[Docs] [txt|pdf] [Tracker] [Email] [Nits]

Versions: 00 01

PIM Working Group                                            Yisong Liu
Internet Draft                                      Huawei Technologies
Intended status: Standards Track                          June 26, 2019
Expires: December 26, 2019



    Multicast-Only Fast Reroute Based on Topology Independent Loop-free
                          Alternate Fast Reroute
                       draft-liu-pim-mofrr-tilfa-00


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), its areas, and its working groups.  Note that
   other groups may also distribute working documents as Internet-
   Drafts.

   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."

   The list of current Internet-Drafts can be accessed at
   http://www.ietf.org/ietf/1id-abstracts.txt

   The list of Internet-Draft Shadow Directories can be accessed at
   http://www.ietf.org/shadow.html

   This Internet-Draft will expire on December 26, 2019.

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
   (http://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.




Liu, et al.            Expires December, 2019                 [Page 1]


Internet-Draft           MoFRR based on TI-LFA                June 2019


Abstract

   Multicast-only Fast Reroute (MoFRR) has been defined in [RFC7431],
   but the selection of the secondary multicast next hop only according
   to the loop-free alternate fast reroute, which has restrictions in
   multicast deployments. This document describes a mechanism for
   Multicast-only Fast Reroute by using Topology Independent Loop-free
   Alternate fast reroute, which is independent of network topology and
   can achieve covering more network environments.

Table of Contents


   1. Introduction ................................................ 2
      1.1. Requirements Language .................................. 3
      1.2. Terminology ............................................ 3
   2. Problem Statement ........................................... 3
   3. Solution .................................................... 4
      3.1. Secondary UMH Selection in PIM ......................... 5
      3.2. Secondary UMH Selection in MLDP ........................ 5
      3.3. Extension Protocol Fields Conflict ..................... 6
   4. Packet Format ............................................... 6
      4.1. PIM Join Message Extension ............................. 7
      4.2. MLDP Label Mapping Message Extension ................... 8
   5. IANA Considerations ........................................ 11
   6. Security Considerations .................................... 11
   7. References ................................................. 11
      7.1. Normative References .................................. 11
      7.2. Informative References ................................ 12
   8. Acknowledgments ............................................ 12

1. Introduction

   As the deployment of video services, operators are paying more and
   more attention to solutions that minimize the service disruption due
   to faults in the IP network carrying the packets for these services.
   Multicast-only Fast Reroute (MoFRR) has been defined in [RFC7431],
   which can minimize multicast packet loss in a network when node or
   link failures occur by making simple enhancements to multicast
   routing protocols such as Protocol Independent Multicast (PIM) and
   Multipoint LDP (mLDP). But the selection of the secondary multicast
   next hop only according to the loop-free alternate fast reroute in
   [RFC7431], and there are limitations in multicast deployments for
   this mechanism. This document describes a new mechanism for
   Multicast-only Fast Reroute using Topology Independent Loop-free
   Alternate (TILFA) fast reroute, which is independent of network
   topology and can achieve covering more network environments.



Liu, et al.            Expires December, 2019                 [Page 2]


Internet-Draft           MoFRR based on TI-LFA                June 2019


    1.1. 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.

    1.2. Terminology

   This document use the terms defined in [RFC7431], and also use the
   concepts defined in [RFC7490]. The specific content of each term is
   not described in this document.

2. Problem Statement

   In [RFC7431] section 3, the secondary Upstream Multicast Hop (UMH)
   of PIM and mLDP for MoFRR is a loop-free alternate (LFA). However,
   the traditional LFA mechanism needs to satisfy at least one neighbor
   whose next hop to the destination node is an acyclic next hop,
   existing limitations in network deployments, and can only cover part
   of the network topology environments. In some network topology, the
   corresponding secondary UMH cannot be calculated, so PIM and MLDP
   cannot establish a standby multicast tree and cannot implement MoFRR
   protection. Therefore, the current MoFRR of PIM and MLDP is only
   available in the network topology applicable to LFA.

   The remote loop-free alternate (RLFA) defined in [RFC7490] is
   extended from the LFA and can cover more network deployment
   scenarios through the tunnel as an alternate path. The RLFA
   mechanism needs to satisfy at least one node assumed to be N in the
   network that the fault node is neither on the path from the source
   node to the N node, nor on the path from the N node to the
   destination node. RLFA only has enhancement compared to LFA but
   still has limitations in network deployments.

