Sam Stickland writes: > Iljitsch van Beijnum wrote: >> Yet all OSes have it enabled and there is no fallback to >> fragmentation in PMTUD: if your system doesn't get the ICMP >> messages, your session is dead in the water. >> > Windows Vista/2007 has black hole detection enabled by default. It's > not massively elegant, but it will keep sessions up (falls back to > 536 byte MTU).
> http://support.microsoft.com/kb/925280 Note that there's a new IETF specification (RFC 4821) for ("Packetization Layer") Path MTU discovery, which doesn't rely on ICMP messages to work. If what I wrote here http://kb.pert.geant2.net/PERTKB/PathMTU is correct, this has been implemented in recent (>= 2.6.17) Linux kernels. I don't know of any other OSes that have this yet - not that they'd tell me (but they could go and edit the page above, that's why it's a Wiki). -- Simon.
