On Thu, 27 Jun 2002, Maciej Soltysiak wrote:

> > > How to TCP keepalive packets look like? Also, isn't it possible that the
> > > third packet already carries data, in the general (read TCP protocol as
> > > it is written) case? You probably won't get that with the normal socket
> > > interface from userlevel, but does TCP forbid it? I don't think so.
> >
> > Correct. And besides when you receive data and have nothing to send
> > you'll ack with a zero-length packet.
> I agree.
>
> But that reminds me something.
> I had a problem once (not solved) with a novell server that used to send
> TCP packets with 2 bytes of data, then 52, then 2, then 52.
> It never sent packets filled to the MSS size as negotiated at the
> beginning.

Ummm - was this a 3.x or 4.x server (reason I ask is that I had a 3.x
server do this and I had to force the LIP option ON as well as fix an
intermediate router)? In 4.x this is fixed with a combo of the LIP and
some of the WAN link options (I forget which - have to go look).

> That caused the pop3 traffic to go terribly slow, and finally the server
> decided to close the connection due to timeout of not sending a mail
> message in time.

Yep - in my case it was actually the FTP session that did this...

> I tcpdumped the session, and did not see any, in my opinion, valid cause,
> like advertising a smaller tcp window.
>
> Also some (but not all) modem connection to the server had full 576 byte
> packets
>
> Any ideas on the cause?
>
> Regards,
> Maciej Soltysiak
>
>
>

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Matthew G. Marsh,  President
Paktronix Systems LLC
1506 North 59th Street
Omaha  NE  68104
Phone: (402) 932-7250 x101
Email: [EMAIL PROTECTED]
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