Date: Tue, 8 Dec 2009 11:55:44 +0200 From: Andriy Syrovenko <andriys@gmail.com> To: Bruce Simpson <bms@incunabulum.net> Cc: freebsd-net@freebsd.org, flo@smeets.im Subject: Re: kern/138666: [multicast] [panic] not working multicast through igmpproxy Message-ID: <3e2b8dd90912080155s544a7a50j17882b35f1343750@mail.gmail.com> In-Reply-To: <4B1E1EF0.8040503@incunabulum.net> References: <200912071020.nB7AK77I023054@freefall.freebsd.org> <4B1CDEE5.6080507@incunabulum.net> <3e2b8dd90912070305t6ffc08a6gf7acd8890d028854@mail.gmail.com> <4B1D07C3.6090005@incunabulum.net> <3e2b8dd90912080114x31d962acqf2c8a360e7b5a83d@mail.gmail.com> <4B1E1EF0.8040503@incunabulum.net>
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2009/12/8 Bruce Simpson <bms@incunabulum.net>: > Andriy Syrovenko wrote: >> >> I have switched to 8-STABLE. Kernel does not seem to crash anymore, >> however IGMP still does not work. tcpdump complains that outgoing IGMP >> report and leave packets have incorrect checksum- it is always 0. >> Though I'm not sure weather it is IGMP checksum or IP checksum that is >> incorrect. >> > > This just sounds like a fairly normal artefact of tcpdump/bpf with checks= um > offload, as I get the exactly same thing on my desktop w/ re(4). > > You need to confirm the checksums at the wire to be sure, or disable > rxcsum/txcsum: > =A0 # ifconfig re0 -txcsum -rxcsum I've checked w/ tcpdump on my MacBook connected to the same LAN segment the upstream interface of my router is connected to. The packets on the wire have bad checksums. And yes, I have re(4) interfaces as well. I'll try turning off checksum offloading today evening, as soon as I get to my router. > Nothing has changed in the behaviour of the code which computes IGMP > checksums; it does not depend on the outer IP header, and isn't touched b= y > IP checksum offload, unless your network card (or its driver) is doing > something it shouldn't be doing. I have looked through the tcpdump source code, and am now fairly confident that it is IP (not IGMP) checksum that is broken. > Perhaps Florian can shed some light on your IGMP issue? igmpproxy only > understands IGMPv2, afaik. Yep, it is igmp v2 only indeed.
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