well-know multicast groups

[Shuqian Yan <syan@jupiter.nal.utoronto.ca>]

Hello, all

This is a question about the use of well-know groups(WKG) with local
multicast/broadcast. 

If I want to broadcast a message to all the routersin the topology, 
all I need to do is to specify the $agent dst_ ALL_ROUTERS??
Can I assume that ALL_ROUTERS is already registered/defined in the
McastProto.tcl under class mrtObject? or do I need to do something  before
using it?

So once I set the <$agent set dst_ [ALL_ROUTERS]>, the message will be
automatically broadcast to all routers in the topology. and if I set the
message pkt ttl value to a relatively small value (the current default
ttl_ 32), then the message will basically get routed around a circle
limited by the ttl scope.

Any help is appreciated,

shuqian