In article <Pine.LNX.4.44.0208230917540.23138-100000@netcore.fi> you wrote: > Umm.. PMTUD is for everything, AFAICS. It's mostly seen with UDP though > (TCP less so). nope. Path MTU Discovery is done by the Kernel for TCP only. For UDP applications can do it. In case of UDP it makes only sence for streaming applications. ICMP does not do PMTU. PMTU discovery cant work very well with ICMP since IP-Stacks are generally very picky about answering to ICMP Messages with errors MEssages (like Fragmentation needed). For UDP the kernel will pass FragNeeded messages back to the application as an hard error, if PMTU Discovery is activated. For TCP the kernel will adopt the freshly discovered packet size in the routing table cache as the maximum segment size. You can see them if you do "route -C". BTW: if you have a masquerading gateway, which is doing MSS clamping, you will not see a change in the MSS on the host site. Same is true for a router-less connection. Greetings Bernd - : send the line "unsubscribe linux-net" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
