All things related to multicast

[Alan Crosswell <>]

[I finally fixed my nlanr/AG beacon and went to test it and discovered
multicast had broken on my subnet:-].

So this time, we have a router that has one of it's two redundant
links to the rest of the campus routers down (dual star topology;
subnets 1 and 2).  All campus routers with the exception of the I2
router (and RP) are on subnets 1 and 2.  The I2 router is only on
subnet 1.  The router that has a link down has subnet 1 down.  Unicast
routing works just fine via subnet 2 where one of the other half-dozen
routers moves the subject router's traffic from subnet 2 back to
subnet 1 for access to the I2 router/RP.

We are using auto-rp.  I do a "show ip pim rp" successively and see
the RP present for a very small number of groups, and then a second
later no RPs, and then a while later RPs but again only for a small
number of groups.  I have some debug output that I'll send to TAC
RSN....  

The workaround was to manually configure the I2 router as the RP (ip
pim rp-address 128.59.0.6) and multicast connectivity is back.

So I guess it's something funky going on with the way auto-rp works which
I thought was PIM-DM which is why the router interfaces have to be configured
in sparse-dense mode.

IOS version is: 

IOS (tm) c6sup2_rp Software (c6sup2_rp-JSV-M), Experimental Version 
12.1(20010728:011232) [shj-V121_8A_E 109]

It's stable, really!  It was built a whole week ago:-)

/a

PS: This time when Phil at Cornell replies saying how he solved it I
    will pay attention and not just save the mail for 6 months!