[AG-TECH] Unicast-Multicast bridges?

Stuart Levy slevy at ncsa.uiuc.edu
Tue Jan 22 11:45:50 CST 2002

Oh, OK.  In case you need to bridge between two multicast clouds
that aren't otherwise multicast connected, you could 
use two copies of the bridge, one per cloud, like:

  <on "insidehost">
     udpbridge -p 8666  insidemcast/8666/ttl  outsidehost/8666

This forwards any traffic sent to "insidehost" or to the
"insidemcast" group to (a) any other such participants and
(b) via unicast to outsidehost.

  <on "outsidehost">
     udpbridge -p 8666  outsidemcast/8666/ttl

This forwards any outside traffic to whatever participants
outsidehost sees.  If there are any inside participants,
then outsidehost will see traffic from insidehost
and will send outside traffic there too.

Here "insidemcast" and "outsidemcast" had better either
  - be different multicast addresses, or
  - be *really* not connected by any other means,
or there'll be a routing loop, very bad news!

So using pure unicast may be safer.  You could use a similar
trick, just omitting the mcast address on the "insidehost" side,
to avoid that ugly possibility.


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