Date: Tue, 26 Apr 2005 12:06:14 +0200 From: Andre Oppermann <oppermann@networx.ch> To: David Malone <dwmalone@maths.tcd.ie> Cc: freebsd-current@freebsd.org Subject: Re: DF (Don't frag) issues Message-ID: <426E1296.DF6264EF@networx.ch> References: <200504261055.aa95182@salmon.maths.tcd.ie>
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David Malone wrote: > > > > I wonder if we could look into the quoted IP header and extract the > > > length of the IP packet that caused the needs-frag ICMP. That would > > > stop us getting in knots when there are a few packets in flight and > > > would give us a good idea about where we need to step down from. > > > This is a really clever idea indeed. But it only works if part of > > the original packet is attached. Broken implementations are likely > > to omit that. But I'll implement your suggestion as well and post > > a new patch later this evening. > > In the case of TCP PMTU we should be OK because we to get as far > as the TCP code I think we'll always have enough quoted packet? > Of course, in the more general case we can't always do this, but > it should help in a lot of cases. There is no general case anymore as we must ignore those packets. Otherwise we have open up the hole again. Which means we always have the IP header. On the other hand it means that it is very likely, if not certain, that we get a suggested MTU value. -- Andre
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