   [I-D.ietf-rtgwg-segment-routing-ti-lfa] defined a unicast FRR
   solution based on the TILFA mechanism. The TILFA mechanism can
   express the backup path with an explicit path, and has no constraint
   on the topology, providing a more reliable FRR mechanism. The
   unicast traffic can be forwarded according to the explicit path list
   as an alternate path to implement unicast traffic protection, and
   can achieve full coverage of various networking environments.

   The alternate path provided by the TILFA mechanism is actually a
   Segment List, including one or more Adjacency SIDs of one or more
   links between the P space and the Q space, and the NodeSID of P
   space node. PIM and MLDP can look up the corresponding node IP
   address in the unicast route according to the NodeSID, and the IP


Liu, et al.            Expires December, 2019                 [Page 3]


Internet-Draft           MoFRR based on TI-LFA                June 2019


   addresses of the two endpoints of the corresponding link in the
   unicast route according to the Adjacency SIDs, but the multicast
   protocol packets cannot be directly sent along the path of the
   Segment List.

   Both the PIM join message and the MLDP Label Mapping message need to
   be sent hop-by-hop to establish a standby multicast tree. However,
   not all of the nodes and links on the unicast alternate path are
   included in the Segment List. If the PIM and MLDP protocol packets
   are transmitted only in unicast mode, then equivalently the PIM and
   MLDP packets are transmitted through the unicast tunnel like unicast
   traffic, and cannot pass through the intermediate nodes of the
   tunnel. The intermediate nodes of the alternate path cannot forward
   multicast traffic because there are no PIM or MLDP state entries on
   the nodes. PIM needs to create entries on the device hop-by-hop and
   generate an incoming interface and an outgoing interface list. MLDP
   needs to create entries on the device hop-by-hop and generate an
   incoming label and an outgoing label list. So it can form an end-to-
   end complete multicast tree for forwarding multicast traffic.
   Therefore, it is not possible to send PIM and MLDP packets like
   unicast traffic according to the Segment List path and establish a
   standby multicast tree.

   It is available in principle that the path information of the
   Segment List is added to the PIM and MLDP packets to guide the hop-
   by-hop RPF selection. The IP address of the node corresponding to
   the NodeSID can be used as the segmented root node, and the IP
   addresses of the interfaces at both endpoints of the link
   corresponding to the Adjacency SID can be used directly as the local
   upstream interface and upstream neighbor, but there is currently no
   field in protocol packet to carry the explicit path specified by the
   Segment List. For the PIM protocol, the PIM RPF Vector attribute was
   defined in [RFC5496], which can carry the node IP address
   corresponding to the NodeSID. The Explicit RPF Vector was defined in
   [RFC7891], which can carry the peer IP address corresponding to the
   Adjacency SID, but if there are multiple same peer IP addresses
   corresponding to the Adjacency SID (i.e. anycast IP address), the
   upstream neighbor of RPF selection may be different from the actual
   upstream link corresponding to the Adjacency SID, which can make the
   PIM join path and the TILFA calculation path inconsistent. For the
   MLDP protocol, there is also no field defined in the MLDP protocol
   Label Mapping message that can carry the explicit path of the
   Segment List.

3. Solution

   An Upstream Multicast Hop (UMH) is a candidate next-hop that can be
   used to reach the root of the tree.  In This document the secondary
   UMH is based on unicast routing to find Segment List calculated by


Liu, et al.            Expires December, 2019                 [Page 4]


Internet-Draft           MoFRR based on TI-LFA                June 2019


   TILFA. With MoFRR, The procedures for determining the secondary UMH
   and establishing standby multicast tree are different for PIM and
   mLDP.

   This document extends the PIM and mLDP protocol, to establish the
   standby multicast tree according to the Segment List calculated by
   TILFA, and can achieve full coverage of various networking
   environments for MoFRR protection of multicast services.

   Assume that the Segment List calculated by TILFA is (NodeSID(A),
   AdjSID(A-B)). Node A belongs to the P Space, and node B belongs to
   the Q space. The IP address corresponding to NodeSID(A) can be
   looked up in the local link state database of the IGP protocol, and
   can be assumed to be IP-a. The IP addresses of the two endpoints of
   the link corresponding to AdjSID(A-B) can also be looked up in the
   local link state database of the IGP protocol, and can be assumed to
   be IP-La and IP-Lb.

