Multicast routing

[Andrew Snare <ajs_(_at_)_pigpond_(_dot_)_com>]

Hi,

At home I use a mini-itx box with OpenBSD-3.3 installed as a firewall/NAT
box for my ADSL connection. My ISP recently started offering TV using
multicast, so I figured it was time to try and get multicast routing
going (and even figure out an appropriate pf ruleset).

I've set in /etc/rc.conf the appropriate options:

multicast_router=YES                            # Route IPv4 multicast traffic
mrouted_flags=""                                # .. with nothing special

And configured the following in /etc/mrouted.conf:

name LOCAL      239.255.0.0/16  # Local-scoped groups
name ORG        239.192.0.0/14  # Organisation-scoped groups
phyint tun0 boundary LOCAL boundary ORG

My upstream interface is tun0 (we have to use pptp... but that's a rant
for another day... suffice to say I got it working with userland ppp).

I have two problems:

1) mrouted refuses to acknowledge tun0 as a multicast interface since it has
a /32 netmask. Looking at the code for mrouted yields no obvious reason for
this, although the code seems to date back to '95 when maybe point-to-point
links weren't as common.

2) If I try to configure a tunnel with the 'tunnel' command, it doesn't find
my upstream router. I _know_ that upstream supports multicast since they need
it for the trial they have underway. Using the tunnel option seems to send
DVMRP packets upstream, but nothing comes back. This seems to be a fairly old
protocol for multicast routing, and it's possible upstream hasn't been
configured to use it.

My questions are thus:

a) Is anyone else actually using mrouted, preferably in a situation
resembling my own?

b) Is there some other routing daemon that I can use instead? I've tried
using zebra but it seems to only use multicast at the link level to talk
with other routers. Does it actually function as a multicast router as
well?

Thanks in advance for any light that can be shed on the matter.

 - Andrew