Problems with TCP on 1.3.9[34]

Ulrich Klein (ulik@hprc.tandem.com)
Fri, 26 Apr 1996 00:21:33 +0200 (MST)


Hi,

I have a problem with kernel 1.3.9[34] and ftp.
I connect from my home Linux machine using isdn4linux/ipppd to an Ascend
pipeline400 on our office net. Everything works fine (no routing problem...)
When I try to ftp a file from home to the office this will succeed, but ..
if during the ftp transfer I do an rlogin to the machine I'm transferring to
the ftp-data connection immediately stops. I can reliably reproduce this
with a variety of machines (Solaris2.4, IRIX5.2, Linux1.3.71, UnixWare2.03
and Tandem's NS-UX) on the other end, so I'm quite sure it's a problem
on my 1.3.94 side. It doesn't matter from which side I start the transfer,
ftp-put on home machine or ftp-get from office always the same result.
Transferring from the office to the 1.3.94 machine does work without a problem.

I'm not sure if this is a TCP/IP problem or an isdn4linux problem, so my
question is: has anybody seen this behaviour with other TCP connections
that do not operate at ethernet speed?

I snooped (Solaris' tcpdump) on of those failed ftps. If anybody is interested
I'll send it. To me the trace does not look unusual, except for the end when
the Sun stopped acking packets for some reason. (No, I don't think its a
problem with Solaris, see above)

Oops, right now one of my rlogin sessions is in that state. netstat says:
tcp 0 49 zorro.hprc.tandem:1021 suse.hprc.tandem:login ESTABLISHED ulik

and for each char I type the Send-Q grows

Hoping that someone can help
Uli

--
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Ulrich Klein
Tandem Inc. HPRC                  Phone: +49-6172-7369-52
Max-Planck-Str. 36                FAX  : +49-6172-74655
D-61381 Friedrichsdorf            Email: ulik@suse.hprc.tandem.com
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