    3.1. Secondary UMH Selection in PIM

   In the procedure of PIM, IP-a can be looked as the normal RPF vector
   attribute and added to the PIM join packet. IP-La and IP-Lb can be
   looked as the RPF Vector attribute of the adjacency relationship,
   called Adjacency RPF Vector, which is a new type of PIM join
   attributes, and added to the PIM join packet too.

   The PIM protocol firstly can select the RPF incoming interface and
   upstream towards IP-a, and can join hop-by-hop to establish the PIM
   standby multicast tree until the node A. On the node A, IP-Lb can be
   looked as one PIM neighbor. If there are multiple PIM neighbors with
   the same address IP-Lb, all of the corresponding local interfaces on
   the node A need to be checked. The interface that is the only one
   with the IP address IP-La can be looked as the RPF incoming
   interface. The node A can send the PIM join packet to the node B on
   the interface of IP-La, and IP-Lb is used as the RPF upstream
   address of the PIM join.

   After the PIM join packet is received on the node B, the PIM
   protocol can find no more join attributes and select the RPF
   incoming interface and upstream towards the multicast source
   directly, and then can continue to join hop-by-hop to establish the
   PIM standby multicast tree until the router directly connected the
   source.

    3.2. Secondary UMH Selection in MLDP

   In the procedure of MLDP, Explicit path TLV is newly defined in MLDP
   Label Mapping message to carry IP-a, IP-La and IP-Lb, which is
   contained in the field of Optional Parameters. IP-a can be looked as


Liu, et al.            Expires December, 2019                 [Page 5]


Internet-Draft           MoFRR based on TI-LFA                June 2019


   the segmented root node address and is added as the Node Address Sub
   TLV in the Explicit path TLV. IP-La and IP-Lb are added as the
   Adjacency Address Sub TLV in the Explicit Path TLV.

   The MLDP protocol can look up the upstream interface and the
   upstream LSR in the unicast route to IP-a, and can send the Label
   Mapping message hop-by-hop to establish the standby MPLS multicast
   tree to the node A. After the message is received on the node A, the
   Node Address Sub TLV corresponding to the IP-a can be deleted from
   the Label Mapping message.

   On the node A IP-Lb can be looked as one MLDP neighbor. If there are
   multiple MLDP neighbors with the same address IP-Lb, all of the
   corresponding local interfaces on the node A need to be checked. The
   interface that is the only one with the IP address IP-La can be
   looked as the upstream interface. The node A can send MLDP Label
   mapping message to the node B, and IP-Lb is used as the upstream LSR
   address.

   After the message is received on the node B, the Adjacency Address
   Sub TLV corresponding to the IP-La and IP-Lb is deleted from the
   Label Mapping message and if there is no more any sub TLV in the
   Explicit Path TLV then the TLV should be deleted. The MLDP protocol
   can select the upstream interface and the upstream LSR in the
   unicast route to the original root node directly, and can continue
   to send the Label Mapping message to establish the standby MPLS
   multicast tree to the original root node.

    3.3. Extension Protocol Fields Conflict

   PIM Adjacency RPF Vector attribute is newly defined in join
   attributes. If there are conflicts from multiple downstream PIM
   neighbors, the mechanism in [RFC5384] Section 3.3.3 can be used to
   select a PIM downstream neighbor with a numerically smallest IP
   address. If at least two neighbors have the same IP address, the
   interface index MUST be used as a tie breaker.

   In the Explicit Path TLV newly defined in MLDP Label Mapping
   message, if there are conflicts from multiple downstream MLDP
   neighbors, including the inconsistency of the Sub TLV types, and the
   inconsistency of the Sub TLV contents, and the inconsistency of the
   Sub TLV sequences, it is also recommended to use the mechanism in
   [RFC5384] Section 3.3.3.

4. Packet Format

   This section describes the format of PIM and mLDP protocol packet
   extension introduced by this document.



Liu, et al.            Expires December, 2019                 [Page 6]


Internet-Draft           MoFRR based on TI-LFA                June 2019


    4.1. PIM Join Message Extension


       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
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      | Addr Family   | Encoding Type | Rsrvd   |S|W|R|  Mask Len     |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |               Source Address
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+.....
      |F|E| Attr_Type | Length        | Value
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+.....
      |F|E| Attr_Type | Length        | Value
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+.....
           .                    .                     .
           .                    .                     .


