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Versions: (draft-venaas-pim-hierarchicaljoinattr) 00 01 02 03 04 05 06 07 08 RFC 7887

Network Working Group                                          S. Venaas
Internet-Draft                                                 J. Arango
Updates: 5384 (if approved)                                Cisco Systems
Intended status: Standards Track                             I. Kouvelas
Expires: October 27, 2016                                Arista Networks
                                                          April 25, 2016


                   Hierarchical Join/Prune Attributes
               draft-ietf-pim-hierarchicaljoinattr-08.txt

Abstract

   This document defines a hierachical method of encoding Join
   attributes, providing a more efficient encoding when the same
   attribute values need to be specified for multiple sources in a PIM
   Join/Prune message.  This document updates RFC 5384 by renaming the
   Encoding Type registry specified there.

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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   Internet-Drafts are draft documents valid for a maximum of six months
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   This Internet-Draft will expire on October 27, 2016.

Copyright Notice

   Copyright (c) 2016 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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   include Simplified BSD License text as described in Section 4.e of



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   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Requirements Notation . . . . . . . . . . . . . . . . . . . .   3
   3.  Hierarchical Join/Prune Attribute Definition  . . . . . . . .   3
   4.  PIM Address Encoding Types  . . . . . . . . . . . . . . . . .   6
   5.  Hierarchical Join/Prune Attribute Hello Option  . . . . . . .   6
   6.  Security Considerations . . . . . . . . . . . . . . . . . . .   7
   7.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   7
   8.  Normative References  . . . . . . . . . . . . . . . . . . . .   7
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   7

1.  Introduction

   PIM Join attributes as defined in [RFC5384] allow for specifying a
   set of attributes for each of the joined or pruned sources in a PIM
   Join/Prune message.  Attributes must be separately specified for each
   individual source in the message.  However, in some cases the same
   attributes and values need to be specified for some, or even all, the
   sources in the message.  The attributes and their values then need to
   be repeated for each of the sources where they apply.

   This document provides a hierarchical way of encoding attributes and
   their values in a Join/Prune message, so that if the same attribute
   and value is to apply for all the sources, it needs only be specified
   once in the message.  Similarly, if all the sources in a specific
   group set share a specific attribute and value, it needs only be
   specified once for the entire group set.

   This document extends [RFC5384] by specifying that the encoding type
   defined there also applies to Encoded-Unicast and Encoded-Group
   formats.  This document also updates RFC 5384 by renaming the PIM
   Encoded-Source Address Encoding Type Field registry to be a PIM
   Address Encoding Type registry.  The content of the registry remains
   the same.  The encoding type used for Join attributes is however
   still limited to be used in Join/Prune messages.  Note that Join
   attributes, as they are referred to in [RFC5384], also apply to
   pruned sources in a Join/Prune message.  Thus the more correct name
   Join/Prune attributes will be used throughout the rest of this
   document.

   This document allows Join/Prune attributes to be specified in the
   Upstream Neighbor Address field, and also in the Multicast Group
   Address field, of a Join/Prune message.  It defines how this is used
   to specify the same Join/Prune attribute and value for multiple



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   sources.  This document also defines a new Hello Option to indicate
   support for the hierarchical encoding specified.

2.  Requirements Notation

   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 [RFC2119].

3.  Hierarchical Join/Prune Attribute Definition

   The format of a PIM Join/Prune message is defined in [RFC7761] as
   follows:






































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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
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |PIM Ver| Type  |   Reserved    |           Checksum            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |        Upstream Neighbor Address (Encoded-Unicast format)     |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |  Reserved     | Num groups    |          Holdtime             |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |         Multicast Group Address 1 (Encoded-Group format)      |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |   Number of Joined Sources    |   Number of Pruned Sources    |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |        Joined Source Address 1 (Encoded-Source format)        |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                             .                                 |
      |                             .                                 |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |        Joined Source Address n (Encoded-Source format)        |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |        Pruned Source Address 1 (Encoded-Source format)        |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                             .                                 |
      |                             .                                 |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |        Pruned Source Address n (Encoded-Source format)        |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                           .                                   |
      |                           .                                   |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |         Multicast Group Address m (Encoded-Group format)      |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |   Number of Joined Sources    |   Number of Pruned Sources    |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |        Joined Source Address 1 (Encoded-Source format)        |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                             .                                 |
      |                             .                                 |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |        Joined Source Address n (Encoded-Source format)        |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |        Pruned Source Address 1 (Encoded-Source format)        |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                             .                                 |
      |                             .                                 |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |        Pruned Source Address n (Encoded-Source format)        |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+



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   The message contains a single Upstream Neighbor Address, and one or
   more group sets.  Each group set contains a Group Address and two
   source lists, the Joined Sources and the Pruned Sources.  The
   Upstream Neighbor Address, the group addresses and the source
   addresses are encoded in Encoded-Unicast format, Encoded-Group format
   and Encoded-Source format, respectively.  This document extends the
   use of the source address encoding defined in [RFC5384] to also apply
   to the Upstream Neighbor Address and the Group Address fields, see
   Section 4.

