[c-nsp] Multicast state behavior differences between 7600 and ASR9k

[John Neiberger]

That doesn't seem to do what I was hoping. In IOS, we have S,G entries
for all multicast sources connected to a router whether or not there
is anything joining the stream. This doesn't seem to happen in IOS XR.
I'm beginning to think that this behavior was changed on purpose,
although I can't think of any good reason why yet. Another Cisco
engineer suggested turning on NetFlow and then using NetFlow commands
to get the same information. That's a good idea, but why would Cisco
take away such a useful troubleshooting tool in the first place?

Besides, it's my opinion that if there is a multicast sender on a
port, then multicast state exists and we should be able to use a
simple multicast show command to view the state.

Thanks,
John

On Mon, Feb 28, 2011 at 4:20 AM, Manu Chao <linux.yahoo at gmail.com> wrote:
> Just add the * option in your show mrib route ios-xr command to see the
> shared tree entries
>
> You may see a difference between show mrib route * and show mfib route *
> table.
>
> R/
>
> On Fri, Feb 25, 2011 at 12:40 AM, John Neiberger <jneiberger at gmail.com>
> wrote:
>>
>> We're seeing a little weirdness that we're having trouble deciphering.
>> We have a multicast source connected to a 7600 and we're using SSM. If
>> the source starts sending, an mroute entry is created in the mroute
>> table immediately, whether or not anything is joining the group. So,
>> prior to anything actually joining the group, we can see which groups
>> that source is sending to simply by doing a "show ip mroute".
>>
>> The behavior is different on the ASR9k. On that platform, there are no
>> entries in the mrib when the source is sending. The mrib entries are
>> not created until something joins the group. Once the receiver leaves
>> the group, the mrib entries disappear. This is not expected behavior
>> and we've had a few people from Cisco say that multicast state should
>> be created if the source is sending, whether or not anything is
>> joining.
>>
>> Do any of you have any idea why this behavior is different on the ASR?
>>
>> Thanks!
>> John
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