[TriLUG] Multicast across VLANs - Cisco Specific

[Ryan Leathers]

I don't think what you are trying to do is possible.

There are two interesting things you can do with multicast on your Cisco 
gear using IGMP and MVR. Neither of these does what you are after. 
Google for IGMP snooping.  This lets you control where multicast traffic 
goes within a VLAN. MVR lets users stay in separate VLANs and also 
subscribe to the multicast.

It sounds like what you want is to bridge VLANs by making a routing 
decision based on multicast traffic. Is that right? Is that REALLY what 
you want or is that just an idea cooked up for bridging VLANs?









On 4/6/10 11:31 AM, Kristopher Kane wrote:
> Hello Trilug,
>
> I am having trouble piecing together multicasting between two 3750G
> switches.  Here is my situation:
>
> I don't have control over switch 1.  I have control over switch 2.
>
> Switch 1 has vlan 1 with multicast traffic.  Switch 2 has vlan 2. Switch 1
> and Switch 2 do not have a trunking protocol between them.
>
> I would like to connect the switches with access ports and have switch 2
> listen for the multicast traffic from switch 1:vlan 1, then use the L3
> capability of the switch to route the multicast traffic to the remaining
> access ports of switch 2 that are on vlan 2.
>
> I know I am asking to do a hackish thing without a trunk and if you have
> read this far I appreciate your attention to this off-topic subject.  I
> respect the broad range of knowledge that this group holds and hope someone
> can tell me: "Hey, dummy! This has to be done at the router with IGMP/PIM"
> or "Sure, try this..."  I am fairly certain that the access port must
> "subscribe" to a specific multicast feed which will throw my idea out the
> window anyway.
>
> Thanks,
> -Kris
>