Unanswered Question
Aug 29th, 2008

I have an application that uses Multicast group address, The application works fine for nodes within the same VLAN, but i am unable to make is communicate with other vlans, I read that Ip Multicast routing has to be enabled, i tried doing that but, feel something else is required, could someone provide a solution to this.

I have this problem too.
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victor_87 Fri, 08/29/2008 - 02:39

I already had a look at that particular document. i have done all the basic searching i need to do already.

I got my hands on lots of documentation on multicasting already and also tried some part of it which didn't work. I dont want to type in commands that i am not sure of on a Cisco 6500 switch having 25 vlans and 4000 users under it.

Even if someone provides a solution i would obviously read all that multicast stuff in a few days.

All i need is that application to work as soon as possible.

i would be thankful if someone could help.

Jon Marshall Fri, 08/29/2008 - 03:09

Which bits did you try. At a very basic level

1) ip multicast-routing

2) int vlan 20

ip pim dense-mode

etc for all vlans you want to route multicast traffic for.

the above should be enough for you to test. You can use sparse mode but then you have to define RP (Rendevous Points).

Also you need to ensure that the ttl in your multicast packets is more than 1 otherwise the packets will only stay local to the vlan they are sourced on.


Joseph W. Doherty Fri, 08/29/2008 - 03:41

If you post a diagram of your topology and what you config looks like, i.e. what you've tried, other might be able to offer some suggestions.


Sorry Jon, didn't see your post when I posted the above.


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