Date: Wed, 24 Oct 2012 06:48:37 -0700 From: Adrian Chadd <adrian@freebsd.org> To: Harald Schmalzbauer <h.schmalzbauer@omnilan.de> Cc: FreeBSD Stable <freebsd-stable@freebsd.org> Subject: Re: every 2nd echo-request malformed when ping -s >4067 Message-ID: <CAJ-Vmompr2EhK=ddDnQ6EZxtqBckryCzPyDAnWUzBvKRbae2fg@mail.gmail.com> In-Reply-To: <5087DFA1.7090001@omnilan.de> References: <5087DFA1.7090001@omnilan.de>
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On 24 October 2012 05:31, Harald Schmalzbauer <h.schmalzbauer@omnilan.de> wrote: > Hello, > > while checking new mtu9k-setup, I discovered that ping has some odd > behaviour. > If I use payloadsize > 4067, every 2nd icmp-echo-request seems to be > malformed: Is this on -HEAD? > ping -s 4068 -D 10.5.49.65 > > 1st: 12:21:09.048447 IP 10.5.49.126 > 10.5.49.65: ICMP echo request, id > 46597, seq 0, length 4076 > 0x0000: 4500 1000 0f2d 4000 4001 a507 0a05 317e > > 2nd: 12:21:10.052891 IP 10.5.49.126 > 10.5.49.65: icmp > 0x0000: 4500 1000 0f2d 0040 4001 e4c7 0a05 317e > > 3rd: 12:21:11.062900 IP 10.5.49.126 > 10.5.49.65: ICMP echo request, id > 46597, seq 2, length 4076 > 0x0000: 4500 1000 0f2d 4000 4001 a507 0a05 317e > > 4th: 12:21:12.072915 IP 10.5.49.126 > 10.5.49.65: icmp > 0x0000: 4500 1000 0f2d 0040 4001 e4c7 0a05 317e > > 5th: 12:21:13.082900 IP 10.5.49.126 > 10.5.49.65: ICMP echo request, id > 46597, seq 4, length 4076 > 0x0000: 4500 1000 0f2d 4000 4001 a507 0a05 317e > > When payload is 4076, outgoing _every_ outgoing request begins with > 4500 xxxx xxxx 4000 4001, > while above we see every second request starting with > 4500 xxxx xxxx 0040 4001. > Does anybody know header composing off pat? Haven't seen these bits for > quiet some time... Glebius was recently in the networking stack in -HEAD, fiddling with how IP headers are treated. Maybe this is some corner case fallout from that? adrian
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