[2172] in linux-net channel archive
Re: LCP echo problems (again)
daemon@ATHENA.MIT.EDU (Al Longyear)
Wed Mar 20 10:20:29 1996
To: linuxsys@ssg.com
Date: Wed, 20 Mar 1996 07:07:52 -0800 (PST)
From: "Al Longyear" <longyear@netcom.com>
Cc: linux-net@vger.rutgers.edu, Paul.Mackerras@cs.anu.edu.au (Paul Mackerras)
In-Reply-To: <199603201337.AA07632@ssg.com> from "linuxsys@ssg.com" at Mar 20, 96 01:37:54 pm
linuxsys@ssg.com wrote:
> I wrote:
> > The most common problem is that they totally freq out when they see a unknown
> > frame. They will usually follow the RFC in that they will send a protocol
> > reject, but they fail to understand that the CCP frame is an independent
> > protocol and they try to take down the link when they see the CCP frame.
> A follow-up question: is there a quick and easy way to verify that a
> host is not handling CCP frames correctly?
Technically, no. There is no way to know from just your side. You
would need to look at the log files (if there are any) on the peer
system.
Empirically, yes. That comes with experience. I can only say that it
is like an 'expert system'. You learn to pick up on the signatures of
the problems.
This one is fairly obvious.
Linux pppd version 2.2 sends an empty CCP frame if you don't have any
compressors defined. This is what was argued about for a few weeks on
the IETF working group mail list. It means "I know CCP. I just don't
want to do it." The peer system sends a protocol reject if they don't
understand the protocol. Shortly thereafter, the line terminates. This
happens even sometimes before the IPCP sequence completes.
Sometimes, the peer will attempt to restart the IPCP sequence. In this
case you will see that the IP layer will go down and then back up. You
can tell this by seeing the list of the two IP addresses in the system
log being printed twice (and not like yours where you have multiple
entries in your syslog.conf file pointing to the same file.)
Others will simply just terminate.
However, the 'signature' seems to be that they all do this just after
the Linux pppd process sends the CCP frame.
It is usually accompanied by the person telling me "but it worked with
2.1.2!"
I did argue the point with Paul Mackerras in that the pppd process
should work like the 2.1 version if you don't have a compressor
defined in that it should not have sent the empty CCP frame.
I was overruled.
--
Al Longyear longyear@netcom.com longyear@sii.com
Finger longyear@netcom.com for PGP public key.
