Date: Fri, 1 Feb 2002 18:03:02 +0200 From: Alexey Luckyanchikov <alexl@alkar.net> To: "Louis A. Mamakos" <louie@TransSys.COM> Cc: freebsd-stable@FreeBSD.ORG, freebsd-net@FreeBSD.ORG Subject: Re: Weird path MTU autodiscovery problem in 4.5-RELEASE Message-ID: <20020201160302.GD15303@alkar.net> In-Reply-To: <200202011550.g11Forp17319@whizzo.transsys.com> References: <20020201125326.GA3036@alkar.net> <3C5AB477.3000304@tenebras.com> <200202011550.g11Forp17319@whizzo.transsys.com>
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On Fri, 01 Feb 2002, Louis A. Mamakos wrote: LAM> Is the server filtering out ICMP traffic with ipfw or something? Server have not any filters. ipfw support is compiled in, but first rule is 'allow ip from any to any' and dump which you can see below was made on server. LAM> > Alexey Luckyanchikov wrote: LAM> > LAM> > LAM> > > 14:06:48.477578 server.7 > client.1371: . 1437:2897(1460) ack 10001 win 65535 (DF) (ttl 64, id 25428, len 1500) LAM> > > ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ LAM> > > Server send packet with size 1500 bytes LAM> > > LAM> > > 14:06:48.682558 router > server: icmp: client unreachable - need to frag (mtu 1476) for server.7 > client.1371: [|tcp] (DF) (ttl 61, id 25428, len 1500) (ttl 253, id 2491, len 56) LAM> > > ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ LAM> > > Router say to server that he must to decrease packet size LAM> > > LAM> > > 14:07:04.477857 server.7 > client.1371: . 1437:2897(1460) ack 10001 win 65535 (DF) (ttl 64, id 52781, len 1500) LAM> > > ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ LAM> > > But server ignore this information and still send 1500 bytes packets LAM> > LAM> > LAM> > What's the result of 'sysctl net.inet.tcp.path_mtu_discovery' ?? Not that LAM> > I can imagine, at the moment, what would set it to 0.... -- Sincerely, e-mail: alexl@alkar.net Alexey Luckyanchikov To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-net" in the body of the message
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