SG300-28P Multicast (IGMP) and IGMP routing..

Question

A brief background on the setup:
I recently switched out my switch.  It was a Cisco 3750 10/100 switch and I wanted to upgrade to Gig.  The cost of a Gig+POE 3750 is too much to bite so I opted for the SG300.  My router is a Cisco 891.  Here is the setup:
Cisco 891:
two SVI's: vlan1 and vlan 100
Vlan1 = 10.0.1.1/24
Vlan100 = 10.0.100.2/24
Connected to SG300 via Fa0
DHCP Server for vlan1+vlan100
Cisco SG300-28P:
two SVI's: vlan 1 and vlan 100
vlan 1 = 10.0.1.21/24
vlan 100 = 10.0.100.1/24
Connected to 891 on via Gi18
The connection between 891 and SG300 = trunk, vlan1-u, vlan100-t
The problem:
With the 891+3750, I was able to add "ip pim sparse-dense-mode" on all the SVI's and hosts could join any multicast group, irregardless of which vlan the host was a member of.
Now I've changed switches, and I dont get the same love.  I have the PIM statement on both SVI's on the 891, but Im unsure of what I need to configure on the SG300.  I have enabled "Bridge multicast filtering" + "IGMP snooping".  What can I do to get similar functionality using the SG300 + 891?  I assume this is my lack of understanding IGMP in general, but was able to get away with it using the PIM statements on the 891+3750 stack.
Jeff

Answer 1

You should be able to filter unregisted multicast on every port.
To be able to pass multicast over subnets two things must be certain, the node/device is able to send and receive multicast packets but also register the multicast address being listened to by the node so the local and remote routers can route the multicast packets.
When the switch learns a multicast address through IGMP snooping, this is a registered multicast. The switch will only forward multicast to ports that are registered to the multicast group. Where unregistered multicast comes in, is the multicast that is not statically defined or learned through IGMP which in turn will be forwarded to all ports of the vlan.