Use of port numbers in multicast

Unanswered Question
Jun 26th, 2009

If I have two multicast applications that publish a group with the same multicast address but different ports, will two multicast groups be created in the router?

I am trying to conserve multicast address space and this would be one solution, to run multiple applications on different ports.

I have this problem too.
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cchughes Fri, 06/26/2009 - 06:41

We are sharing the multicast address space with others on a very large network that rivals smaller service provider networks. I will need to request a block and my estimation is I'll need 20,000 addresses for my application. Theres no guarantee I'll get that many addresses and will need to have a backup plan.

cchughes Fri, 06/26/2009 - 06:57

All I can tell you is that this is streamed data with many endpoints that could be active at any given moment. NDA keeps me away from specifics.

cisco_lad2004 Fri, 06/26/2009 - 08:21


There few points to be made.

1-Have you considered GLOP addressing.

2-Are you streaming over the internet ?

3-When streaming same Multicast address but different ports this will be delivered to requesting hosts but their applications needs to listen on a given port. this defeats the purpose of BW conservation with Multicast, as you will end up delivering more than one feed all the way to one user who actually only needs one.

The other issue is the routing of Multicast. You will have issues with routing if streaming same Multicast from different servers.




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