Subject: multicast routes when there's no default
To: None <email@example.com>
From: Ed Ravin <firstname.lastname@example.org>
Date: 08/17/2000 12:26:40
I've been playing around with routed trying to get it to pick the best
route based on IRDP information received over the network.
The first thing I noticed is that when I delete the default route (so
that routed will give me a new one), multicast routing no longer works.
This makes routed unhappy, since it tries to find routers via sending
a router solicitation to 22.214.171.124 (all-routers.mcast.net), and if it
can't send a multicast packet, it marks the interface as "SICK" and
we now have to wait until a router advertisement appears on the segment.
After some surfing, I found a couple of posts that suggest creating a
route for multicast packets to the loopback interface with:
route add -net 126.96.36.199 127.0.0.1
But that effectively throws the packets away - at least on the NetBSD 1.4
and 1.5 where I tried it.
I suppose I could always add a route before I start routed that points
all multicast traffic to the local subnet, but what if I have two
physical interfaces? Wouldn't you want a broadcast to "all-routers" to
go to all physical interfaces?