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On Jan 5, 2012, at 2:45 AM, "Florian Weimer" <fwei...@bfk.de> wrote: > * Fernando Gont: > >> In that case, you're not required to split your packets into fragments >> smaller or equal to 1280 bytes, but *are* required to react by including >> a Fragment Header in subsequent packets. > > And the only way to achieve that reliably in certain existing > deployments appears to be to send a fragment header unconditionally. > (And with increasing IPv6 adoption, this will be only option for every > large DNS operator---right now, PMTUD in the IPv6 stack appears to work > because the number of clients is small compared to the size of the > destination cache in the servers.) > > Steinar wrote that atomic fragments break FreeBSD 7.4 (and there might > be others, of course). Not sending them breaks important transition > technology. > >>> Without the API change in draft-andrews-6man-force-fragmentation, it is >>> flat out impossible to server IPv6 traffic in a stateless fashion. The >>> stack is required to keep a per-destination cache which records the >>> necessity of a fragment extension header, even if the application never >>> sends any packets larger than 1280 bytes. >> >> The stack is required to have a Destination Cache, anyway. > > Could you elaborate on that? For some operators, the ability to serve > stateless protocols statelessly over IPv6 is quite important. I'm not > aware of any fundamental requirement for per-destination bookkeeping in > IPv6 nodes. > >>>> Sorry, I cannot see why some packets would require going through a >>>> translator, while others wouldn't. >>> >>> The joy of packet switching. 8-) >> >> If a packet is actually destined to the IPv4 world (and hence needs to >> go through a translator), it will need to cross one translator, or >> another... but *some* translator. > > Couldn't it be translated back to IPv6? Then there could be an > IPv6-only path between sender and recipient. I'm deploying it. It's hard to find. > > -- > Florian Weimer <fwei...@bfk.de> > BFK edv-consulting GmbH http://www.bfk.de/ > Kriegsstraße 100 tel: +49-721-96201-1 > D-76133 Karlsruhe fax: +49-721-96201-99 > -------------------------------------------------------------------- > IETF IPv6 working group mailing list > ipv6@ietf.org > Administrative Requests: https://www.ietf.org/mailman/listinfo/ipv6 > -------------------------------------------------------------------- -------------------------------------------------------------------- IETF IPv6 working group mailing list ipv6@ietf.org Administrative Requests: https://www.ietf.org/mailman/listinfo/ipv6 --------------------------------------------------------------------
