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From: Nikos Vassiliadis <nvass@teledomenet.gr>
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Date: Thu, 31 Jul 2008 10:27:37 +0300
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Cc: Giorgos Keramidas <keramida@ceid.upatras.gr>, perryh@pluto.rain.com,
	Derek Ragona <derek@computinginnovations.com>
Subject: Re: setting the other end's TCP segment size
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On Thursday 31 July 2008 01:21:25 Giorgos Keramidas wrote:
> On Wed, 30 Jul 2008 16:20:06 -0500, Derek Ragona 
<derek@computinginnovations.com> wrote:
> > At 11:04 PM 7/29/2008, perryh@pluto.rain.com wrote:
> >> > [TCP] splits traffic to 'segments' using its own logic ...
> >>
> >> Is there a simple way for a FreeBSD system to cause its peer to use a
> >> transmit segment size of, say, 640 bytes -- so that the peer will
> >> never try to send a packet larger than that?
> >>
> >> I'm trying to get around a network packet-size problem.  In case it
> >> matters, the other end is SunOS 4.1.1 on a sun3, and I've been unable
> >> to find a way to limit its packet size directly.
> >
> > Just as an FYI, you might want to do:
> > man setsockopt
> > ro
> > man getsockopt
> >
> > Each tcp conversation can have it's own size set along with a bunch of
> > other params.
>
> Good point.  The TCP_MAXSEG can reduce the maximum segment size for a
> single TCP connection to something smaller than the interface MTU :)

Just adding that MTU can be set per destination with the help of
route(8) and the -mtu modifier.