[c-nsp] Need help with setting up ip multicast routing...correction

[Lee]

On 10/12/10, Gert Doering <gert at greenie.muc.de> wrote:
> Hi,
>
> On Mon, Oct 11, 2010 at 04:35:24PM -0400, Matthew Huff wrote:
>> If the switch doesn't provide layer 3 services (routing) itself, but is
>> really a l2 switch, then you don't need multicast routing / pim,
>> etc...However, you should have igmp snooping on.
>
> IGMP snooping won't help for router-switch-router traffic.
>
> "No IGMP there"

I thought the problem on router-switch-router multicast traffic was
that IGMP snooping didn't limit multicast traffic.  I've never
connected up routers through a 2950 (which is what the OP is using -
right?), but it looks like igmp snooping on a 2950 does learn the
ports going to PIM routers:

c2950>sh ip igmp snoop
  [.. snip ..]
Vlan 1:
--------
IGMP snooping                       : Enabled
Immediate leave                     : Disabled
Multicast router learning mode      : pim-dvmrp
Source only learning age timer      : 10
Last member query interval          : 1000
CGMP interoperability mode          : IGMP_ONLY

Lee