Cisco; Multicast

In 2008, we needed to allow multicast on our vpn infrastructure. This setup was mostly done with a little cisco router at the client side, and one big one on our side. You can find here the basic configuration that we used in an existing setup.
Some configuration that needs to be done on the vpn-box (fe a cisco router 876).

ip multicast-routing
interface Tunnel0
ip pim sparse-mode
!
interface Tunnel1
ip pim sparse-mode
!
interface Vlan1
ip pim sparse-dense-mode
!
interface Vlan2
ip pim sparse-mode
!
ip access-list standard rp1-grp
permit 224.0.52.0 0.0.0.255
ip access-list standard rp2-grp
permit 224.0.53.0 0.0.0.255
!
ip pim rp-address 156.48.121.2 rp1-grp
ip pim rp-address 156.48.121.55 rp2-grp
ip mroute 156.48.0.0 255.255.0.0 Tunnel1

And some configuration on the vpn-concentrator (fe cisco router 2691)

ip nat inside
ip pim sparse-dense-mode
ip igmp join-group 224.0.52.1
ip igmp join-group 224.0.52.3
ip igmp join-group 224.0.53.1
ip igmp join-group 224.0.53.3

Note: Of course, change the ip’s with the proper ip’s of your network.

How can you now test if the mutlicast is coming in?

sh ip mroute (see if the dedicated group is in there)
sh ip mroute count (see if any packets are passing by)
sh ip igmp membership all (who’s asking what?)

I hope that it works for you as good as it works for me…
This can only goes 2 ways, you’ll enjoy it or you’ll get a big headache…