I'm trying to get mrouted working between two 3.0 hosts which are linked 
with an OpenVPN tunnel. Both hosts are running as NAT gateways for their 
respective internal networks. Routing is set up over the OpenVPN tunnel 
correctly (i.e. any machine on 192.168.0.0/24 on one site can talk to 
192.168.1.0/24 on the other).

One end has:
name LOCAL 239.255.0.0/16
phyint ex0 boundary LOCAL
tunnel 192.168.0.254 192.168.1.254

The other:
name LOCAL 239.255.0.0/16
phyint fxp0 boundary LOCAL
tunnel 192.168.1.254 192.168.0.254

mrouted -d 3 at each end shows they are speaking:
20:12:58.881 SENT neighbor probe     from 192.168.0.254   to 224.0.0.4
20:12:58.881 SENT neighbor probe     from 192.168.0.254   to 192.168.1.254
20:13:01.796 RECV route report       from 192.168.1.254   to 192.168.0.254
20:13:01.796 Updating 4 routes from 192.168.1.254 to 192.168.0.254
20:13:01.832 RECV neighbor probe     from 192.168.1.254   to 192.168.0.254

tcpdump -ni tun0 (i.e. the OpenPVN link) shows the multicast traffic is 
being forwarded over the link each way:
20:09:44.687152 IP 192.168.1.254 > 192.168.0.254: IP 192.168.1.1.50141 >
 	239.255.0.1.1000: UDP, length: 417 (ipip-proto-4)
20:09:44.688759 IP 192.168.0.254 > 192.168.1.254: IP 192.168.0.254.64526 >
 	239.255.0.1.1000: UDP, length: 1023 (ipip-proto-4)

However, on the local networks only the local multicast traffic is seen, 
the tunnelled packets are not forwarded. There's probably just some silly 
step I'm missing. Any ideas?

-- 
Stephen