Multicast Routing between vlans on layer 3 switches without a Router

[jamy66]

Hi

I have a network with 5 access switches connected directly to a cisco 4500, also i have enabled intervlan routing globally so communication between different VLANS with different subnet is not an issue 

as im new to the subject just want to know how can i proceed with multicast routing between VLANs in my environment.

will enabling IGMP on all the switches be enough or do i have to do some other configurations

thnx

[Jon Marshall · Accepted solution]

IGMP snooping should be enabled by default so nothing to do on access switches. 

On the core switch you need to - 

1) enable multicast routing "ip multicast-routing" 

2) on each of the L3 vlan interfaces enable PIM eg.  "ip pim dense-mode" or "ip pim sparse-mode". 

If you configure sparse mode you need an RP as well which would be your core switch in this case. 

Jon

[jamy66]

thanks Jon

just want clarification regarding adding a RP

so in each VLAN interface i enable PIM sparse

ip pim sparse-mode

assume that my interfaces for core switch for VLAN 1 is 192.168.10.10

and vlan 2 is 10.10.10.5

do i have to assign the RP ip address in access level switches as well or only in the core under each VALN interface if i configure the RP ip address will it be enough

eg:- for vlan 2

 ip pim rp-address 10.10.10.5     

thanks

[Joseph W. Doherty · Accepted solution]

The PIM RP is only needed on other multicast routers, it's not used on L2 only devices.

I recall (?) it's a global parameter, not an interface parameter. You can have more than one, though, for different multicast address blocks.