[AG-TECH] Bridge availability chances.

Paul Mercer mercer at arsc.edu
Mon Apr 9 16:41:01 CDT 2007

Thanks, the cached bridge list and the update bridge registry in 3.1  
will be  nice features.

thanks for the update.


On Apr 9, 2007, at 1:06 PM, Christoph Willing wrote:

> On 10/04/2007, at 5:38 AM, Derek Piper wrote:
>> 	I'm having a (possibly) similar problem with a participant in  
>> Tokyo, Japan. I'm not sure of the way that bridges are chosen, but  
>> it seems that from this participant's location, no bridges are  
>> available at all. I'm not sure if it's firewalling or what that  
>> might prevent even the LIST of bridges appearing, or what it is.
> At present, all AG3 bridges are "advertised" via a single bridge  
> registry (at ANL) and collected into the VenueClient's bridge list  
> when it starts up. If the bridge registry is not contactable, for  
> whatever reason, at startup then the VenueClient will have an empty  
> bridge list. Often, restarting the VenueClient will result in a  
> usable bridge list - it depends on why the registry wasn't  
> contactable; it could be that the registry was down, or maybe a  
> local network problem. As long as the bridge registry isn't  
> contactable, there'll be an empty bridge list.
> AG3.1 (real soon now) caches bridge lists so that the cached  
> version can be used when the bridge registry is not reachable at  
> start up. It also has an update facility i.e. update bridge list  
> while VenueClient is running.
> The AG2 bridge mechanism is quite different - for a particular  
> venue, a site somehwere must be running a bridge server which  
> explicitly targets that particular venue in its configuration file  
> (AG3 bridges bridge all venues).
> chris
>> Jimmy Miklavcic wrote:
>>> I'm working with Kansas University Medical Center to get a small  
>>> Access  Grid node running. They most certainly don't have  
>>> multicast available on their campus so we are stuck with unicast.  
>>> They have a "very" stringent security policy and I'm forced to  
>>> narrow down the number of bridges that they will allow through  
>>> their fire wall.
>>>  So the question is, if I give them a list of ten bridges, what  
>>> are the chances that one or two of them will be listed in the  
>>> bridge registry? Should they increase their bridge locator  
>>> function from 10 to say 20 to increase their chances of seeing  
>>> any of the ten? Also, if a bridge is not listed in the registry,  
>>> does it mean that it is not available?
>>>    -- Jimmy Miklavcic
>>> Multimedia Specialist
>>> Jimmy.Miklavcic at utah.edu
>>> 155 SOUTH 1452 EAST RM 405
>>> SALT LAKE CITY, UT 84112-0190
>>> Office: 801.585.9335
>>>  Fax: 801.585.5366
>>> http://www.anotherlanguage.org
>> -- 
>> Derek Piper - dcpiper at indiana.edu - (812) 856 0111
>> IRI 323, School of Informatics
>> Indiana University, Bloomington, Indiana
> Christoph Willing                       +61 7 3365 8350
> QCIF Access Grid Manager
> University of Queensland

Paul Mercer
Arctic Region Supercomputing Center
907 450 8649

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