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New Member

multi cast

hi! we r currently running multicast with pim  dense mode enabled in all the 6509 vlan interfaces. i noticed that, when we are doing clonning (multicast) for the PCs using ghost, the traffic spike(for the period of 1 hr) of about 50mbps are seen in almost all the edge sw uplink to the 6509 core sw. Is that normal? Is pim dense mode advisable to be used in a LAN environment?

do i need to turn on RP even if i'm using pim dense mode? it seems that i didn't hv any RP configured in my 6509.

If ii would to use pim sparse mode instead, what would be the configuration/command required?


Hall of Fame Super Bronze

Re: multi cast

PIM Dense Mode will flood the mcast traffic via all PIM enabled interfaces and that's the reason we recommend deploying PIM Sparse mode instead of PIM Dense Mode.

PIM Dense Mode will not make use of a Rendezvous Point. If you intend to use a RP, you must configure PIM Sparse Mode.

You can configure the RP as static RP with the command

ip pim rp-address x.x.x.x

and the interface level command for PIM SM is;

interface fx/x

ip pim sparse




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New Member

Re: multi cast

hi! thanks for the assistance. I got a few questions to check

1) For the RP, can it be one of the vlan interface's IP? what's that the normal practice? What would be the best candidate for the RP? in my case, i only have a pair of 6509 with about 20x 4506 sw. Can i've 2 RPs instead of one?

2) The interface for sparse mode, is it on the vlan interface or physical interface?

3) For the edge switch, do i need to enable multicast with sparse mode command on the physical interface?


Hall of Fame Super Bronze

Re: multi cast

1) Best Practice is to use a Loopback IP address as it always remain up/up.

    Yes, you can have 2 RPs. For this design I recommend using Anycast RP with MSDP.

2) The interface that contains the IP address

3) If the edge switching are routing, you need to enable multicast routing globally as well as enable PIM on all L3 transit interfaces.



New Member

Re: multi cast

hi! so does that mean i only need to enalbe ip multi

cast and dense mode in L3 edge sw and not the L2 edge switch whereby the vlan interfaces are at the core sw?


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