   The original PIM join attribute already has been defined in
   [RFC5384]

   Attr_Type

   0- Vector ;

   4- Explicit RPF Vector ;

   Other existing definitions are not related to RPF Vector Attribute.

      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
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |F|E| Type      | Length        |        Value
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-.......


   The definition of Adjacency RPF Vector attribute

   F bit: 0, indicating that the unrecognized device does not forward
   the attribute

   E bit: indicates the last join attribute

   Type: TBD

   Length  depends on the address family of Encoded-Unicast address,
   including the length of 2 addresses.




Liu, et al.            Expires December, 2019                 [Page 7]


Internet-Draft           MoFRR based on TI-LFA                June 2019


   Value  Encoded-Unicast Address format defined in [RFC7761] Section
   4.9.1, including 2 addresses. The first one indicates the address of
   the local interface, and the second one indicates the address of the
   peer interface. Only the case of the same address family is
   supported.

    4.2. MLDP Label Mapping Message Extension


       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
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |0|   Label Mapping (0x0400)    |      Message Length           |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                     Message ID                                |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                     FEC TLV                                   |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                     Label TLV                                 |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                     Optional Parameters                       |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


   The LDP Label Mapping message format is defined in [RFC5036] Section
   3.5.7. The MLDP P2MP protocol uses the message to establish a P2MP
   multicast tree. The Optional Parameters field can be extended to
   carry the node or link IP address list specified by the Segment
   List.

       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
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |U|F|        Type               |            Length             |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                                                               |
      |                             Value                             |
      ~                                                               ~
      |                                                               |
      |                               +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                               |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


   The TLV format definition in [RFC5036] Section 3.3 can be used for
   the Explicit Path TLV carrying the specified path of the Segment
   List.



Liu, et al.            Expires December, 2019                 [Page 8]


Internet-Draft           MoFRR based on TI-LFA                June 2019


       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
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |1|0|        TBD1               |            Length             |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                                                               |
      |               Node Address Sub TLV                            |
      |               Adjacency Address Sub TLV                       |
      ~                                                               ~
      |                                                               |
      |                               +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                               |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


   The definition of Explicit Path TLV:

   U bit  Unknown TLV bit. 1 indicates the unknown TLV MUST be silently
   ignored and the rest of the message processed as if the unknown TLV
   did not exist.

   F bit  Forward unknown TLV bit. 0 indicates the unknown TLV is not
   forwarded with the containing message.

   Type TBD1

   Length contains all Sub-TLV lengths

   Value Contains one or more Sub-TLVs, which are recorded in the order
   of TILFA's Segment List. There are two types of Sub TLVs now. One of
   the two types is called Node Address Sub TLV which carries the node
   IP address corresponding to the NodeSID, and the other is called
   Adjacency Address Sub TLV which carries the local interface address
   and the peer interface address corresponding to the Adjacency SID.

       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
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |1|0|E|      Type = TBD2        |            Length             |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                                                               |
      |                      Node Address                             |
      ~                                                               ~
      |                                                               |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+




Liu, et al.            Expires December, 2019                 [Page 9]


Internet-Draft           MoFRR based on TI-LFA                June 2019


   Node Address Sub TLV carrying the node IP address corresponding to
   the NodeSID

   U bit  1 indicates the unknown TLV MUST be silently ignored and the
   rest of the message processed as if the unknown TLV did not exist.

   F bit  0 indicates the unknown TLV is not forwarded with the
   containing message.

   E bit 1 indicates the last Sub TLV.

   Type TBD2

   Length  IPv4 address 4 octet  IPv6 address 16 octet

   Value  The IP address of the node corresponding to the NodeSID in
   the Segment List generated by TILFA



       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
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |1|0|E|      Type = TBD3        |            Length             |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                                                               |
      |                 Local Interface Address                       |
      |                 Remote Interface Address                      |
      ~                                                               ~
      |                                                               |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


   Adjacency Address Sub TLV carrying the local interface address and
   the peer interface address corresponding to the Adjacency SID

   U bit  1 indicates the unknown TLV MUST be silently ignored and the
   rest of the message processed as if the unknown TLV did not exist.

   F bit  0 indicates the unknown TLV is not forwarded with the
   containing message.

   E bit 1 indicates the last Sub TLV.

