I have applied these to the code in the AG cvs repository under the module ag-media. This is a unified module representing ag-vic and ag-rat (but now we only have to keep one copy of the common library and tcl and tk :-). We'll be sure to include this in the next release ;-) --Ivan

-----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Andrew Swan Sent: Monday, January 26, 2004 8:44 PM To: Don Morton Cc: Sergeant A. G. Tech; Jennifer Parham; [email protected]; [email protected]; Dan Schmiedt; [email protected] Subject: Re: [AG-TECH] Unicast issues with vic/rat

Don Morton wrote:

...

For some reason, there are folks who are trying to unicast in, and the end result seems to be that "we" can see them, but they can't see us. Note that there's no multicast involved here - in one case, the bridge is simply being used as a "rendezvous point" for two unicast streams, but the same problems occur - I seem to be able to see/hear the remote site, but they can't see/hear me.

[...]

My vague understanding of vic/rat, used with the QuickBridge, is that the clients send UDP datagrams out to the bridge on ports in the 50000 range, and they seem to receive UDP datagrams on ports in the 32000 range, and it "should" be that simple.

i'm not sure about rat but vic in unicast mode sends and receives on the same port, which is specified on the command line. (the ports in your example were in the 50000 range). the source port in packets sent from vic will be an "ephemeral port" chosen by the operating system which is likely what you are referring to as in the 32000 range.

the behavior you describe is consistent with a nat or a firewall that builds dynamic rules that assumes vic will receive packets on the same port that it sends them from.

for example, if the remote person joins your quickbridge on port 50186, they start sending packets from source port 32456 (or some other port chosen by their operating system, but not port 50186). upon seeing these packets, the nat or firewall installs a rule to forward packets from source port 50186 on the quickbridge addressed to destination port 32456 back to the remote participant. however, quickbridge is sending packets to destination port 50186 so they never reach the remote site.

probably the easiest way to verify that this is the problem is to rebuild vic with the attached patch and run the modified version at the remote site. or if you have openmash vic installed, you can just add the flag "-rtptv" to the vic command line to get the same effect.

-Andrew