In message <1352259190.4281.104.camel@karl>, Karl Auer writes: > On Wed, 2012-11-07 at 12:30 +1100, 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? > > [...] > > Both options were set on the socket with the resulting packet trace. > > Speaking from a position of ignorance here, but my understanding is that > if you use the first, the second is ignored, which is what seems to be > happening in that trace. > > I also believe that the second does not apply to TCP. > > I'd expect that if you use the first then PMTUD should be disabled and > the stack will fragment larger packets normally and send atomic > fragments if the whole thing (plus fragment header) fits in a single > fragment. If the implementation doesn't believe in atomic fragments then > it will fragment only packets too large to fit in 1280 bytes and will > send smaller ones without a fragment header.
I'd expect the TCP layer to look at the IP layer MTU and adjust its segment size to match. > That said, I reiterate my ignorance. > > Regards, K. > > -- > ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ > Karl Auer ([email protected]) > http://www.biplane.com.au/kauer > http://www.biplane.com.au/blog > > GPG fingerprint: AE1D 4868 6420 AD9A A698 5251 1699 7B78 4EEE 6017 > Old fingerprint: DA41 51B1 1481 16E1 F7E2 B2E9 3007 14ED 5736 F687 -- Mark Andrews, ISC 1 Seymour St., Dundas Valley, NSW 2117, Australia PHONE: +61 2 9871 4742 INTERNET: [email protected] -------------------------------------------------------------------- IETF IPv6 working group mailing list [email protected] Administrative Requests: https://www.ietf.org/mailman/listinfo/ipv6 --------------------------------------------------------------------
