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multicast layer 3 switch with ipbase

I have a Layer 3 switch that is running ipbase feature set. On this switch i have 4 VLANs 2 voice and 2 video. There is a trunk from this switch to another switch. I have enabled ip multicast-routing on the L3 switch. I have IP paging speakers that "rely" on multicast to work. The source comes from a paging relay that then sends out the multicast to the speakers. One speaker is in the same VLAN as the paging relay and works fine (they are both on the layer 3 switch directly). The other speaker is in a different VLAN on the trunked switch. When we send a page to the second speaker, we get no audio. 

I'm trying to determine if it's an issue with my multicast configuration or with the IP speaker's configuration.

As a note since i'm running IPBASE I cannot run the ip pim sparse-dense on the VLAN interfaces of the Layer 3 switch.  However if i run the command show ip pim interface all of my vlan interfaces are displayed. Likewise if I run the command show ip igmp snooping group it shows several multicast groups some of which are present it several vlans.

I can provide run configs of the switches for more detail, but someone may have an immediate idea without them so just let me know!

Everyone's tags (1)

Hello,  So just to make sure.




So just to make sure.



A network composed of 2 switches.


1 running on L3 mode and the other a L2 switch.



You need to send the Multicast stream over 2 different VLANs (one locally on the L3 switch and the other gets down via the L2 switch).



If that's the case as long as you are running PIM on both of the VLANs I do not see any problem at all.


You already checked the show ip pim interface which is good and let us know PIM is enabled everywhere required.


Do you see any useful entry when sending the page?


I mean run a show ip mroute and make sure you see in the OIL the required VLANs.





Julio Carvajal
Senior Network Security and Core Specialist
Community Member

All of your assumptions about

All of your assumptions about the network layout are correct.

What do you mean by "useful information" i'm not on site, so i can't easily do a packet capture.

What do you mean by OIL?

Here is the mroute output for the multicast group i'm interested in:

(*,, 21:04:52/00:02:32, RP, flags: DC
  Incoming interface: Null, RPF nbr
  Outgoing interface list:
    GigabitEthernet1/1/1, Forward/Sparse-Dense, 21:03:38/stopped
    Vlan4, Forward/Sparse-Dense, 21:04:52/00:02:30
    Vlan2, Forward/Sparse-Dense, 21:04:52/00:02:32


And here is  output for the command sh ip igmp membership

 *,            1d08h    02:51 2A     Vl4
 *,            1d09h    02:51 2A     Vl2



With these outputs is it safe to say that the L3 switch is correctly seeing the clients register to the Multicast group, and that when traffic destined to that multicast address, it will be sent to those two vlans?

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