[c-nsp] Need help with setting up ip multicastrouting

[Phil Mayers]

On 10/13/2010 08:37 AM, Gert Doering wrote:
> Hi,
>
> On Wed, Oct 13, 2010 at 08:18:47AM +0100, Phil Mayers wrote:
>> On 10/12/2010 09:46 PM, Gert Doering wrote:
>>> On Tue, Oct 12, 2010 at 02:59:28PM -0500, Christopher.Marget at usc-bt.com
>>> wrote:
>>>> The switch listens to the following messages in order to detect router
>>>> ports with IGMP snooping:
>>>> · IGMP Membership query send to 01?00?5e?00?00?01
>>>> · PIMv1 hello send to 01?00?5e?00?00?02
>>>> · PIMv2 hello send to 01?00?5e?00?00?0d
>>>> · DVMRP probes send to 01?00?5e?00?04
>>>> · MOSPF message send to 01?00?5e?00?05 or 06
>>>
>>> Thanks for clarifying this.  Indeed, with this information, IGMP snooping
>>> should never be harmful for router-switch-router traffic.
>>
>> That is not my experience.
>
> Can you share details?

Sorry, I did realise after sending that it was too terse to be useful.

Essentially I've observed exactly the behaviour you described in a 
previous email. Two PIM routers either side of a layer2 switch would 
fail to pass any routed multicast traffic because IGMP snooping was 
enabled and was "eating" it. PIM snooping was the solution I decided I 
needed, but it was easier to just remove the switch and go for a direct 
link in that case.

Now I must admit: when I think about it, I don't know what model the 
layer2 switch in question was; it may not even have been a Cisco (this 
was some time back) in which case Christopher may also be right ;o)