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IPv6 questions at the document ready party...



This note is primarily for the IPsec list, but I'm sending it to IPng as
well.

Two questions/issues that came up during the part of the document reading
party in Washington were:

	1.) The fragment header in reassembled packets and its impact on AH?

People were concerned (I think) that after packet reassembly, an IPv6
datagram _might_ be delivered to AH looking like:

	 IP + <leftover fragment hdr> + AH + <payload>

An IPv6 implementation MUST NOT deliver such a datagram to a
higher-level-protocol, including other IPv6 option types.  Once reassembly is
performed, the fragment header is stripped out.  Lemme quote the relevant
section from RFC 1883...

>    At the destination, fragment packets are reassembled into their
>    original, unfragmented form, as illustrated:
> 
>    reassembled original packet:
> 
>    +------------------+----------------------//------------------------+
>    |  Unfragmentable  |                 Fragmentable                   |
>    |       Part       |                     Part                       |
>    +------------------+----------------------//------------------------+

Note the consipicuous absence of a fragment header.  :)


	2.) What protocol number for inner-payload == IPv6?

The answer is 41 (IPv6-in-IP??), not 4(IP-in-IP), but 41.

Hope this helps.
--
Daniel L. McDonald  -  Solaris Internet Engineering  ||  MY OPINIONS ARE NOT
Mail: danmcd@eng.sun.com, danmcd@kebe.com <*>        ||  NOT NECESSARILY SUN'S!
Phone: (650) 786-6815            |"rising falling at force ten
WWW: http://www.kebe.com/~danmcd | we twist the world and ride the wind" - Rush