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PFM-SD extension for EVPN multi-homing
draft-mankamana-pim-pfm-sd-extension-evpn-mh-01

Document Type Active Internet-Draft (individual)
Authors Mankamana Prasad Mishra , IJsbrand Wijnands , Ryan R Tucker , Hooman Bidgoli , Zhaohui (Jeffrey) Zhang
Last updated 2024-10-20
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draft-mankamana-pim-pfm-sd-extension-evpn-mh-01
PIM Working Group                                              M. Mishra
Internet-Draft                                                     Cisco
Intended status: Standards Track                             I. Wijnands
Expires: 23 April 2025                                        Individual
                                                               R. Tucker
                                                                 Charter
                                                              H. Bidgoli
                                                                   Nokia
                                                                Z. Zhang
                                                        Juniper Networks
                                                         20 October 2024

                 PFM-SD extension for EVPN multi-homing
            draft-mankamana-pim-pfm-sd-extension-evpn-mh-01

Abstract

   Ethernet Virtual Private Network (EVPN) solution is becoming
   pervasive in data center (DC) applications for Network Virtualization
   Overlay (NVO) and DC interconnect (DCI) services and in service
   provider (SP) applications for next-generation virtual private LAN
   services.

   EVPN defines sets of procedures to achieve multihoming between peers.
   When the multicast source is protected by EVPN multihoming for
   redundancy and multicast receivers are present behind PIM network,
   there are cases where traffic blackholes.

   PIM Flooding Mechanism (PFM) and Source Discovery (SD) define new
   flood mechanisms in PIM domain to carry information about source and
   group.  This draft defines the necessary extension to PFM-SD
   procedures to have seamless integration with EVPN supported
   multihoming.

Requirements Language

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
   "OPTIONAL" in this document are to be interpreted as described in BCP
   14 [RFC2119] [RFC8174] when, and only when, they appear in all
   capitals, as shown here.

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

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   This Internet-Draft will expire on 23 April 2025.

Copyright Notice

   Copyright (c) 2024 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
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   Please review these documents carefully, as they describe your rights
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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
   2.  Requirements Language . . . . . . . . . . . . . . . . . . . .   4
   3.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   4
   4.  Problem Statement . . . . . . . . . . . . . . . . . . . . . .   4
   5.  Solution Requirement  . . . . . . . . . . . . . . . . . . . .   6
   6.  Solution overview . . . . . . . . . . . . . . . . . . . . . .   7
     6.1.  Flooding multihome source . . . . . . . . . . . . . . . .   7
     6.2.  Optimization multihome source flooding  . . . . . . . . .   7
   7.  Security Considerations . . . . . . . . . . . . . . . . . . .   7
   8.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   7
   9.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   7
     9.1.  Normative References  . . . . . . . . . . . . . . . . . .   7
     9.2.  Informative References  . . . . . . . . . . . . . . . . .   8
   Appendix A.  Acknowledgments  . . . . . . . . . . . . . . . . . .   8
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   8

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1.  Introduction

   [RFC7432] describes procedures for BGP MPLS-based Ethernet VPNs
   (EVPN).  It defines the function, procedure, and associated BGP
   routes used to support multihoming in EVPN.  It defines the concept
   of Ethernet Segment (ES) which is a virtual construct to drive BGP
   procedures to be able to determine if two provider edge are
   multihomed.

                      +--------------+                 +-------------+
                      |              |                 |             |
                      |     PE1      |                 |    PE2      |
                      |              |                 |             |
                      +---------+----+                 +-----+-------+
                                 \                          /
                                  \                        /
                                   \                      /
                                    \                    /
                                     \                  /
                                    +-\----------------/-+
                                    |  \              /  |
                                    +---\------------/---+
                                         \          /
                                          \        /
                                        +-------------+
                                        |             |
                                        |      CE     |
                                        +-------------+

   The above figure shows a sample multihoming case. where two
   independent PE (Provider Edge) are connected to CE (customer edge)
   devices via MC-LAG.  Any packets that are originating from CE or host
   attached to CE can be hashed to either of the PE. and PE would have
   no knowledge about who can get any packets.

   [RFC8364] defines a generic flooding mechanism for distributing
   information throughout a PIM domain.

   Many deployments do use EVPN multihoming to achieve redundancy of
   reachability in the network.  When EVPN multihoming is deployed with
   PIM [RFC7761] network, there is challenge with respect to RPF
   selection by PIM domain.  This draft defines a necessary extension to
   [RFC8364] to achieve optimal multicast forwarding in PIM domain.

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2.  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.

