How to configure Multicast on a 6500?

Dec 06, 2005 2 Replies
How to configure Multicast on a 6500? open original image

We have a single 6509 router at our campus, with mostly 3524's and 3548's at the edge, all connected through a gigabit backbone. The 6505 has a split configuration (CatOS in the switch engine, IOS on the router blade). I want to configure the router/switch to allow multicast traffic to pass through the router properly, at least for some subnets. I wrote a simple pair of programs, one that joins a multicast group and waits for traffic, and another that sends out a packet to the same multicast group. If I run the two programs on the same subnet, the reciever programs gets the multicast packet sent out by the sender. However, if the receiver and sender are on different subnets, the multicast packets for the group never arrive. An ethernet trace confirms it.



I've done numerous Google searches trying to find the correct way to set up multicast for our environment, but nothing that I try works. I've tried both dense and sparse mode but there's obviously more required. Any suggestions on what I should be doing would be greatly appreciated.


You also need to perform configuration on the switch (CATOS), see:

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How exactly did you configure your routers?

It can be as simple as:

ip multicast-routing ! int vlan 101 ip pim dense-mode

But there are a lot of little issues that can hurt you if you don't do this right. On the other hand, if you have a small network, it can be pretty simple to configure.

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