[AG-TECH] Loopback Multicast and linux

Piers O'Hanlon p.ohanlon at cs.ucl.ac.uk
Thu Oct 27 13:15:15 CDT 2005

Hi John,

> Relating this particularly to using VP, although it does apply to vic 
> as well.
> Under linux vic doesn't loopback the multicast to the localhost, so in 
> the VP
> window I can't see my own video.  I've done a simple 3 line hack to 
> vic to
> make this work, but was wondering if anyone else had comments on what the
> default behaviour should be.
> Do people reckon this should be a commandline option to vic?

There are some many different things that one might want to control - 
it's debatable if we want it a command line option.

You can tell vic to loopback its packets by creating a file in your home 
dir called ".vic.tcl" and putting the following into it:

exec wish4.2 "$0" "$@"
proc user_hook {} {
global V
# allows reception loopback of packets
$V(session) loopback 1
# allows loopback of packets
$V(data-net) loopback 1
$V(ctrl-net) loopback 1

When you next start vic it will send packets out of the loopback 
interface (and display two local video windows - u can get rid of the 
second video window by commenting the "$V(session) loopback 1" line.


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