Morning all. I was wonderign if anyone could comment on how deployed is
multicast routing in real-world networks. How many of you have enabled
multicast routing in your core routers? Do you offer this as a service to
your customers? If no, why not? Do you plan to? The problem with IP
multicasting is that is not usefull unless everyone is usinging it. I'am
wondering when we will start seeing it in use. New products are starting
to support multicast (new CUSeeMe, etc) but the infrastructure doesnt seem
to be there.

Aleph One /
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All the sites that I'm familiar with are still using tunnels. Some of
those tunnels might be homed on dedicated routers instead of a
Unix/mrouted machine, but I'd be somewhat suprised if anybody ran
native multicast in their core routers.

People pay for unicast traffic, and its not worth messing up that
unicast traffic for a fun multicast experiment that'll crash your
router or run it out of memory ever other day.

While this statement was true not all that long ago, it doesn't hold water
with the more recent code, at least from a particular router vendor that I
tend to deal with.

There are also more knobs to protect yourself with (and also hang yourself
with, but that's as it should be. :)) these days.

We run native multicast on our core routers, and the decision to do this was
based on scalability. Dozens of tunnels doesn't scale very far. Also, the
ability to do sparse mode PIM lessens the load you put on your infrastrucutre.

I'm also of the opinion that the congruence between unicast and multicast
topology (at least as much as you can do it) is a good thing.

As far I know, there are quite a few folks running native multicasting on
their routers, even though it's still a minority.