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Limitations on multicast helper map command

Level 1
Level 1

Hi All,

I have 3 sites A, B, C. All three are broadcast networks. Server in Site A sends broadcast traffic and R1 router in site A will convert this broadcast to multicast using "ip multicast helper-map". My destinations are in B and C sites. Does IP multicast helper map command support more than one destinations or are there any limitations. Also do we need to configure RP when we use ip multicast helper-map command. 

Please advice.



2 Replies 2

Cisco Employee
Cisco Employee

Hey Sudhakar,

With the multicast helper map you will be converting the ingress broadcast packet to a multicast packet. Therefore you should be able to send this to multiple sites, If you have both site B & C join the multicast group that you convert the Broadcast packet to, the data should flow to them. On the egress routers on sites B & C you can then convert the ingress multicast feed back into a dedicated LAN broadcast.

As for RP's, this depends. If you are running PIM-SPARSE mode then you will need an RP, if running DENSE then you will not. You will require PIM to be enabled on the links between the source & destinations.

In reagrds to the PIM design, without a view of the connectivity between the three sites, its hard to say how to approach this. But in short, yes it should work & you will need multicast enabled along the transit links & devices. 



Thanks for the info, Sam!

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