Internet DRAFT - draft-venaas-pim-pfm-sd-subtlv

draft-venaas-pim-pfm-sd-subtlv







Network Working Group                                          S. Venaas
Internet-Draft                                       Cisco Systems, Inc.
Intended status: Experimental                                     F. Meo
Expires: 5 September 2024                                   4 March 2024


          PIM Flooding Mechanism and Source Discovery Sub-TLV
                   draft-venaas-pim-pfm-sd-subtlv-01

Abstract

   PIM Flooding Mechanism and Source Discovery (RFC 8364) allows for
   announcement of active sources, but it does not allow for providing
   additional information about the flow.  This document defines a new
   TLV for announcing sources that allows for Sub-TLVs that can be used
   for providing various types of information.  This document defines a
   Sub-TLV for flow data rate.

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 5 September 2024.

Copyright Notice

   Copyright (c) 2024 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

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   provided without warranty as described in the Revised BSD License.



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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Conventions Used in This Document . . . . . . . . . . . . . .   2
   3.  Group Source Holdtime Info TLV  . . . . . . . . . . . . . . .   2
   4.  Group Source Holdtime Info Flow data rate Sub-TLV . . . . . .   4
   5.  Security Considerations . . . . . . . . . . . . . . . . . . .   5
   6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   5
   7.  Normative References  . . . . . . . . . . . . . . . . . . . .   5
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   6

1.  Introduction

   It may be useful to provide additional information about flows in PFM
   [RFC8364] source announcements.  One such case is flow data rate.
   Routers may use this information in various ways, for instance to
   decide whether there is sufficient available bandwidth to join the
   tree or in case of ECMP, selecting an interface that has sufficient
   available bandwidth.

   This document defines a new TLV for announcing sources that allows
   for Sub-TLVs that can be used providing various types of information.
   It also defines a Sub-TLV for flow data rate.

2.  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].

3.  Group Source Holdtime Info TLV

   PFM-SD [RFC8364] defines a Group Source Holdtime (GSH) TLV for
   announcing active sources.  This document defins a new Group Source
   Holdtime Info (GSHI) TLV that is used similarly to the GSH TLV except
   that it only provides info for a single source, and includes
   additional information about the flow in Sub-TLVs.














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       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
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |T|         Type = TBD            |          Length             |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |              Group Address (Encoded-Group format)             |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |             Src Address 1 (Encoded-Unicast format)            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |        Src Holdtime           |        Type Sub-TLV 1         |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |       Length Sub-TLV 1        |       Value Sub-TLV 1         |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+                               +
      |                               .                               |
      |                               .                               |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                               .                               |
      |                               .                               |
      |        Type Sub-TLV n         |       Length Sub-TLV n        |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |        Value Sub-TLV n
      |                               .                               |
      |                               .                               |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   T:  If the Transitive bit is set to 0, a router MUST NOT forward the
      message unless it supports this TLV and all the Sub-TLVs that are
      present in the TLV in this message.  If the transitive bit is set
      to 1, it is forwarded even if the router does not support the TLV
      or all the Sub-TLVs present.

   Type:  This TLV has type TBD.

   Length:  The length of the value in octets.

   Group Address:  The group that sources are to be announced for.  The
      format for this address is given in the Encoded-Group format in
      [RFC7761].

   Src Address:  The source address for the corresponding group.  The
      format for these addresses is given in the Encoded-Unicast address
      in [RFC7761].

   Src Holdtime:  The Holdtime (in seconds) for the included source(s).

   Type Sub-TLV 1..n:  The TLV contains n Sub-TLVs, n MAY be 0.  The





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      total length of the TLV (the Length field) is used to derive the
      how many octets are used for Sub-TLVs.  It will be at least 4 * n
      octets if n Sub-TLVs are present.  Type Sub-TLV indicates the type
      of the Sub-TLV.  The allowed types are Sub-TLV types that are
      specifically defined for use in the Group Source Holdtime Info
      TLV.  This document defines one such Sub-TLV type.

   Length Sub-TLV 1..n:  The length of the Sub-TLV Value field in
      octets.

   Value Sub-TLV 1..n:  The value of the Sub-TLV associated with the
      type and of the specified length.

4.  Group Source Holdtime Info Flow data rate Sub-TLV

       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
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |         Type = TBD            |          Length = 2           |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      | Exponent  |    Significand    |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Type:  This TLV has type TBD.

   Length:  The length of the value in octets.  The length is always 2.

   Exponent and Significand:  The value of the TLV contains Exponent and
      Significand, each is 1 octet.  These are used to indicate the flow
      data rate as specified below.

   The data rate of a flow is specified using the Exponent and
   Significand fields.  The rate is Significand * 10 ^ Exponent kbps.
   This allows specifying the rate with up to 3 decimal digits precision
   and speeds from 1 kbps to 10 ^ 67 kbps.  A computed speed of 0 kbps
   means the rate is less than 1 kbps.

   Here are some examples of how this is used:

               Link Speed     Exponent     Significand
              ------------   ----------   -------------
               500 kbps       0            500
               500 kbps       2              5
               155 Mbps       3            155
                40 Gpbs       6             40
               100 Gpbs       6            100
               100 Gpbs       8              1




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5.  Security Considerations

   When it comes to general PIM message security, see [RFC7761].  For
   PFM security see [RFC8364].

   This document defines a new format allowing for additional flow
   information.  One concern is what happens if wrong information is
   provided by accident, or intentionally in a sppofed message by an
   attacker.  The impact depends on what information is provided.

   This document defines a Sub-TLV for flow data rate.  If the rate
   provided is not correct, a router may make decisions using the wrong
   rate.  If the rate indicated is too high, a router may for instance
   decide not to join assuming there is not sufficient bandwidth
   available.  If it is too low, the router may join even if there is
   not sufficient bandwidth, causing packet drops.

6.  IANA Considerations

   This document requires the assignment of a new PFM TLV type in the
   "PIM Flooding Mechanism Message Types" registry.  Also, a new
   registry "PFM Group Source Holdtime Info Sub-Types" registry needs to
   be created.  Assignments for the new registry are to be made
   according to the policy "IETF Review" as defined in [RFC8126].  The
   initial content of the registry should be:

    Sub-Type         Name                  Reference
   ------------------------------------------------------
        0        Reserved               [this document]
        1        Flow data rate         [this document]
     2-32767     Unassigned

7.  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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   [RFC8126]  Cotton, M., Leiba, B., and T. Narten, "Guidelines for
              Writing an IANA Considerations Section in RFCs", BCP 26,
              RFC 8126, DOI 10.17487/RFC8126, June 2017,
              <https://www.rfc-editor.org/info/rfc8126>.

   [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>.

Authors' Addresses

   Stig Venaas
   Cisco Systems, Inc.
   Tasman Drive
   San Jose,  CA 95134
   United States of America
   Email: stig@cisco.com


   Francesco Meo
   Email: fran.meo@gmail.com





























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