   Type TBD3




Liu, et al.            Expires December, 2019                [Page 10]


Internet-Draft           MoFRR based on TI-LFA                June 2019


   Length  IPv4 address 8 octet  IPv6 address 32 octet

   Value  The IP address of the local interface and the IP address of
   the peer interface corresponding to the Adjacency SID in the Segment
   List generated by TILFA must be recorded in order, and MUST be the
   same address family.

5. IANA Considerations

   This document requests IANA to assign a registry for Adjacency RPF
   Vector in PIM Join Attribute and the Explicit Path TLV  Node Address
   Sub TLV, Adjacency Address Sub TLV in the Optional Parameters field
   of MLDP P2MP Label Mapping message. The assignment is requested
   permanent for IANA when this document is published as an RFC. The
   string TBD, TBD1, TBD2 and TBD3 should all be replaced by the
   assigned values accordingly.

6. Security Considerations

   For general PIM-SM protocol Security Considerations, see [RFC7761].

   For general MLDP protocol Security Considerations, see [RFC6388]

   TBD

7. References

    7.1. Normative References

   [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
             Requirement Levels", BCP 14, RFC 2119, March 1997.

   [RFC5036] Andersson, L., Ed., Minei, I., Ed., and B. Thomas, Ed.,
             "LDP Specification", RFC 5036, October 2007

   [RFC5286] Atlas, A., Ed., and A. Zinin, Ed., "Basic Specification
             for IP Fast Reroute: Loop-Free Alternates", RFC 5286,
             September 2008

   [RFC5384] Boers, A., Wijnands, I., and E. Rosen, "The Protocol
             Independent Multicast (PIM) Join Attribute Format",
             RFC 5384, November 2008

   [RFC5496] Wijnands, IJ., Boers, A., and E. Rosen, "The Reverse Path
             Forwarding (RPF) Vector TLV", RFC 5496, March 2009





Liu, et al.            Expires December, 2019                [Page 11]


Internet-Draft           MoFRR based on TI-LFA                June 2019


   [RFC6388] Wijnands, IJ., Ed., Minei, I., Ed., Kompella, K., and B.
             Thomas, "Label Distribution Protocol Extensions for Point-
             to-Multipoint and Multipoint-to-Multipoint Label Switched
             Paths", RFC 6388, November 2011

   [RFC7431] Karan, A., Filsfils, C., Wijnands, IJ., Ed., and B.
             Decraene, "Multicast-Only Fast Reroute", RFC 7431, August
             2015

   [RFC7490] Bryant, S., Filsfils, C., Previdi, S., Shand, M., and N.
             So, "Remote Loop-Free Alternate (LFA) Fast Reroute (FRR)",
             RFC 7490, April 2015

   [RFC7761] Fenner, B., Handley, M., Holbrook, H., Kouvelas,
             I.,Parekh, R., Zhang, Z., and L. Zheng, "Protocol
             IndependentMulticast - Sparse Mode (PIM-SM): Protocol
             Specification(Revised)", RFC 7761, March 2016

   [RFC7891] Asghar, J., Wijnands, IJ., Ed., Krishnaswamy, S., Karan,
             A., and V. Arya, "Explicit Reverse Path Forwarding (RPF)
             Vector", RFC 7891, June 2016

   [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
             2119 Key Words", BCP 14, RFC 8174, May 2017

   [I-D.ietf-rtgwg-segment-routing-ti-lfa] Litkowski, S., Bashandy, A.,
             Filsfils, C., Decraene, B., Francois, P., Voyer, D., Clad,
             F., and P. Camarillo, "Topology Independent Fast Reroute
             using Segment Routing", draft-ietf-rtgwg-segment-routing-
             ti-lfa-01 (work in progress), March 2019


    7.2. Informative References

   TBD

8. Acknowledgments

   The authors would like to thank the following for their valuable
   contributions of this document:

   TBD




Liu, et al.            Expires December, 2019                [Page 12]


Internet-Draft           MoFRR based on TI-LFA                June 2019


   Authors' Addresses

   Yisong Liu
   Huawei Technologies
   Huawei Bld., No.156 Beiqing Rd.
   Beijing  100095
   China

   Email: liuyisong@huawei.com









































Liu, et al.            Expires December, 2019                [Page 13]


Html markup produced by rfcmarkup 1.129d, available from https://tools.ietf.org/tools/rfcmarkup/