   For a Join/Prune message a hierarchy of Join/Prune attributes is
   defined.  Attributes at the highest level, that is the least
   specific, apply to every source in the message.  These are encoded in
   the Upstream Neighbor Address.  Attributes at the next more specific
   level apply to every source in a group set.  They are encoded in a
   Group Address.  And finally there are attributes that apply to a
   single source, encoded in the source address as defined in [RFC5384].

   The complete set of attributes that apply to a given source is
   obtained by combining the message wide attributes, the attributes of
   the group set that the source belongs to, and the source specific
   attributes.  However, if the same attribute is specified at multiple
   levels, then the one at the most specific level overrides the other
   instances of the attribute.  Note that the set of attributes and
   their values is formed before processing the attributes.  Hence a
   value that is invalid for a given type might override a valid value
   at a higher level.

   As an example, say that for a given source we have attributes T_1
   with value V_1, T_2 with value V_2, and T_3 with value V_3.  Also
   that in the Group Address of the source's group set we have
   attributes T_1 with value V_6, and T_4 with value V_4.  And that we
   in the Upstream Neighbor Address have encoded the attributes T_1 with
   value V_7, T_4 with value V_8, and T_5 with value V_5.  The
   attributes applied to the given source will be T_1 with value V_1,
   T_2 with value V_2, T_3 with value V_3, T_4 with value V_4 and T_5
   with value V_5.  Here we have T_1 with different values at each
   level, so we use the value specified at the source level.  Also we
   have T_4 with different values at the group and message levels, so we
   use the value at the group level.  Here it could be that V_1 is not a
   valid value for T_1, but it still overrides the values at the higher
   levels as we do not process the attributes until after forming the
   set.

   Note that Join/Prune attributes are still applied to sources as
   specified in [RFC5384].  This document does not change the meaning of
   any attributes, it is simply a more compact way of encoding an
   attribute when the same attribute and value applies to multiple



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   sources.  E.g., with the example above, we would have the exact same
   meaning if we instead had encoded all the attributes T1, ..., T5 with
   the respective values V1, ..., V5 in the source address.

4.  PIM Address Encoding Types

   Addresses in PIM messages are specified together with an address
   family and an encoding type.  This applies to Encoded-Unicast,
   Encoded-Group and Encoded-Source addresses.  The encoding types allow
   the address to be encoded according to different schemes.  An
   encoding type indicates how an address is encoded irrespective of
   address type, Encoded-Unicast, Encoded-Group or Encoded-Source.  It
   is possible that there will be future encoding types that do not
   apply to all address types though.  This means that as currently
   defined, 0 is native encoding, and 1 is Join/Prune attributes
   encoding, encoded according to [RFC5384].  Note that as specified in
   [RFC5384], a type 1 Encoded Address MUST contain at least one Join/
   Prune attribute.

5.  Hierarchical Join/Prune Attribute Hello Option

   A PIM router indicates that it supports the mechanism specified in
   this document by including the Hierarchical Join/Prune Attribute
   Hello Option in its PIM Hello message.  When this new Hello Option is
   included, it MUST also include the Join-Attribute Hello option as
   specified in [RFC5384].  The format of the Hierarchical Join/Prune
   Attribute Hello Option is defined to be:

       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
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |        OptionType = TBD       |       OptionLength = 0        |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   OptionType = TBD, OptionLength = 0.  Note that there is no option
   value included.

   A PIM router MUST NOT send a Join/Prune message with Join/Prune
   attributes encoded in the Upstream Neighbor Address or any of the
   group addresses out any interface on which there is a PIM neighbor
   that has not included this option in its Hellos.  Even a router that
   is not the upstream neighbor must be able to parse the message in
   order to perform Join suppression and Prune override.








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6.  Security Considerations

   This document specifies a more compact encoding of Join/Prune
   attributes.  Use of the encoding has no impact on security aside from
   using the encoding in [RFC5384].  For instance an attack with a
   forged message with certain attribute values is equally difficult
   independent of which encoding is used.  If an attribute that applies
   to the entire message is wrong, then that may cause an issue for all
   the sources in the message.  But without this encoding, one would
   instead include that attribute for every single source, and that
   would also cause an issue for all the sources in the message.

7.  IANA Considerations

   The current PIM Encoded-Source Address Encoding Type Field registry
   needs to be renamed to a PIM Address Encoding Type registry.  The
   content of the registry remains the same.  The Hierarchical Join/
   Prune Attribute Hello Option needs to be added to the PIM-Hello
   Options registry, and TBD above must be replaced by the assigned
   value.

8.  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,
              <http://www.rfc-editor.org/info/rfc2119>.

   [RFC5384]  Boers, A., Wijnands, I., and E. Rosen, "The Protocol
              Independent Multicast (PIM) Join Attribute Format",
              RFC 5384, DOI 10.17487/RFC5384, November 2008,
              <http://www.rfc-editor.org/info/rfc5384>.

   [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, <http://www.rfc-editor.org/info/rfc7761>.

Authors' Addresses

   Stig Venaas
   Cisco Systems
   Tasman Drive
   San Jose, CA  95134
   USA

   Email: stig@cisco.com



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   Jesus Arango
   Cisco Systems
   Tasman Drive
   San Jose, CA  95134
   USA

   Email: jearango@cisco.com


   Isidor Kouvelas
   Arista Networks
   5453 Great America Parkway
   Santa Clara, CA  95054
   USA

   Email: kouvelas@arista.com



































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