[LARTC] multicast over GRE tunnel

[Steve Eckmann <eckmann@computer.org>]

I need to send multicast traffic through a GRE tunnel between two Linux 
routers. The tunnel works for normal IP packets, but I can't see how to 
make it work for multicast. Here's the setup:

                        10.10.10.0/24
 LAN-B--------------RtrB-------------RtrC--------------LAN-C
      192.168.2.0/24                     192.168.1.0/24

 RtrB interfaces:
   eth0 192.168.2.1
   eth1 10.10.10.11

 RtrC interfaces:
   eth0 192.168.1.1
   eth1 10.10.10.201

 Tunnel setup on RtrB:

   ip tunnel add netC mode gre remote 10.10.10.201 local 10.10.10.11
   ip link set netC up
   ip addr add 10.10.10.11 dev netC
   ip route add 192.168.1.0/24 dev netC

 Tunnel setup on RtrC:

   ip tunnel add netB mode gre remote 10.10.10.11 local 10.10.10.201
   ip link set netB up
   ip addr add 10.10.10.201 dev netB
   ip route add 192.168.2.0/24 dev netB

I'm stuck here. I tried adding routes for 224.0.0.0/4 and for a specific 
multicast group (say 239.16.2.2) to the netB and netC "devices", but the 
multicast traffic isn't getting out of its source LAN. Are there ip 
commands that will do it? Do I need additional software running for 
multicast? I couldn't get mrouted or pimd to compile on Fedora Core 4. I 
installed xorp but haven't tried running it yet because I'm very 
confused about what is needed, besides the basic kernel and iproute2, 
for a multicast-capable Linux router.

Thanks.
_______________________________________________
LARTC mailing list
LARTC@mailman.ds9a.nl
http://mailman.ds9a.nl/cgi-bin/mailman/listinfo/lartc