IGMP related in multicasting

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Jul 20th, 2009
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i have query related IGMP in multicasting. does i need to enable IGMP on my router interface connected to LAN???? or it would be activated when i run ip pim sparse command on LAN interface?

it will work if i only apply ip pim sparse command on my LAN interface??? i dont need to enable IGMP command when there are already pim command available???

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Edison Ortiz Mon, 07/20/2009 - 05:42
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A router shouldn't be doing IGMP joins unless it is for troubleshooting purposes.

To route multicast traffic, you need PIM and you can use either sparse, sparse-dense or dense.

Sparse is the recommend PIM method but be aware that you must configure a RP.



Pavel Bykov Mon, 07/20/2009 - 06:10
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First, clarifications:

IGMP is the protocol used for communication between receiver host and router

PIM is the protocol used between routers

Sender does not need any intelligence and does not have to cumminicate at all - just send the packet

To answer your questions:

1. Yes, you need to enable IGMP for the receiver segments

2. IGMP is activated automatically when you enable PIM on the interface. You cannot enable IGMP without PIM

3. YES

4. No

chiragvyas_50 Tue, 07/21/2009 - 05:26
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Thanx a ton you.......

you are telling that IGMP will automatically be activated when i enable PIM on the interface. right??

i got that point but one more query is that PIM protocol is used b/w routers, right?? when i see the pim enable router interface connected to other router, there is IGMP also running.

is there any special purpose for IGMP while communication is going on b/w two routers?? why IGMP also running with PIM b/w routers??


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