[c-nsp] FabricPath & PIM-SM Interoperation

[Yuri Bank]

Hi Tim,

Thanks for your response.

I should have phrased my question differently. I'm not suggesting that FP
IS-IS actually interacts with PIM-SM directly.

My question is:  Will the FP device, which is running PIM-SM on some SVI,
send PIM Register/Join messages for learned multicast sources/receivers in
the FP domain?

Imagine the following scenario.

You have DeviceA and DeviceB.

DeviceA is a FP switch, with an entire FP domain behind it.
DeviceB is a legacy multilayer switch, or router, with many other L3
devices behind it.

DeviceA has an FP-VLAN with a PIM-SM enabled SVI in it.
DeviceB simply has a layer3 interface (in the above vlan) with PIM-SM
enabled.

Now the RP, sits somewhere behind DeviceB. Obviously, if there is a host
somewhere in the FP network that starts sending multicast traffic, DeviceA
will have to send out a PIM-Register message in order for the RP to learn
of the source(otherwise, only hosts in the FP network would be able to
listen to that traffic). Likewise, if there is a multicast receiver in FP
network, a PIM-Join message would need to make its way to the RP.

Does this make sense? Again, I greatly appreciate your response.

-Yuri Bank



On Tue, Sep 17, 2013 at 9:46 AM, Tim Stevenson <tstevens at cisco.com> wrote:

> Hi Yuri, please see inline below:
>
> At 03:27 AM 9/17/2013  Tuesday, Yuri Bank clamored:
>
>  Hello fellow networking enthusiasts,
>>
>> I have a few specific questions concerning this:
>>
>> 1. *Will a N7k/N5k translate GM-LSPs into PIM-Join messages, on a boundary
>> link that has a remote peer running PIM-SM?
>>
>
>
> No. FP ISIS GM-LSPs are an L2 concept here, they basically track group
> membership state at L2 inside the FP core. FP ISIS would not "peer" with a
> router running PIM-SM; you would typically have an SVI enabled for the FP
> VLAN, and that would have PIM enabled to integrate to L3.
>
>
>
>  2. *Same question as it relates to sources learned, that are within the
>> FabricPath domain. Will PIM Register messages be generated, and sent to
>> the
>> RP in the PIM-SM domain?
>>
>
>
> Not without an SVI/router interface running PIM connected into the FP
> domain.
>
>
>
>
>  3. *Any general information regarding this topic would be greatly
>> appreciated, as I could find very little documentation about this.
>>
>
>
> Think of FP GM-LSPs as an extension of IGMP snooping. All the L3
> integration is basically the same in FP and classical Ethernet.
>
>
> Hope that helps,
> Tim
>
>
>
>
>
>  Regards,
>>
>> YuriB
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>
>
>
> Tim Stevenson, tstevens at cisco.com
> Routing & Switching CCIE #5561
> Distinguished Technical Marketing Engineer, Cisco Nexus 7000
> Cisco - http://www.cisco.com
> IP Phone: 408-526-6759
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