Internet DRAFT - draft-venaas-pim-hierarchicaljoinattr
draft-venaas-pim-hierarchicaljoinattr
Network Working Group S. Venaas
Internet-Draft I. Kouvelas
Updates: 5384 (if approved) J. Arango
Intended status: Standards Track Cisco Systems
Expires: August 10, 2013 February 6, 2013
Hierarchical Join/Prune Attributes
draft-venaas-pim-hierarchicaljoinattr-00.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.
Status of this Memo
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Requirements Notation . . . . . . . . . . . . . . . . . . . . 4
3. Hierarchical Join/Prune Attribute Definition . . . . . . . . . 5
4. PIM Address Encoding Types . . . . . . . . . . . . . . . . . . 8
5. Hierarchical Join/Prune Attribute Hello Option . . . . . . . . 9
6. Security Considerations . . . . . . . . . . . . . . . . . . . 10
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 11
8. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 12
9. Normative References . . . . . . . . . . . . . . . . . . . . . 13
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 14
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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 updates [RFC5384] which defines an encoding to be used
for Encoded-Source Addresses. This document extends this by
specifying the same encoding type also for Encoded-Unicast and
Encoded-Group formats. This document defines a new IANA registry for
PIM encoding types which is to be used for all the fields in PIM
messages where encoding types are used, replacing the old registry
that is specific to Encoded-Source Addresses. 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
sources. This document also introduces a new Hello Option to
indicate support for the hierarchical encoding specified.
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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].
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3. Hierarchical Join/Prune Attribute Definition
The format of a PIM Join/Prune message is defined in [RFC4601] 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 all encoded in Encoded-Unicast format, Encoded-Group
format and Encoded-Source format, respectively. In this document we
make use of this to allow Join/Prune attributes in each of these
addresses, using the encoding in Section 4.
For a Join/Prune message we define a hierarchy of Join/Prune
attributes. At the highest level, that is the least specific, we
have attributes that apply to every source in the message. These are
encoded in the Upstream Neighbor Address. At the next more specific
level we have attributes that apply to every source in a group set.
They are encoded in a Group Address. And finally at the most
specific level, we have attributes that just 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 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
sources.
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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. While it
is possible to have the same encoding type value indicate different
encodings depending on whether it is a Unicast, Group or Source
address, it is simpler to have the same encoding type value indicate
the same encoding independent of where it is used. This means that
as currently defined, 0 means a native encoding, and 1 means there
are Join/Prune attributes, encoded according to [RFC5384]. Even if
the encoding type space is shared between the different address types
(Encoded-Unicast, Encoded-Group and Encoded-Source), one could have a
specific encoding apply to a specific address type if needed.
The current IANA PIM Encoded-Source Address Encoding Type Field
registry should be changed into a PIM Address Encoding Type registry.
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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. Note that it also needs to
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 do Join suppression or Prune overriding.
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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.
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7. IANA Considerations
The current PIM Encoded-Source Address Encoding Type Field registry
should be changed into a PIM Address Encoding Type registry. The
only required change is the name of the registry. The contents
remain the same.
A new PIM Hello Option type needs to be assigned. The string TBD
needs to be replaced with the permanently assigned value.
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8. Acknowledgments
Acknowledgments to be added.
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9. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC4601] Fenner, B., Handley, M., Holbrook, H., and I. Kouvelas,
"Protocol Independent Multicast - Sparse Mode (PIM-SM):
Protocol Specification (Revised)", RFC 4601, August 2006.
[RFC5384] Boers, A., Wijnands, I., and E. Rosen, "The Protocol
Independent Multicast (PIM) Join Attribute Format",
RFC 5384, November 2008.
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Authors' Addresses
Stig Venaas
Cisco Systems
Tasman Drive
San Jose, CA 95134
USA
Email: stig@cisco.com
Isidor Kouvelas
Cisco Systems
Tasman Drive
San Jose, CA 95134
USA
Email: kouvelas@cisco.com
Jesus Arango
Cisco Systems
Tasman Drive
San Jose, CA 95134
USA
Email: jearango@cisco.com
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