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Versions: (draft-ramki-pim-null-register-packing) 00

Network Working Group                                          V. Kamath
Internet-Draft                                                    VMware
Intended status: Standards Track            R. Chokkanathapuram Sundaram
Expires: April 22, 2019                              Cisco Systems, Inc.
                                                        October 19, 2018


                       PIM NULL Register packing
                draft-ietf-pim-null-register-packing-00

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 carry
   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
   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 April 22, 2019.

Copyright Notice

   Copyright (c) 2018 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
   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.

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 format  . . . . . . . . . . . . . . . .   4
   4.  New Packed PIM Register Stop format . . . . . . . . . . . . .   5
   5.  Protocol operation  . . . . . . . . . . . . . . . . . . . . .   6
   6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   7
   7.  Acknowledgments . . . . . . . . . . . . . . . . . . . . . . .   7
   8.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   7
     8.1.  Normative References  . . . . . . . . . . . . . . . . . .   7
     8.2.  Informative References  . . . . . . . . . . . . . . . . .   8
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   8

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
   increase, 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 usual way since they don't check for the capability
   information present in the Register stop message.  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 2: PIM Register Stop packet 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 format

   PIM null-register packet format is enhanced to include the count of
   the number of null-register records and pack multiple null-register
   records in the same packet.  Currently the data part in the NULL
   register packet is a dummy IPv4 header which carries the source and
   group information and the other fields are unused.  To indicate that
   the null register is in a new format the "Type" field in the PIM
   register packet format is used.  To indicate the number of null
   register records a new field "record count" is introduced which can
   hold 8 bit value (max 255 records can be packed) which can be based
   on MTU.  Even though null registers are supposed to be sent exactly
   every 60s, its fine to send a null register earlier, so as to merge
   the registers.  When one register is sent, multiple registers can be
   packed together which are close enough in time.




































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   Figure 1: New PIM NULL Register packet 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  |    Reserved   |           Checksum            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      | Record 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 packed NULL Register type value TBD

      Record 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 Packed PIM Register Stop format

   The PIM register stop can be optimized to include multiple multicast
   group and source information.  The Record count can indicate the
   number of S,G records that are packed and the Type value is used to
   indicate the new format.











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   Figure 3: New PIM Packed Register Stop packet formats
       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  |  Reserved     |           Checksum            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      | Record 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 packed Register Stop type value 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 the modified Register Stop, FHR will start packing
        of NULL registers using the new packed register format (Figure 1)
     d. RP processes the NULL registers and can generate 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.  IANA Considerations

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

7.  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.

8.  References

8.1.  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>.




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8.2.  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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