3.  Terminology

   BD:  test

4.  Problem Statement

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                          Multicast Receiver
                                    |
                                    |
                                    | PIM (1 .1.1.1, 232.1.1.1)
                                    |
                                    |
                            +---------------+
                            |       P2      |
                            |               |
                            +---------------+
                                    |
     PIM join (10.1.1.1, 232.1.1.1) |
                                    |    Unicast Rechability
                            +--------------+  Prefix 10.1.1.0/24
                            |       P1     |  NH : PE1, PE2 (ECMP)
                            |              |
                            +--------------+
                                    /\
                                   /  \
                                  /    \
                                 /      \ PIM (10.1.1.1, 232.1.1.1)
                                /        \
                               /          \
                              /            \
                             -              -
                   +-------------+        +-------------+
                   |     PE1     |        |    PE2      |
                   |             |        |             |
 IRB 10.1.1.0/24   +-------------+        +-------------+IRB 10.1.1.0/24
                           \                     /
                            \                   /
                             \                 /
                              \               /
                               \             /
                                \           /
                                 -         -
                           +--------------------+
                           |          CE        |
                           |                    |
                           +--------------------+
                                      |
                                      |
                                      |
                                Source 10.1.1.1

   Above figure shows sample topology where

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   *  CE is multihomed to PE1 and PE2

   *  EVPN gets terminated over IRB in both of the PE

   *  North of the PE is PIM domain

   *  Multicast receiver originates PIM join towards source

   In the above topology, the source prefix is announced in IGP from
   both of the PE.  When P1 does process PIM joins towards source
   10.1.1.1, it needs to do a source prefix lookup to pick RPF towards
   the source.  Since there is ECMP path, it gets two next hop as PE1
   and PE2.  Based on local decision P1 can send PIM join to either of
   the next hop.  Consider in this case it picks PE2 as RPF to send PIM
   join.  At this point of time end to end PIM tree has been created
   where the tree is built rooted at PE2.  At present there is no data
   traffic being sourced.

   As the next step Source starts sending multicast traffic.  Once
   traffic reaches CE, it is going to hash the flow to either of the
   ports. and consider it picks PE1 as the next hop to send traffic to.

   Previous two steps (PIM join and multicast data flow) can happen in
   any order

   At the end we are in a situation where multicast traffic is being
   received by PE1 and PIM join landed on PE2 causing traffic
   blackholing.

   At present deployment uses EVPN BUM tunnel to bridge multicast
   traffic between peers.  Which results in traffic from PE1 being
   bridged to PE2 via P1. and it leads same traffic going over the link
   twice (once as bridge copy and once as routed copy).

5.  Solution Requirement

   *  It MUST avoid traffic duplication between peers unless there are
      local receivers

   *  It MUST be applicable for PIM-SM and PIM-SSM

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6.  Solution overview

   [[RFC8364] defines a generic flooding mechanism for distributing
   information throughout the PIM domain.  Multicast source discovery
   was one of the types of information being flooded in the PIM domain.
   [RFC8364] was mainly designed to flood source information for PIM-SM
   sources.  However, this draft provides an extension to flood PIM-SM
   and PIM-SSM source information if the source is being hosted in a
   multihomed port.

6.1.  Flooding multihome source

   Multihome source flood will use a generic flood mechanism defined by
   [RFC8364].  Forwarding rules are identical to [RFC8364]

   Details of TLV extension and packet format are to be added in the
   next revision.

6.2.  Optimization multihome source flooding

   TBD

7.  Security Considerations

8.  IANA Considerations

9.  References

9.1.  Normative References

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119,
              DOI 10.17487/RFC2119, March 1997,
              <https://www.rfc-editor.org/info/rfc2119>.

   [RFC7432]  Sajassi, A., Ed., Aggarwal, R., Bitar, N., Isaac, A.,
              Uttaro, J., Drake, J., and W. Henderickx, "BGP MPLS-Based
              Ethernet VPN", RFC 7432, DOI 10.17487/RFC7432, February
              2015, <https://www.rfc-editor.org/info/rfc7432>.

   [RFC7761]  Fenner, B., Handley, M., Holbrook, H., Kouvelas, I.,
              Parekh, R., Zhang, Z., and L. Zheng, "Protocol Independent
              Multicast - Sparse Mode (PIM-SM): Protocol Specification
              (Revised)", STD 83, RFC 7761, DOI 10.17487/RFC7761, March
              2016, <https://www.rfc-editor.org/info/rfc7761>.

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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>.

   [RFC8364]  Wijnands, IJ., Venaas, S., Brig, M., and A. Jonasson, "PIM
              Flooding Mechanism (PFM) and Source Discovery (SD)",
              RFC 8364, DOI 10.17487/RFC8364, March 2018,
              <https://www.rfc-editor.org/info/rfc8364>.

9.2.  Informative References

Appendix A.  Acknowledgments

Authors' Addresses

   Mankamana Mishra
   Cisco
   Email: mankamis@cisco.com

   IJsbrand Wijnands
   Individual
   Email: ice@braindump.be

   Ryan R Tucker
   Charter
   Email: Ryan.Tucker@charter.com

   Hooman Bidgoli
   Nokia
   Email: hooman.bidgoli@nokia.com

   Zhaohui Zhang
   Juniper Networks
   Email: zzhang@juniper.net

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