[c-nsp] Why does PIM enable IGMP?

[Keegan Holley]

Isn't it also technically possible to have receivers and routers on the same link?  Maybe they (ciscos developers) were just trying to be helpful.  Kind of like that little paper clip from MS office.  

Sent from my iPhone

On Feb 28, 2011, at 10:36 AM, John Neiberger <jneiberger at gmail.com> wrote:

> I know what they are for individually, but I was wondering why IGMP is
> automatically enabled when PIM is enabled. My thought was that there
> was no need for it on router-to-router links. I believe someone on
> another forum gave the correct answer. Without IGMP, mtrace and mstat
> would not work since those tools use IGMP packets.
> 
> On Mon, Feb 28, 2011 at 4:24 AM, Manu Chao <linux.yahoo at gmail.com> wrote:
>> PIM is used in your Edge and Core network while IGMP is required at the Edge
>> and Access
>> 
>> On Wed, Feb 23, 2011 at 10:24 PM, John Neiberger <jneiberger at gmail.com>
>> wrote:
>>> 
>>> IGMP is enabled automatically when you enable PIM on an interface and
>>> I can't figure out why. I've talked to a few other engineers and no
>>> one can thing of why IGMP would need to be enabled on a
>>> router-to-router connection running PIM. My only thought was that it
>>> was a leftover from PIMv1, which used IGMP type 14 packets, but that's
>>> a total guess.
>>> 
>>> Do any of you happen to know the answer to this piece of trivia?
>>> 
>>> Thanks!
>>> John
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>> 
>> 
> 
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