[AG-TECH] I broke something on my video. Need help!

John I. Quebedeaux, Jr johnq at lsu.edu
Wed Jan 12 13:30:41 CST 2011


One little bit missing to help: are you using unicast bridging to connect
your video/audio traffic? (if so, which bridge?) or are you using multicast?
If it's multicast, then something about your multicast networking 'broke'
between yourself and the other sites... If it's unicast - perhaps you
connected to a different bridge than what the other sites are using and
multicast between the bridges is 'broke'.

I.e. There is a distinct difference in how the video and audio traffic is
'met' by the clients VIC and RAT if you're unicast or multicast where with
unicast you must 'connect' to a bridge that can relay the traffic to/from
everyone else on a multicast group. Multicast is nice in that the
video/audio traffic doesn't rely on a single computer to relay that traffic,
it's done by the routers directly to the receivers looking to connect to the
source of that traffic. A combination of unicast and multicast can be used
but things can breakdown if different bridges being utilized by the clients
involved cannot see each other.

Understanding a bit about unicast vs multicast can help with troubleshooting
what's going on when you can't see certain sites, etc.

-John Q.
John I. Quebedeaux, Jr.; Louisiana State University
Computer Manager LBRN; 131 Life Sciences Bldg.
e-mail: johnq at lsu.edu; web: http://lbrn.lsu.edu
phone: 225-578-0062 / fax: 225-578-2597

> From: David Callahan <david at bunnywood.org>
> Date: Tue, 11 Jan 2011 16:13:16 -0600
> To: <ag-tech at lists.mcs.anl.gov>
> Subject: [AG-TECH] I broke something on my video. Need help!
> I have a private 4 node AG set up very simply with Ubuntu computers,
> Logitec webcams, and some large TVs. I still have a LOT to learn about
> this software, so bare with me as I muck through this, please.
> I'm not sure what I touched, but video was working, and now I see only
> my own video. Other nodes see all nodes but me. My computer is also the
> server for the group. We are all connected to the same lobby. We can see
> each other as participants.
> I really need to fix whatever I've done before Wednesday 3pm central.
> What info do I need to locate to find out what's going on?
> I appreciate any help!

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