All things related to multicast

[Gordon Rogier <>]

I am seeing an issue with the 'bursty' frequency of the sdr announcers and
it's relationship to setting up and maintaining mroute state.  It appears
to me that the mroute state is being torn down by a built in Cisco 
IOS timeout of 3minutes; this coupled with that many sdr announcers are
announcing with a greater than 3minutes separation is causing
cascaded/edge sites to miss many sdr announcements.

In essence the mroute state setup at the edge sparse interconnects as
a result of msdp SA information about the sdr group.   If the
sdr group does not sent out a packet to the sdr group within the 
3minute mroute tear down period, then the mroute state begins
tearing down between the sdr announcer and the edge networks.
Thus backholing many sdr announcments from reaching these edge
network.

Now this is aggravated if consider that effectively sdr
announcers are 'bursty' (where the burst is quite small).  This
bursty nature of sdr sources effectively prevents the edges from 
seeing the sdr list by the timing of sdr -> 
rp@source
 -> msdp ->
rp@edge
 -> 
rp@edge
 setup mcast spt joins -> mroute state -> mroute state
timeout and tear down -> back to beginning sdr announcement & repeat
cycle.

Is anyone else seeing this??

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Gordon Rogier                        

            
Network Engineer                     785-864-0381wk 785-550-4468 cell
Great Plains Network                 785-864-9330 FAX