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Webcast-Catalyst9k
New Member

PIM sparse mode and muliple sources for a group

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?

4 REPLIES
Silver

Re: PIM sparse mode and muliple sources for a group

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.

New Member

Re: PIM sparse mode and muliple sources for a group

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.

New Member

Re: PIM sparse mode and muliple sources for a group

Hi,

Which entry has the iif as null?(s,G) or (*,G).

-Nambi

Cisco Employee

Re: PIM sparse mode and muliple sources for a group

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.

Regards,

Harold Ritter
Sr. Technical Leader
CCIE 4168 (R&S, SP)
harold@cisco.com
México móvil: +52 1 55 8312 4915
Cisco México
Paseo de la Reforma 222
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Cuauhtémoc, Juárez
Ciudad de México, 06600
México
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