All things related to multicast

["Marshall Eubanks" <>]

>>[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.

Yes, this is how it works - it's because 
you have to find the RP's before you can
send multicasts to the RP's. DM floods things around.

IMHO it's better to use BSR. (Of course, YMMV.)

Marshall

>>
>>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!
>>
>
>There was a recent problem at an ISP I know of where they
>upgraded their IOS and auto-rp messages started leaking through
>filters (or started being paid attention to) - I have also
>heard of similar problems with BSR messages after upgrades.
>
>Did you recently do an IOS change ?
>
>Marshall Eubanks
>Multicast Technologies.
>>
>
>Marshall Eubanks
>
>
>
>

Marshall Eubanks