[AG-TECH] AG Problem - VIC freezing

Maat, Steve maats at wssu.edu
Tue Apr 29 09:36:06 CDT 2003

We have had similar problems. Every 5 minutes or so incoming streams would
freeze. Exiting/re-entering the venue or waiting a couple minutes and the
problem would clear - only to reoccur in another 5 minutes.  

Our network folks have been working on the problem and it appears to be a
multicast problem related to the code in one of our backbone routers
(Cisco). .

They have updated the code and prelimnary tests seem to have corrected the
problem, however we have not done extended testing yet. 

Another symptom of the problem (fixed by new IOS) is that occasionally,
after extended periods of operation the router would also stop passing tcp
traffic due to a buffer memory leak. We are co-coordinating a time to do
extended testing since the memory leak problem impacts more than just us.

Hope this helps...

Stephen Maat

-----Original Message-----
From: Mark Pellegrini [mailto:pellegrm at nesc.ac.uk]
Sent: Tuesday, April 29, 2003 5:35 AM
To: ag-tech at mcs.anl.gov
Subject: [AG-TECH] AG Problem - VIC freezing


I'm looking after the AG in the e-Science centre in Edinburgh.  We've
recently developed a problem that I can't figure out, especially as I'm
quite new to this.

After about 5 minutes of us being in a session all audio and video feeds
from other attending nodes freeze.  From talking to people over the MUD,
our audio and video is still functioning, as is that from the other

We've done some testing to try and isolate the problem.  I found that we
can restart other feeds in various ways, but only for about a minute and
a half, then the problem re-occurs.  If we exit and enter the venue
again, we can see and hear again for a shirt time; if we stop and
restart the VRM feeds at our end, things sort out briefly.  Killing the
VRM on the display node immediately restores audio, and this seems to
stay on.

If anyone has any advice on what I should be looking at, I'd be very

Mark Pellegrini 

Mark Pellegrini - pellegrm at nesc.ac.uk
Computing Support Officer - NeSC
Room 3.09  - eSI
South College St, Edinburgh
Tel: 0131 650 9812
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