IP Multicasting

Unanswered Question
Jul 17th, 2007

I've read through many of the IP Multicasting issues but still can't get mine resolved so I thought I'd give this one more shot.

We have two VLANs on our network (data - VLAN 1, and voice VLAN 23). The core switch is a 4510 and the IDFs are 3560's. I have configured IP MultiCasting on the 4510 and the 3560 I am testing with. VLAN 1 data vlan is subnet and voice (vlan 23) is We have our call manager set up on and our phones all register and work correctly. Have a helper address set up ont he core switch. I have set up each vlan on the core and the 3560 as follows:

interface Vlan1

ip address

ip pim sparse-dense-mode


interface Vlan23

ip address

ip helper-address

ip pim sparse-dense-mode

I have also tried different modes for IP PIM but no success.

This is for a berbee (informacast) paging system that requires multicast. Any assistance would be very much appreciated.


I have this problem too.
0 votes
  • 1
  • 2
  • 3
  • 4
  • 5
Overall Rating: 0 (0 ratings)
johnnylingo Wed, 07/18/2007 - 12:25

I can tell you that Multicast is disabled by default on the 4500. Turn it on with "ip multicast-routing"

Also try these commands to troubleshoot.

"show ip multicast"

"show ip multicast interface"

"show ip pim interface"

"show ip pim neighbor"

"show ip igmp groups"


This Discussion