PIM Null register packing
draft-ietf-pim-null-register-packing-04

Versions: 00 01 02 03 04                                                
Network Working Group                                          V. Kamath
Internet-Draft                                                    VMware
Intended status: Standards Track            R. Chokkanathapuram Sundaram
Expires: September 12, 2019                          Cisco Systems, Inc.
                                                          March 11, 2019


                       PIM Null register packing
                draft-ietf-pim-null-register-packing-02

Abstract

   In PIM-SM networks PIM registers are sent from the first hop router
   to the RP (Rendezvous Point) to signal the presence of Multicast
   source in the network.  There are periodic PIM Null registers sent
   from first hop router to the RP to keep the state alive at the RP as
   long as the source is active.  The PIM Null register packet carries
   information about a single Multicast source and group.  This document
   defines a standard to send multiple Multicast source and group
   information in a single pim Null register packet and the
   interoperability between the PIM routers which do not understand the
   packet format with multiple Multicast source and group details.

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
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   This Internet-Draft will expire on September 12, 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
   (https://trustee.ietf.org/license-info) in effect on the date of



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   publication of this document.  Please review these documents
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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
     1.1.  Conventions Used in This Document . . . . . . . . . . . .   2
     1.2.  Terminology . . . . . . . . . . . . . . . . . . . . . . .   3
   2.  PIM Register Stop format with capability option . . . . . . .   3
   3.  New PIM Null register message . . . . . . . . . . . . . . . .   4
   4.  New PIM Register Stop message format  . . . . . . . . . . . .   4
   5.  Protocol operation  . . . . . . . . . . . . . . . . . . . . .   5
   6.  PIM Anycast RP considerations . . . . . . . . . . . . . . . .   6
   7.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   6
   8.  Acknowledgments . . . . . . . . . . . . . . . . . . . . . . .   6
   9.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   6
     9.1.  Normative References  . . . . . . . . . . . . . . . . . .   7
     9.2.  Informative References  . . . . . . . . . . . . . . . . .   7
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   7

1.  Introduction

   PIM Null registers are sent by First hop routers periodically for
   Multicast streams to keep the states active on the RP as long as the
   Multicast source is alive.  As the number of multicast sources
   increases, the number of PIM Null register packets that are sent
   increases at a given time.  This results in more PIM packet
   processing at RP and FHR.  The control plane policing (COPP),
   monitors the packets that gets processed by the control plane.  Due
   to the high rate at which Null registers are received at the RP, this
   can lead to COPP drops of Multicast PIM Null register packets.  This
   draft proposes a method to efficiently pack multiple PIM Null
   registers and register stop into a single message as these packets
   anyway don't contain data.  The draft also proposes interoperability
   with the routers that do not understand the new packet format.

1.1.  Conventions Used in This Document

   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 RFC 2119 [RFC2119].






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1.2.  Terminology

   RP:  Rendezvous Point

   RPF:  Reverse Path Forwarding

   SPT:  Shortest Path Tree

   FHR:  First Hop Router, directly connected to the source

   LHR:  Last Hop Router, directly connected to the receiver

2.  PIM Register Stop format with capability option

   A router (FHR) can decide to pack multiple Null registers based on
   the capability received from the RP as part of Register Stop.  This
   ensures compatibility with routers that don't support processing of
   the new format.  The capability information can be indicated by the
   RP via the PIM register stop message sent to the FHR.  Thus a FHR
   will switch to the new format only when it learns RP is capable of
   handling the packed Null register messages.  Conversely, a FHR that
   doesn't support the new format can continue generating the PIM Null
   register the current way.  To exchange the capability information in
   the Register Stop message, the "reserved" field can be used to
   indicate this capability in those register stop messages.  One bit of
   the reserved field is used to indicate the "packing" capability (P
   bit).  The rest of the bits in the "Reserved" field will be retained
   for future use.

   Figure 1: PIM Register Stop message with capability option

    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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |PIM Ver| Type  |P|  Reserved   |           Checksum            |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |             Group Address (Encoded-Group format)              |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |            Source Address (Encoded-Unicast format)            |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   PIM Version, Reserved, Type, Checksum, Group Address, Source Address
       Same as RFC 7761 (Section 4.9.4)

   P   Capability bit used to indicate support for Packed Null Register






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3.  New PIM Null register message

   New PIM Null register message format includes a count to indicate the
   number of Null register records in the message.

