[cisco-voip] Multicasting Speakers and Feed IP command

[Ian J. Pitts]

You will need to have ip pim on every layer 3 hop interface.

If I read your email correctly you have a 3845 with a dot1q interface  
serving both vlan 10 & 999. This is fine provided the 3845 has  
multicast routing enabled and both vlan interfaces on the 3845 for  
vlan 10 and 999 have ip pim enabled.

If you have any other layer 3 hops between the devices those vlan  
interfaces will also need ip pim.

Ian

Sent from my iPhone

On Jan 22, 2010, at 4:11 PM, "Robert Kulagowski" <rkulagow at gmail.com>  
wrote:

> Ian J. Pitts wrote:
>> The only way to get from vlan 999 to vlan 10 with multicast is to  
>> route it
>> and that requires multicast routing on the router.
>>
>> If you are using the 3750 for layer 3 routing you will need to  
>> upgrade to an
>> image that supports it.
>> You could also add another router to those vlan's and enable  
>> multicast
>> routing and ip pim on those layer 3 interfaces.
>>
>> Just to clarify the audio path.
>> When you enable the feed ip dn you are essentially having the cme  
>> instruct
>> the calling phone to send it's audio to a multicast address. The  
>> packets are
>> sourced from the calling phone not the CME. This might be the part  
>> that is
>> causing the confusion.
>
>
> Still trying to work through it...
>
> OK, so the router has pim sparse-dense on the two dot1q subinterfaces.
>
> If the phone is in vlan10, and multicast routing is enabled on the  
> 3845,
> then shouldn't that be sufficient to get multicast packets to vlan999
> (and thereby extended over the trunk to the 3750)
>
> There are ip addresses assigned to the two VLANs that exist on the  
> 3750
> (they're 10.255.3.5 and 10.244.3.5; the dot1q on the router is .1 in
> both subnets)
>
> I'm not doing any layer 3 routing per-se on the 3750; it's pretty much
> router-on-a-stick configuration.
>
> I'm not looking to add another router into the mix; I'd like to use  
> what
> I already have.
>
> In any case, I've installed the ip services image onto the 3750, so  
> lets
> see what happens.  Do the two vlan interfaces on the stack master also
> need to have the pim sparse-dense-mode command?