Internet Draft R. Atkinson
draft-rja-ilnp-icmp-00.txt Extreme Networks
Category: Experimental
Expires: 10 June 2009 10 December 2008
ICMP Locator Update message
draft-rja-ilnp-icmp-00.txt
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This document is a contribution to the IRTF Routing Research Group.
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Abstract
This describes an experimental ICMPv6 message type to dynamically
update Identifier/Locator bindings for an Identifier Locator
Network Protocol based upon IPv6.
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Table of Contents
1. Introduction ...........................................2
2. Syntax..................................................3
3. Transport Protocol Effects..............................4
4. Backwards Compatibility.................................4
5. Security Considerations ................................5
6. IANA Considerations ....................................5
7. References .............................................6
1. Introduction
At present, the IRTF Routing Research Group is studying different
approaches to evolving the Internet Architecture.
Several different classes of evolution are being considered. One
class is often called "Map and Encapsulate", where traffic would be
mapped and then tunnelled through the inter-domain core of the
Internet. Another class being considered is sometimes known as
"Identifier/Locator Split". This document relates to a proposal that
is in the latter class of evoluationary approaches. In particular,
the Identifier-Locator Network Protocol being described in this
document and related Internet-Drafts is an evolution of IPv6. [ILNP-
Intro] [ILNP-Nonce] [ILNP-DNS] [RFC-2460]
The new ICMPv6 Locator Update message described in this document
enables an enhanced node to update its correspondents about the
currently valid set of Locators valid for use to reaching the node
sending this message.
This new ICMPv6 message must not be used for IP sessions operating in
classic IPv6 mode; it must only be used for IP sessions that are
operating in Identifier/Locator Split mode.
2. Syntax
------------------------------------------------------------
| ICMP Type | ICMP Code | Checksum |
+-------------+---------------+-------------+--------------+
| Num of Locs | RESERVED FOR FUTURE USE |
+-------------+---------------+-------------+--------------+
/ Locator /
+-------------+---------------+-------------+--------------+
ICMP Type: This 8-bit field is set to a value that
indicates this is a Locator Update message.
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ICMP Code: This 8-bit field indicates which kind of
ICMP Locator Update this is. At present,
the only valid value is 0, which means
that this message contains all currently
valid Locator values for the sending node.
Checksum: This contains the ICMPv6 Checksum value
for this packet.
Num of Locs: This field contains the number of 64-bit
Locators that follow the RESERVED field.
This field must not contain the number zero,
as each ILNP node needs to be reachable via
at least 1 Locator value. Multi-homed nodes
will have at least 2 Locator values.
Reserved: This 24-bit field must be sent as zero.
At this time, recipients should ignore the
contents of this field, as these bits are
reserved for future use.
Locator: This 64-bit field contains a valid Locator
that can be used to reach the sending node.
A variable number of Locator fields are
concatenated one after another. These are
listed in priority order, with the first
Locator field containing the most preferred
Locator value.
3. Transport Protocol Effects
This message has no impact on any transport protocol.
The message may affect where packets for a given transport
session are sent, but one of the design objectives for the
I/L Split Mode (ILNP) is to decouple transport-protocols
from network-layer changes.
4. Implementation Considerations
Implementers may use any internal implementation they wish,
provided that the external appearance is the same as this
implementation approach.
To support the Identifier/Locator Split operating mode, and
retain the incremental deployability and backwards compatibility
needed, the network layer needs a mode bit in the Transport Control
Block (or its equivalent) to track which IP sessions are using
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the classic IPv6 mode and which IP sessions are using the
Identifier/Locator Split mode.
Further, when in the Identifier/Locator Split mode, nodes will
need to retain a Correspondent Cache in the network layer that
contains for each correspondent node:
- Source Identifier(s) in use
- Source Locator(s) in use
- Destination Identifier(s) in use
- Destination Locator(s) in use
- Session Nonce value from Local Node to Correspondent Node
- Session Nonce value from Correspondent Node to Local Node
5. Backwards Compatibility
For all sessions operating in Identifier/Locator Split mode,
inside each node the high-order 64-bits ("Locator") are always
set to zero before the packet is sent upwards to the transport
protocol. So any changes in Locator values used on the wire
will be invisible to the transport protocol. In this mode,
transport-layer checksums (e.g. TCP pseudo-header checksum)
will be calculated with both Source Locator and Destination
Locator fields set to all zero.
For nodes or sessions not operating in Identifier/Locator Split
mode, the ICMP Locator Update packet must be discarded
by the recipient without being processed.
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6. Security Considerations
The ICMP Locator Update message must only be used for IP sessions
operating in the Identifier/Locator Split mode.
The experimental Nonce Destination Option [ILNP-Nonce] must be
present in packets containing an ICMPv6 Locator Update message.
Further, the received Nonce Destination Option must contain the
correct nonce value for the packet to be accepted by the recipient
and then passed to the ICMPv6 protocol for processing.
[ Copy some text from -ilnp-intro's Security Considerations to here ]
For sessions operating in higher risk environments, the use
of the IP Authentication Header *in addition* to the experimental
Nonce Destination Option is recommended.
7. IANA Considerations
(To be written later)
8. References
8.1. Normative References
[RFC-2119] Bradner, S., "Key words for use in RFCs to
Indicate Requirement Levels", BCP 14, RFC 2119,
March 1997.
[RFC-2460] S. Deering & R. Hinden, "Internet Protocol
Version 6 Specification", RFC-2460,
December 1998.
8.2. Informative References
[ILNP-Intro] Atkinson, R, "ILNP Concept of Operations",
draft-rja-ilnp-intro-01.txt, June 2008.
[ILNP-DNS] Atkinson, R, "Additional DNS Resource Records",
draft-rja-ilnp-dns-00.txt, June 2008.
[ILNP-Nonce] Atkinson, R, "Nonce Destination Option",
draft-rja-ilnp-nonce-00.txt, June 2008.
(Additional references to be added later.)
Author's Address
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R. Atkinson
Extreme Networks
3585 Monroe Street
Santa Clara, CA
95051 USA
+1 (408)579-2800
rja@extremenetworks.com
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