   Figure 2: New PIM Null Register message format
       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
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |PIM Ver| Type  |SubType| Rsvd  |           Checksum            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |   count       |              Reserved2                        |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |     Group Address[1]  (Encoded-Group format)                  |
      |     Source Address[1]  (Encoded-Unicast format)               |
      .                                                               .
      .                                                               .
      .                                                               .
      .                                                               .
      .     Group Address[N]                                          .
      |     Source Address[N]                                         |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

      PIM Version, Reserved, Checksum
          Same as RFC 7761 (Section 4.9.3)

      Type, SubType
          The new packed Null Register Type and SubType values TBD

      count
          The count of the number of packed Null register records.
          A record consists of Group and Source Address

      Group Address
          IP address of the Multicast Group

      Source Address
          IP Address of the Multicast Source

4.  New PIM Register Stop message format

   The new PIM register stop is message includes a count to indicate the
   number of records that are present in the message.








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   Figure 3: New PIM Register Stop message format
       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
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |PIM Ver| Type  |SubType| Rsvd  |           Checksum            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |     count     |          Reserved2                            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |     Group Address[1]  (Encoded-Group format)                  |
      |     Source Address[1]  (Encoded-Unicast format)               |
      .                                                               .
      .                                                               .
      .                                                               .
      .                                                               .
      .     Group Address[N]                                          .
      |     Source Address[N]                                         |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

      PIM Version, Reserved, Checksum
          Same as RFC 7761 (Section 4.9.3)

      Type
          The new Register Stop Type and SubType values TBD

      Record count
          The count of the number of packed register stop records.
          A record consists of Group and Source Address

      Group Address
          IP address of the Multicast Group

      Source Address
          IP Address of the Multicast Source


5.  Protocol operation















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   The following combinations exist -
   FHR and RP both support the new PIM Register formats -
     a. FHR sends the PIM register towards the RP when a new source is
        detected
     b. RP sends a modified register stop towards the FHR that includes
        capability
        information by setting the P bit (Figure 2)
     c. Based on the receipt of new Register Stop, FHR will
        start packing of Null registers using the new packed register
        format (Figure 1)
     d. RP processes the new Null register message and can generate new
        register Stop messages by packing multiple S,Gs towards the same
        FHR (Figure 3)

   FHR supports but RP doesn't support new PIM Register formats-
     a. FHR sends the PIM register towards the RP
     b. RP sends a normal register stop without any capability
        information
     c. FHR then sends Null registers in the old format

   RP supports but FHR doesn't support the new PIM Register formats-
     a. FHR sends the PIM register towards the RP
     b. RP sends a modified register stop towards the FHR that includes
        capability information
     c. Since FHR doesn't support the new format, it sends Null
        registers in the old format

6.  PIM Anycast RP considerations

   The new PIM register format should be enabled only if its supported
   by all PIM anycast RP members in the RP set for the RP address.

7.  IANA Considerations

   This document requires the assignment of 2 new PIM message types for
   the packed pim register and pim register stop.

8.  Acknowledgments

   The authors would like to thank Stig Venaas and Umesh Dudani for
   contributing to the original idea and also their very helpful
   comments on the draft.

9.  References







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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>.

   [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>.

9.2.  Informative References

   [RFC3973]  Adams, A., Nicholas, J., and W. Siadak, "Protocol
              Independent Multicast - Dense Mode (PIM-DM): Protocol
              Specification (Revised)", RFC 3973, DOI 10.17487/RFC3973,
              January 2005, <https://www.rfc-editor.org/info/rfc3973>.

Authors' Addresses

   Vikas Ramesh Kamath
   VMware
   3401 Hillview Ave
   Palo Alto  CA 94304
   USA

   Email: vkamath@vmware.com


   Ramakrishnan Chokkanathapuram Sundaram
   Cisco Systems, Inc.
   Tasman Drive
   San Jose  CA 95134
   USA

   Email: ramaksun@cisco.com













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