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Use of BIER IPv6 Encapsulation (BIERv6) for Multicast VPN in Non-MPLS IPv6 networks
draft-xie-bier-ipv6-mvpn-00

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This is an older version of an Internet-Draft whose latest revision state is "Expired".
Authors Jingrong Xie , Mike McBride , Senthil Dhanaraj , Liang Geng
Last updated 2019-03-11
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draft-xie-bier-ipv6-mvpn-00
Network Working Group                                             J. Xie
Internet-Draft                                                M. McBride
Intended status: Standards Track                             S. Dhanaraj
Expires: September 12, 2019                          Huawei Technologies
                                                                 L. Geng
                                                            China Mobile
                                                          March 11, 2019

 Use of BIER IPv6 Encapsulation (BIERv6) for Multicast VPN in Non-MPLS
                             IPv6 networks
                      draft-xie-bier-ipv6-mvpn-00

Abstract

   This draft defines the procedures and messages for using Bit Index
   Explicit Replication (BIER) for Multicast VPN Services in Non-MPLS
   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 Non-MPLS 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 September 12, 2019.

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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 . . . . . . . . . . . . . . . . . . . .   5
   5.  GTM over BIERv6 Core  . . . . . . . . . . . . . . . . . . . .   7
   6.  Data Plane  . . . . . . . . . . . . . . . . . . . . . . . . .   8
     6.1.  Encapsulation of Multicast Traffic  . . . . . . . . . . .   8
     6.2.  MTU . . . . . . . . . . . . . . . . . . . . . . . . . . .   8
     6.3.  TTL . . . . . . . . . . . . . . . . . . . . . . . . . . .   8
   7.  Security Considerations . . . . . . . . . . . . . . . . . . .   9
   8.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   9
   9.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   9
   10. References  . . . . . . . . . . . . . . . . . . . . . . . . .   9
     10.1.  Normative References . . . . . . . . . . . . . . . . . .   9
     10.2.  Informative References . . . . . . . . . . . . . . . . .  10
   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 Non-MPLS IPv6 networks using the BIER IPv6 encapsulation
   format defined in [I-D.xie-bier-ipv6-encapsulation].

   SRv6 explained in [I-D.ietf-spring-segment-routing] refers to the
   deployment of segment routing in Non-MPLS IPv6 networks.
   [I-D.filsfils-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

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   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
   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-idr-srv6-vpn] 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 BIERv6 Networks.  It defines a method to use an
   SRv6 Service SID like End.DTx as source address to identify the MVPN
   instance at the Egress PE.  While the End.DTx is used as IPv6
   destination address in unicast L3VPN scenarios as defined in
   [I-D.dawra-idr-srv6-vpn], this document extends the use of End.DTx as
   IPv6 source address.  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 [I-D.ietf-bier-mvpn].

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

   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-idr-srv6-vpn] is also required, and the [RFC5549] may be
   required further.

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

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

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

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

   o  SRv6 L3 Service - L3VPN/Global-L3 service in Non-MPLS SRv6 network
      defined in [I-D.dawra-idr-srv6-vpn], or MVPN/GTM service in Non-
      MPLS BIERv6 network 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 [I-D.ietf-bier-mvpn].  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 End.DTx IPv6 address of the
   BFIR is used to identify the VRF instead of a MPLS Label.  The
   End.DTx IPv6 Address (End.DT6 or End.DT4 or End.DT46) MUST be carried
   within an SRv6 L3 Service TLV [I-D.dawra-idr-srv6-vpn] 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 End.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 End.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 Non-MPLS BIER header, it retrieves the
   End.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.

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4.  MVPN over BIERv6 Core

   [I-D.ietf-bier-mvpn] 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 in addition to support BIER as a P-tunnel in Non-MPLS
   IPv6 networks.

   In a Non-MPLS 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 [I-D.ietf-bier-mvpn]
   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 End.DTx IPv6 address uniquely identifying
      the MVPN instance.

   If the VPN is IPv4 VPN, the End.DTx can be either End.DT4 or
   End.DT46.  If the VPN is IPv6 VPN, the End.DTx can be either End.DT6
   or End.DT46.  By default, the distribution of the x-PMSI A-D routes
   uses the same End.DTx as the ones used for the distribution of VPN-IP
   unicast routes.  That is, by default, the x-PMSI A-D route MUST carry
   the same SRv6-Service-SID used by the unicast routing for L3VPN.  The

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   default could be modified via configuration by having a End.DTx used
   for the BGP-MVPN x-PMSI A-D routes being distinct from the ones used
   for the VPN-IP unicast routes.

   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 [I-D.ietf-bier-mvpn] 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 End.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 End.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 End.DTx
   located in.

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

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

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 End.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.

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6.  Data Plane

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=End.DTx  |    | ( SA=End.DTx  |
                 |   DA=mcBIER ) |    |   DA=mcBIER ) |
                 +---------------+    +---------------+
                 | 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.

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].

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7.  Security Considerations

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

8.  IANA Considerations

   No IANA allocation is required.

9.  Acknowledgements

   TBD.

10.  References

10.1.  Normative References

   [I-D.dawra-idr-srv6-vpn]
              Dawra, G., Filsfils, C., Dukes, D., Brissette, P.,
              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, "BGP
              Signaling for SRv6 based Services.", draft-dawra-idr-
              srv6-vpn-05 (work in progress), October 2018.

   [I-D.filsfils-spring-srv6-network-programming]
              Filsfils, C., Camarillo, P., Leddy, J.,
              daniel.voyer@bell.ca, d., Matsushima, S., and Z. Li, "SRv6
              Network Programming", draft-filsfils-spring-srv6-network-
              programming-07 (work in progress), February 2019.

   [I-D.ietf-bier-mvpn]
              Rosen, E., Sivakumar, M., Aldrin, S., Dolganow, A., and T.
              Przygienda, "Multicast VPN Using BIER", draft-ietf-bier-
              mvpn-11 (work in progress), March 2018.

   [I-D.ietf-spring-segment-routing]
              Filsfils, C., Previdi, S., Ginsberg, L., Decraene, B.,
              Litkowski, S., and R. Shakir, "Segment Routing
              Architecture", draft-ietf-spring-segment-routing-15 (work
              in progress), January 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-00 (work in
              progress), March 2019.

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   [RFC5549]  Le Faucheur, F. and E. Rosen, "Advertising IPv4 Network
              Layer Reachability Information with an IPv6 Next Hop",
              RFC 5549, DOI 10.17487/RFC5549, May 2009,
              <https://www.rfc-editor.org/info/rfc5549>.

   [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>.

   [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>.

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>.

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Authors' Addresses

   Jingrong Xie
   Huawei Technologies

   Email: xiejingrong@huawei.com

   Mike McBride
   Huawei Technologies

   Email: michael.mcbride@huawei.com

   Senthil Dhanaraj
   Huawei Technologies

   Email: senthil.dhanaraj@huawei.com

   Liang Geng
   China Mobile

   Email: gengliang@chinamobile.com

Xie, et al.            Expires September 12, 2019              [Page 11]