On 11/13/2012 12:27 AM, Mark Andrews wrote: > In message <50a111fb.2060...@bfk.de>, Hannes Frederic Sowa writes: >> On 11/07/2012 02:30 AM, Mark Andrews wrote: >>> Should setting IPV6_USE_MIN_MTU to one (1) result in fragmented TCP packets? >>> Should setting IPV6_DONTFRAG to one (1) work on TCP sockets? >> >> As I have not read otherwise I would treat IPV6_USE_MIN_MTU as >> transport-agnostic. > > The problem is that there are at least 2 OS's with TCP layers that > do not use IPV6_USE_MIN_MTU when calculating the TCP segment size to > send. I would have thought that this would have been obvious to do. > > Do we need update RFC3542 to say that IPV6_USE_MIN_MTU is to be used > when calculating the TCP segment size?
Do we know of any use cases for IPV6_USE_MIN_MTU on TCP sockets? Will DNS server software vendors would use it as fallback to UDP? >> The usage of IPV6_DONTFRAG is only specified on UDP and raw sockets (see >> RFC3542 11.2). > > Which is short sighted. There is no reason not to apply it to all > transports as all transports have to handle PTB and this is just > a locally generated PTB. > > And while we are talking about RFC3542 how to we get POSIX updated to > include the advanced half of the API as it is a pain in the butt for > application developers. Seems this is already the case. I looked at some usees of IPV6_USE_MIN_MTU and i.e. bind is already working around some strange setsockopt interactions with other options on FreeBSD (bind specifies IPV6_USE_MIN_MTU as a per packet control message there). -- Hannes Sowa <hs...@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 --------------------------------------------------------------------
