[AG-TECH] Bridge server

Andrew Sharpe andrew.sharpe1 at jcu.edu.au
Wed Apr 19 21:12:58 CDT 2006


It looks as though you're using the PersonalBridge and if so then you 
should be aware that the PersonalBridge listens on an extra port for 
each bridge.  This means for a single venue you'll be using 6 ports 
(instead of 4 with QuickBridge).  You should also be aware that the 
extra port opened is the base unicast port + 5.  Direct from 
BridgeServer.py (after patched for PersonalBridge)

    self.cport = uport + 5

Thus if you put a couple of bridges in close range then you're likely to 
come up with conflicts.  Before anyone tries to tear me a new one, I am 
aware that the above line is not intelligent.  I think the patch that 
Michael Braitmair has written would be a good start to alleviating this 
problem - but I'm not trying to pass the buck.  This is a problem in the 
patch we're using for PersonalBridge and we will fix it.

HINT: If you're using linux then you can see what processes are 
listening on what tcp ports with the following command (as root)

    netstat -tlp

Maybe this sheds some light on the situation, maybe not.  Either way I 
will still have a go at implementing a more intelligent port choice for 
the extra port in PersonalBridge.

Thanks, Andrew

Jeremy Mann wrote:

>So basically I have to manually bridge each room. In my config file I
>tried to set the entire VenueServer to only use a range of ports, then I
>entered ports for the rooms I wanted to configure statically. But I still
>came across that "Address already in use" problem.
>For example, I have the VenueServer set to 5000-5200 and 4 Venues to 5202
>on up.
>Michael Braitmaier said:
>>I am doing basically the same. I restrict the range of the ports for
>>unicast for a specific venue.
>>Config-File example:
>>One of the problems rising with this configuration method is that
>>normally AG selects ports on a random
>>pattern put of the range you specified in the config file.
>>Ports for rat and vic are allocated sequentially.
>>So first rat gets assigned 50096 for example.
>>When the port for vic should  be determined, it can happen due to the
>>nature of the random allocation
>>that for vic also 50096 is initially selected. This of course leads to a
>>"Address already in use" error.
>>I avoided the problem by patching the AccessGrid files responsible for
>>port allocation to keep a list
>>of ports which are in use and have the allocation algorithm first check
>>if a port the algorithm wants to allocate
>>isn't in use yet.
>>Otherwise you have to restart the bridge server until you don't get the
>>"address already in use" error to be sure you really have
>>video and audio correctly bridged.
>>Jeremy Mann schrieb:
>>>Thomas D. Uram said:
>>>>Which version of AG software are you using for BridgeServer and
>>>>Can you post your full bridge cfg file?
>>>AG 2.4. Attached is the config file. Worth noted is that I no longer get
>>>those python errors, however, now when I start it, several of the venues
>>>aren't bridged because the bridgeserver says the address is already in
>>Dipl.-Inf. Michael Braitmaier
>>HLRS - Visualization / Video Conferencing
>>University of Stuttgart
>>Phone: ++49 711 685 5996
>>Fax  : ++49 711 682 357
>>Website: http://www.hlrs.de/people/braitmaier/

Andrew Sharpe
APAC Project Officer
James Cook University Townsville
ph: +61 7 4781 4084

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