I am trying to configure my machine (Pentium 90, running NetBSD1.2),
to act as a multicast router.  The problem is, the machine has only one
ethernet interface.  If it receives a multicast packet on that
interface, can it forward the packet to a *small group* of machines on
the same subnet?  (Note: I don't want it to forward to all
the machines on the same subnet since that would involve the machines
of pretty much the whole department).

Going through the man pages of mrouted, I found that it needs at least
two 'virtual interfaces'.  One way to have two virtual interfaces is
to have 2 physical cards.  The other is to create a 'tunnel' between
my machine and a router *outside* my subnet.  I tried the second
approach (by creating an /etc/mrouted.conf file) and running mrouted
on my machine and changing the /etc/mygate on the other group of
machines.  I found the first router outside my subnet by running
traceroute and created a tunnel to it.  However, then I am unable to
talk to the external world.  I am pretty sure that other router also
needs to be running mrouted, but I have no idea how to find the
neighboring routers that are running it. 

Can anyone suggest a fast way to set up my machine as a multicast router ?

Thanks a lot,
Aman

-- 
Aman Sinha <sinha@ece.utexas.edu>
Electrical and Computer Engg.
Office: ENS 406, U of Texas at Austin, Austin, TX 78712.
Ph: 512-471-8011