Date: Thu, 21 Feb 2002 11:25:51 -0800 From: Alfred Perlstein <bright@mu.org> To: Lars Eggert <larse@ISI.EDU> Cc: net@freebsd.org Subject: Re: incorrect checksums with xl? Message-ID: <20020221192551.GG12136@elvis.mu.org> In-Reply-To: <3C7547E0.8050805@isi.edu> References: <3C7547E0.8050805@isi.edu>
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* Lars Eggert <larse@ISI.EDU> [020221 11:18] wrote: > Hi, > > I'm looking at a packet trace taken of an xl card under 4.5, and I see > bad IP and TCP/UDP checksums. The release notes state that checksumming > maybe offloaded to the NIC now, but I'd still expect them to be correct > in a packet trace! > > More specifically, the IP checksum is always zero, while the TCP and UDP > checksums are non-zero but bad. However, netstat shows no packets > arriving with bad checksums, so I assume that they get mangled somewhere > in the kernel after inbound processing. (And the machine works fine on a > network; I found this by accident.) > > Any clues? I'm not 100% on this, but bpf may be queueing the packet without doing a deep copy of it? Another thing may be that the card performs the checksum but uses the checksum area as a scratch area? -- -Alfred Perlstein [alfred@freebsd.org] 'Instead of asking why a piece of software is using "1970s technology," start asking why software is ignoring 30 years of accumulated wisdom.' Tax deductible donations for FreeBSD: http://www.freebsdfoundation.org/ To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-net" in the body of the message
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