Subject: Issue 19: AD review of draft-ietf-ipv6-node-requirements-05.txt

From: [email-masked]
Date: Wed, 24 Sep 2003 14:17:00 +0300

> >    Nodes MUST always be able to receive fragment headers. However, if it
> >    does not implement path MTU discovery it may not need to send
> >    fragment headers.  However, nodes that do not implement transmission
> >    of fragment headers need to impose a limitation to the payload size
> >    of layer 4 protocols.
>      
> This would seem inconsistent with the following wording in RFC 2460:
> 
>     In response to an IPv6 packet that is sent to an IPv4 destination
>     (i.e., a packet that undergoes translation from IPv6 to IPv4), the
>     originating IPv6 node may receive an ICMP Packet Too Big message
>     reporting a Next-Hop MTU less than 1280.  In that case, the IPv6 node
>     is not required to reduce the size of subsequent packets to less than
>     1280, but must include a Fragment header in those packets so that the
>     IPv6-to-IPv4 translating router can obtain a suitable Identification
>     value to use in resulting IPv4 fragments.  Note that this means the
>     payload may have to be reduced to 1232 octets (1280 minus 40 for the
>     IPv6 header and 8 for the Fragment header), and smaller still if
>     additional extension headers are used.

So, this should be changed to:

	Nodes MUST always be able to send and receive fragment headers. (rest of
	the text deleted)

John

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