/GTM Intra-AS

   In case of inter-AS scenario, BIERv6 packets may travel through
   unicast to a Boarder Router (BR), and then replicate in a single
   intra-AS BIERv6 domain.  How such non-segmented BIERv6 scenario can
   be supported is outside the scope of this document.

   How segmented MVPN, for example, between BIERv6 and BIERv6, or
   between BIERv6 and Ingress Replication(IR) in Non-MPLS IPv6 networks,
   is outside the scope of this document.

   The Src.DTx SHOULD support as destination address of an ICMPv6
   packet.  The following is an example pseudo-code of the Src.DTx
   function as destination address:

       1. IF Last_NH = ICMPv6   ;;Ref1
       2.   Send to CPU.
       3. ELSE
       4.   Drop the packet.

   Ref1: ICMPv6 packet using Src.DT4, Src.DT6 or Src.DT46 as destination
   address.








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6.2.  MTU

   Each BFIR is expected to know the Maximum Transmission Unit (MTU) of
   the BIER domain.  This may be known by provisioning, or by method
   specified in [draft-ietf-bier-mtud].  The section 3 of [RFC8296]
   applies.

6.3.  TTL

   The ingress PE (BFIR) should not copy the Time to Live (TTL) field
   from the payload IP header received from a CE router to the delivery
   IP header.  Setting the TTL of the delivery IP header is determined
   by the local policy of the ingress PE (BFIR) router per section 3 of
   [RFC8296].

7.  Security Considerations

   The security considerations SEC-1, SEC-2, SEC-3 defined in
   [I-D.ietf-spring-srv6-network-programming] apply equally to this
   document.

8.  IANA Considerations

   Allocation is expected from IANA for the following Src.DTx functions
   codepoints from the "SRv6 Endpoint Behaviors" sub-registry.

   Values 68, 69, 70 is suggested for Src.DT6, Src.DT4, Src.DT46
   respectively.

   +-------+--------+--------------------------+------------+
   | Value |  Hex   |    Endpoint function     | Reference  |
   +-------+--------+--------------------------+------------+
   | TBD   |  TBD   |    Src.DT6               | This draft |
   +-------+--------+--------------------------+------------+
   | TBD   |  TBD   |    Src.DT4               | This draft |
   +-------+--------+--------------------------+------------+
   | TBD   |  TBD   |    Src.DT46              | This draft |
   +-------+--------+--------------------------+------------+

  Src.DT6   Source address indicating decapsulation and IPv6 table lookup
            e.g. IPv6-MVPN (equivalent to per-VRF VPN label in RFC8556)
  Src.DT4   Source address indicating decapsulation and IPv4 table lookup
            e.g. IPv4-MVPN (equivalent to per-VRF VPN label in RFC8556)
  Src.DT46  Source address indicating decapsulation and IP table lookup
            e.g. IP-MVPN (equivalent to per-VRF VPN label)






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9.  Acknowledgements

   TBD.

10.  References

10.1.  Normative References

   [I-D.dawra-bess-srv6-services]
              Dawra, G., Filsfils, C., Dukes, D., Brissette, P.,
              Sethuram, S., Camarillo, P., Leddy, J.,
              daniel.voyer@bell.ca, d., daniel.bernier@bell.ca, d.,
              Steinberg, D., Raszuk, R., Decraene, B., Matsushima, S.,
              and S. Zhuang, "SRv6 BGP based Overlay services", draft-
              dawra-bess-srv6-services-00 (work in progress), March
              2019.

   [I-D.ietf-spring-srv6-network-programming]
              Filsfils, C., Camarillo, P., Leddy, J.,
              daniel.voyer@bell.ca, d., Matsushima, S., and Z. Li, "SRv6
              Network Programming", draft-ietf-spring-srv6-network-
              programming-00 (work in progress), April 2019.

   [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.

   [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>.

   [RFC6625]  Rosen, E., Ed., Rekhter, Y., Ed., Hendrickx, W., and R.
              Qiu, "Wildcards in Multicast VPN Auto-Discovery Routes",
              RFC 6625, DOI 10.17487/RFC6625, May 2012,
              <https://www.rfc-editor.org/info/rfc6625>.

   [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>.







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   [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>.

   [RFC8296]  Wijnands, IJ., Ed., Rosen, E., Ed., Dolganow, A.,
              Tantsura, J., Aldrin, S., and I. Meilik, "Encapsulation
              for Bit Index Explicit Replication (BIER) in MPLS and Non-
              MPLS Networks", RFC 8296, DOI 10.17487/RFC8296, January
              2018, <https://www.rfc-editor.org/info/rfc8296>.

   [RFC8556]  Rosen, E., Ed., Sivakumar, M., Przygienda, T., Aldrin, S.,
              and A. Dolganow, "Multicast VPN Using Bit Index Explicit
              Replication (BIER)", RFC 8556, DOI 10.17487/RFC8556, April
              2019, <https://www.rfc-editor.org/info/rfc8556>.

10.2.  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>.

   [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

   Jingrong Xie
   Huawei Technologies

   Email: xiejingrong@huawei.com


   Mike McBride
   Futurewei

   Email: mmcbride7@gmail.com


   Senthil Dhanaraj
   Huawei Technologies

   Email: senthil.dhanaraj@huawei.com





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Internet-Draft                 BIERv6 MVPN                     July 2019


   Liang Geng
   China Mobile

   Email: gengliang@chinamobile.com















































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