On 11/14/2012 09:50 AM, Brian E Carpenter wrote: >> Do we know of any use cases for IPV6_USE_MIN_MTU on TCP sockets? > > I think the use case is when there is a user option to use 1280 bytes > because of a path MTU limitation due to a tunnel, *and* PMTUD and/or > fragmentation fails. (Read draft-taylor-v6ops-fragdrop and be scared.)
Will read the draft later. Thanks for the pointer. > So using it to trigger fragmentation is pointless; to me the only thing > that makes sense is if it reduces the MSS accordingly. I've seen > that fail in the wild, when running 6to4. I totally agree. Reducing the MSS is the only sane thing this socket option can do on a TCP socket. >> Will >> DNS server software vendors would use it as fallback to UDP? > > Huh? They are in bad trouble with UDP if running DNSSEC and fragmentation > doesn't work. So they could try TCP after some retries, perhaps already with reduced MSS in place. -- Hannes Sowa <[email protected]> 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 [email protected] Administrative Requests: https://www.ietf.org/mailman/listinfo/ipv6 --------------------------------------------------------------------
