Multicasting on 2960 and 3750

[professorguy]

I have a package called MCHammer which can act as an mcast server or client. The server pushes packets, the client joins then listens, then reports all the packets.

I put the server on a machine on an access port of my 2960 in vlan 99. I put the client on a machine on a different port also in vlan 99.

I fire up the client and it does a JOIN (actually it joins 5 different groups). I have the switch display its igmp snooping groups and it reports NO GROUPS. So the JOIN failed to work. No surprise when I fire up the server, the client hears NOTHING.

The same is true when I try this experiment on a 3750. However, if I define a static mrouter port on the 2960 to be the trunk to the 3750, then the client on the 3750 CAN see the mcasts from the server on the 2960. The switch pushes mcasts out the mrouter port when no clients have registered. So it looks as if the JOINS don't work.

Does MCHammer do something stupid or are the Cisco switches not handling the joins correctly? I'm using BASE 12.2(25)SEE2 (August '06) on both switches.

I know I can fix this by disabling igmp snooping and letting it flood the vlan, but I don't like this solution. I'd rather have multicast actually work. Any suggestions?

 

[vipergg]

Maybe some info here might help.

http://cisco.com/en/US/products/ps6406/products_configuration_guide_chapter09186a0080892a5b.html

 

[professorguy]

Looks like the application in question is using IGMPv3, the JOINS of which do not work on current Cisco switches.

The vendor of the app assures me that it runs AS EXPECTED at 100 other places. However, I think he's lying and it works AS A BROADCAST OVER THE VLAN at those places, and every Cisco switch this app touches must have 'no ip igmp snooping'.

That really shows how the developers work in a vacuum and assume they are the only application running on your network: "Just destroy your network and our app will work great! Oh, there's another app that's now broken? Well, that's not my problem. Bye!"