Multicasting over a router

In order to multicast over a router/VLAN some configuration to your routers may be required. Below are a few vendor specific examples:

Cisco 2800 Series:

!
interface FastEthernet0/0
ip address 1.1.x.x 255.255.255.0
ip helper-address 10.10.10.2
ip pim sparse-dense-mode
duplex auto
speed auto
!
interface FastEthernet0/1
ip address 10.10.10.11 255.255.255.0
ip pim sparse-dense-mode
duplex auto
speed auto
!

more information http://www.cisco.com/en/US/tech/tk828/technologies_tech_note09186a0080094821.shtml