In your letter dated Mon, 18 Jul 2011 22:25:30 +1000 you wrote: >I'm puzzled by something in RFC1981, which discusses PMTUD and IPv6. > >It contains these two paragraphs towards the end of Section 4: > > A node MUST NOT reduce its estimate of the Path MTU below the IPv6 > minimum link MTU. > > Note: A node may receive a Packet Too Big message reporting a > next-hop MTU that is less than the IPv6 minimum link MTU. In that > case, the node is not required to reduce the size of subsequent > packets sent on the path to less than the IPv6 minimun link MTU, > but rather must include a Fragment header in those packets [IPv6- > SPEC]. > >What does that mean - "insert a Fragment header"? And it may not be >*required* to reduce the size of subsequent packets, but does that mean >it *can* if it wants to? And isn't inserting a whole new header a bit >counterproductive if someone is telling your your packets are too big >already? All in all I have this strong feeling I'm missing something >obvious. Any clues gratefully received.
I think that there was a tunneling protocol that would need the fragment ID in the fragment header to do fragmentation on the lower layer or something like that. It never made much sense to me. -------------------------------------------------------------------- IETF IPv6 working group mailing list ipv6@ietf.org Administrative Requests: https://www.ietf.org/mailman/listinfo/ipv6 --------------------------------------------------------------------
