Date: Wed, 2 Oct 1996 20:06:32 +1000 (EST) From: Rowan Crowe <rowan@ozramp.net.au> To: Peter Wemm <peter@spinner.DIALix.COM> Cc: David Greenman <dg@root.com>, bugs@FreeBSD.ORG Subject: Re: Possible low level TCP bug Message-ID: <Pine.LNX.3.91.961002200143.3654C-100000@ozramp> In-Reply-To: <199610020929.RAA22086@spinner.DIALix.COM>
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On Wed, 2 Oct 1996, Peter Wemm wrote: > > > >The behaviour is this: seemingly small amounts of complete data (ie: a > > > >line on IRC) are split into two packets, and are sent about a second > > > >apart. The trace from my current router (not a FreeBSD box) shows this > > > >behaviour. Note the first packet has the PSH attribute. > > > > > > What kind of ethernet card are you using? ...or is this with PPP or SLIP > ? > > Don't laugh: I use 3c501 ethernet cards. The capture I sent to you was > > carried over the ethernet from my FreeBSD box. However, I doubt that's > > the problem, as I've observed inbound data (via serial/PPP) with this > > same quirk. > > Hmm, I wonder if we're running into the (pre-pathmtu) 576 default tcp mss > somewhere with the extra tcp headers? Doubtful, the data in the packet was about 100 bytes, and the IP length is only 140 bytes. Other packets with 500+ bytes of data go through fine, most of the time. This quirk is only noticed *occasionally*. :-) I will see if I can reproduce this with some other software, so far it's been IRCII (client) and whatever aussie.oz.org uses (IRCD?). Perhaps there's a shared library or common routine which is causing this problem. Cheers.
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