Date: Fri, 1 Feb 2002 18:13:19 +0200 From: Alexey Luckyanchikov <alexl@alkar.net> To: Michael Sierchio <kudzu@tenebras.com> Cc: freebsd-stable@freebsd.org, freebsd-net@freebsd.org Subject: Re: Weird path MTU autodiscovery problem in 4.5-RELEASE Message-ID: <20020201161319.GA948@alkar.net> In-Reply-To: <3C5AB477.3000304@tenebras.com> References: <20020201125326.GA3036@alkar.net> <3C5AB477.3000304@tenebras.com>
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Hello, On Fri, 01 Feb 2002, Michael Sierchio wrote: MS> Alexey Luckyanchikov wrote: MS> MS> MS> >14:06:48.477578 server.7 > client.1371: . 1437:2897(1460) ack 10001 win MS> >65535 (DF) (ttl 64, id 25428, len 1500) MS> >^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ MS> >Server send packet with size 1500 bytes MS> > MS> >14:06:48.682558 router > server: icmp: client unreachable - need to frag MS> >(mtu 1476) for server.7 > client.1371: [|tcp] (DF) (ttl 61, id 25428, len MS> >1500) (ttl 253, id 2491, len 56) MS> >^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ MS> >Router say to server that he must to decrease packet size MS> > MS> >14:07:04.477857 server.7 > client.1371: . 1437:2897(1460) ack 10001 win MS> >65535 (DF) (ttl 64, id 52781, len 1500) MS> >^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ MS> >But server ignore this information and still send 1500 bytes packets MS> MS> MS> What's the result of 'sysctl net.inet.tcp.path_mtu_discovery' ?? Not that 1 MoS> I can imagine, at the moment, what would set it to 0.... Yes, set net.inet.tcp.path_mtu_discovery to 0 or set MTU on server to 1476 help. But it is only workaround. -- 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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