INTERNET-DRAFT               Link-Layer Option Extension      S. Goswami
Expires June 21, 2002                                           Self Inc
                                                            Dec 21, 2001


                   IPv6 Neighbor Discovery Link-Layer Option Extension
                <draft-goswami-ipv6-discovery-link-option-00.txt>


Status of this Memo

This document is an Internet-Draft and is in full conformance with all
provisions of Section 10 of RFC2026.

Internet-Drafts are working documents of the Internet Engineering Task
Force (IETF), its areas, and its working groups.  Note that other groups
may also distribute working documents as Internet-Drafts.

Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
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or to cite them other than as "work in progress."

The list of current Internet-Drafts can be accessed at
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The list of Internet-Draft Shadow Directories can be accessed at
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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 [RFC 2119].


Abstract

This document describes changes to the Source/Target Link-layer Address
option in IPv6 Neighbor Discovery Protocol [IPv6ND] to support addresses
of any liength.

1.  Overview and Rationale

The IPv6 Neighbor Disocvery Protocol uses Link-Layer addresses in option.
The option as it stands can only support link layer addresses of 6 + 8*n
octets, where n is natural number (i.e 0,1,2,3, ...). This precludes the
support for link layer addresses of arbitrary length that may need to
be supported in the future. One example of such an address is IEEE-EUI64
which is a 8 octet address.

2.  Additional Requirements for Link-Layer Options  for Neighbor Dicovery

This document adds two more option types to be used with Neighbor Discovery.
The

4.6.1.  Source/Target Any Length Link-layer Address

      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      |    Length     |    Link-Layer Address ...
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Fields:

      Type
                     11 for Source Any Length Link-layer Address
                     12 for Target Any Length Link-layer Address


      Length         The length of the option (including the type and
                     length fields) in units of 1/8 th  octets.  Forexample,
                     the length for IEEE 802 addresses is 1 [IPv6-
                     ETHER].

      Link-Layer Address
                     The variable length link-layer address.
                     The content and format of this field (including
                     byte and bit ordering) is expected to be specified
                     in specific documents that describe how IPv6
                     operates over different link layers.  For instance,
                     [IPv6-ETHER].

      Description
                     The Source Link-Layer Address option contains the
                     link-layer address of the sender of the packet.  It
                     is used in the Neighbor Solicitation, Router
                     Solicitation, and Router Advertisement packets.

                     The Target Link-Layer Address option contains the
                     link-layer address of the target.  It is used in
                     Neighbor Advertisement and Redirect packets.

                     These options MUST be silently ignored for other
                     Neighbor Discovery messages.

2.2 Router Solicitation Message

In addition to the options mentioned in [IPV6ND], the Source Any Length
Link-layer Address can be used.

2.3 Router Advertisement Message

In addition to the options mentioned in [IPV6ND], the Source Any Length
Link-layer Address can be used.

2.4 Neighbor Solicitation Message

In addition to the options mentioned in [IPV6ND], the Source Any Length
Link-layer Address can be used.

2.5  Neighbor Advertisement Message

In addition to the options mentioned in [IPV6ND], the Target Any Length
Link-layer Address can be used.

2.6 Redirect Message Format

In addition to the options mentioned in [IPV6ND], the Target Any Length
Link-layer Address can be used.


4.  Acknowledgments

The authors would like to thank Vince Laviano, Nidhi Bhaskar, and Steve
Deering and for their input and careful review.


5.  References

[IPV6ND] Narten, T, et. al., "Neighbor Discovery for IP Version 6
(IPv6)", RFC 2461, December 1998.

[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels," RFC 2119, March 1997.

[IANA-ALLOCATION] Internet Assigned Numbers Authority,
http://www.isi.edu/in-notes/iana/assignments/multicast-addresses.

[IEEE-EUI64] GUIDELINES FOR 64-BIT GLOBAL IDENTIFIER (EUI-64™)
REGISTRATION AUTHORITY, http://standards.ieee.org/regauth/oui/tutorials/EUI64.html




6.  Author's Address

     Dr. Subrata Goswami
     Self Inc.
     Newark, CA 94560
     sgoswami@umich.edu


This document expires June 21, 2002.