[305] in linux-net channel archive
PPP problems with 1.2.8
daemon@ATHENA.MIT.EDU (Al Longyear)
Wed May 10 16:25:15 1995
Date: Wed, 10 May 1995 11:21:49 -0700
To: linux-ppp@vger.rutgers.edu, linux-net@vger.rutgers.edu
From: longyear@netcom.com (Al Longyear)
Cc: callahan@maths.ox.ac.uk (Michael Callahan)
In the 1.2.8 kernel, a patch was made to the ppp.c driver.
It involved several main areas. The first of which was a problem which
occurred when the network connection was abnormally terminated. This caused
a problem between the tty 'face' and the network 'face' of the ppp driver.
The second problem dealt with the proper calling of the vj header
compression procedure slhc_toss when a frame was received in error. This was
erroneously forgotten in earlier versions and may have caused problems with
the reception of vj header compressed data.
The last problem was the addition of the logic needed to compress the vj
header connection id. The vj header connection id compression is something
which is negotiated between the two ends of the PPP link. Previous versions
would announce that they would accept and wanted to be able to send a
compressed connection id. However, Linux never sent one. This was changed in
1.2.8.
The change seems to have uncovered a flaw in the pppd daemon code. While it
will work properly with systems which compress the connection id, it does
not work properly with those systems which don't.
The most notable of these is the Annex Terminal server by Xylogics which is
used by many service providers. The Trumpet PPP stack used on Microsoft
Windows 3.x will also be similarly effected.
There is nothing wrong with the terminal server so please don't pester
Xylogics. The problem is in the daemon code used for Linux PPP.
For a 'work around' solution, until I can properly fix the daemon, please
use the option -vjccomp. This will tell the daemon that it is not to
compress the connection id. Please add this option to any other option
sequence which you are using with pppd if you have problems with the ppp
code in 1.2.8.
The most profound problem will be the speed in sending data will drop
dramatically. It should not effect your ability to receive data.
I hope to have a solution shortly. However, for the time being, please
include the option to disable the feature. If you don't know wether or not
you need to include the option, then ask the simple question "did the speed
drop dramatically between 1.2.7 and 1.2.8?" If so, then use the option.
I do not wish to remove the 'patch'. It is proper that the driver do this
operation. The solution is to fix the bug in the daemon. This bug is in all
of the ports of the pppd process; not just Linux.
Thank you.
--
Al Longyear longyear@netcom.com longyear@sii.com
The public pgp 2.6 key is available by fingering longyear@netcom.com.
