PIM sparse mode and muliple sources for a group

Unanswered Question
Dec 1st, 2007

I have two sources multicasting for the same group. Network connectivity is as follows:

source s1 (on vlan X) and s2 (on vlan Y)------multicast router------Receiver (on vlan Z)

Receiver is using IGMP V2 to join the group. Given the fact that Multicast Router can see both sources for the same group, how is Multicasting router supposed to select which (S,G) channel should be used for forwarding multicast to receiver?

I have this problem too.
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wochanda Sat, 12/01/2007 - 13:51

It doesn't. If you want to be able to select both your stream and your source, you need to do PIM-SSM and IGMPv3.

With PIM-SM and IGMPv2, the receiver will get both streams.

abidkhanusa Sat, 12/01/2007 - 14:01

Well, that's interesting. In my case, router is choosing only one stream. For the other stream, "show ip mroute" output indicates Incoming interface as Null. "show ip mroute active" only shows the first (active) stream.

Harold Ritter Sun, 12/02/2007 - 11:50

Vlan Z should definitely receive both streams. You can change that by using IGMPv2 for the receiver on vlan Z or use IGMPv2 to v3 mapping on the multicast routing.



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