Inter-vlan Multicast Routing

Routing & Switching Multicast
1

Good Day,

I have an interesting issue that I inherited via a consultant who was not well versed on the system he was working on. I have to route multicast traffic to different vlans from the source vlan. The source of the multicast is in network 172.25.135.0/25, however the end devices are located as follows:

172.25.132.192/26
172.25.132.128/26
172.25.133.192/26
172.25.133.
172.25.133.64/26
172.25.133.0/26
172.25.134.192/26
172.25.134.64/26
172.25.134.0/26

There are no routers in use only Cisco 9300 series. Without a router acting as a querier, I would have to enable multicast routing on each switch, enable igmp snooping on each vlan, and PIM on each vlan interface:

ip multicast-routing (global config each switch)

interface vlan XX (interface config for each vlan wanting to receive multicast traffic)

ip igmp snooping
ip pim sparse-dense-mode

I would prefer to move this all to one vlan and re-ip the devices to make it easier, but alas!!

2

Hello Ralph

Yes, you are correct. If there is no router acting as a querier, then what you describe should work:

  • Enable multicast routing
  • Enable IGMP snooping
  • Activate PIM

Take a look at the Multicast course below that deals with all of these issues in detail:

That too would be a solution, however, you must make sure that you are not creating an excessively large broadcast domain. If the number of hosts is small enough, then yes, otherwise it is best to keep the segmentation of the network as is.

I hope this has been helpful!

Laz