Re: mtu 1499 works, mtu >= 1500 does not (1.3.91)

Pat Crean (pat@parrett.net)
Fri, 19 Apr 1996 10:19:06 +0000

We have noticed that several www sites (and, for a while, our own pop
server!) would hang when accessed through a ppp link. TCPDUMP
showed repeated acks from the server, but they apparently weren't
being sent on through the ppp session. Eventually everybody timed
out and the connection failed. Increasing the mtu from 552 to 1500
seems to have fixed the problem. I still don't know why it did this,
as I couldn't see any differences between the characteristics of
sites that worked and those that didn't. It scares me a bit to think
that it could crop up again with me still not having a clue :-)

For what it's worth, this is on an a.out system running 1.3.91 and
ppp-2.2.0f but has had the same problem since 1.3.59, and probably
before.

Pat

> Date: Fri, 19 Apr 1996 14:40:06 +0200 (MET DST)
> From: Bernd Wiebelt <bernardo@studi.mathematik.hu-berlin.de>
> To: linux-net@vger.rutgers.edu
> Cc: linux-kernel@vger.rutgers.edu
> Subject: mtu 1499 works, mtu >= 1500 does not (1.3.91)

>
> My machine here hangs on some www/ftp-servers (reproducable).
> Does nobody else encounter these hangs?
>
>
> --
> Bernd (bernardo@studi.mathematik.hu-berlin.de)
>
>
>