Media for Catalyst 3750 how to get multicast packets to go only to group member ports?

Catalyst 3750 how to get multicast packets to go only to group member ports?

Hi, I'm thinking this is something simple, but I'm not very familiar with the configuration of Cisco switches / routers.

Can somebody tell me how I can get my Catalyst 3750 switch to not broadcast multicast data to all ports? I have a really simple switch setup. All ports are on the same VLAN and are connected to devices with IP's on the same subnet. There is a router attached to one port, but no multicast data needs to flow through it.

I spent a couple hours digging around today trying to figure this out but without any luck. I verified IGMP snooping is enabled on the Catalyst and on my VLAN. Since all my ports are connected directly to PC type devices, I turned on support for IGMP v2 immediate leave requests. From what I see when I type show ip igmp groups, I can see the switch is aware of what ports it has gotten IGMP group join requests from. The problem is that it doesn't seem to use that information to intelligently distribute multicast data. I'm seeing the data on ports that are not listed as being part of the group.

I found one post where a guy said he needed to attach a router to the switch that had multicast routing enabled in order for the multicast data not to broadcast. Another post said if all the multicast is just on one VLAN then no router is needed. I tried enabling multicast routing on the router I have, but it didn't seem to help, but I may not have set it up correctly.

Also one other thing I notice with this switch is the interfaces can take up to 10 seconds or so to become active after being plugged in. What would this be caused from? I'm guessing its trying to detect things out about the link that don't matter in my setup.

Thanks in advance.

-Tom