Path: utzoo!utgpu!news-server.csri.toronto.edu!mailrus!tut.cis.ohio-state.edu!oscsunb!kannan
From: kannan@osc.edu (Kannan Varadhan)
Newsgroups: comp.dcom.sys.cisco
Subject: Re: help needed debugging DDS 56kb prob
Message-ID: <890@manhandler.osc.edu>
Date: 10 Sep 90 11:53:03 GMT
References: <25924@boulder.Colorado.EDU> <3970@ursa-major.SPDCC.COM>
Organization: Ohio Supercomputer Center & OARNet, Columbus, OH
Lines: 38

Thus spake dyer@ursa-major.spdcc.COM (Steve Dyer)
>In any event, the "fix" appears to have been a coincidence.  Having moved the
>equipment to its permanent resting place, the carrier transitions and
>interface resets (after a stable, peaceful weekend) have returned with a
>vengeance, even with the parameter set to 56kb.  I think I'm in the
>nether world of flaky cables/modems, and will pursue it on that level.

We have a 9.6kB line on which we see such a similar occurence.

We hypothesized that what's happenning is that the line is saturating
with data, and then some, causing even the router's memory to fill up.
Thereafter, once the router's miss 3 hdlc keepalive patterns, they reset
the line etc. etc. etc.

The salesperson's suggestion was that we turn off the keepalives on that
circuit, so that such interface resets did not happen.  You might try
that.

We did not try that, because we were actually working on a different
problem, and thought this was the cause of it, when it wasn't.  Having
fixed the other problem, we curled into our own cute li'll cubby holes,
and went back to hibernation yet again :-).

Check the throughput and errors on the line, and see if they occur when
there is a large volume of data flowing through them.   You could
recreate this by, say, flood-pinging the line with ultra-large packets,
and watching the status of the line.  Track traffic patterns for a
while, and see if there is any co-relation between these and interface
resets.


Best I can think of in a pinch...hope these help,

Kannan
-- 
Kannan Varadhan, Internet Engineer, OARNet
Ohio Supercomputer Center, Columbus, OH 43212	+1 (614) 292-4137
email:	kannan@oar.net	|  osu-cis!malgudi.oar.net!kannan