Date: Sun, 24 Apr 2005 18:21:30 +0200 From: Andre Oppermann <andre@freebsd.org> To: David Malone <dwmalone@maths.tcd.ie> Cc: freebsd-current@freebsd.org Subject: Re: DF (Don't frag) issues Message-ID: <426BC78A.3E56D99B@freebsd.org> References: <426426AE.2060406@uq.edu.au> <20050420084413.GA27304@walton.maths.tcd.ie> <42663EA1.3020409@uq.edu.au> <426A3F49.6090203@uq.edu.au> <20050424150211.GA87520@walton.maths.tcd.ie>
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David Malone wrote: > > On Sat, Apr 23, 2005 at 10:27:53PM +1000, Matthew Sullivan wrote: > > Ok well thanks to Andrew @ Supernews and a lot of debugging it appears > > there is a bug.... > > > > sys/netinet/ip_icmp.c: line 440 > > if (!mtu) > > mtu = ip_next_mtu(mtu, 1); > > Problem is ip_next_mtu will always return 0 when called with (0, 1) ... > > I think this might be a bug, but Andre would know better. Andre - > it looks to me as if the first argument to ip_next_mtu here should > be the current MTU for the path, but it is being set to the mtu > from the ICMP message, which (in this case) is zero. This is a bug indeed. Let me think how to fix this most efficiently... > (This is in the code that has just been moved to tcp_ctlinput.) > > > Apparently the gateway should be suggesting a MTU value for use.... the > > gateway is also FreeBSD 5.3 so something needs fixing .. :-/ > > Are you using ip fast forwarding on the gateway? It calculates the > size that is put into the ICMP message in a slightly different way > to the other forwrd path. The quoted code above is used only for incoming ICMP packets. It does not generate them? What is the problem being observed exactly? -- Andre
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