Hello Everyone,
I have a simple setup,
Access Switch 2<-- Port Channel 20 ----->Core Switch <---- Port Channel 10 --> Access Switch 1
Access Switch 1 connects to the Core Switch using Port Channel 10.
Access Switch 2 connects to the Core Switch using Port Channel 20.
SVI of the VLAN ( VLAN 20) is configured on the Core Switch and VLAN 20 is allowed on the trunk link connecting both the Access Switches.
VLAN 30 is my management VLAN and I have configured 10.20.30.2 IP address on Access Switch 1 and 10.20.30.3 IP address on Access Switch 2.
IGMP Snooping (and immediate leave) has been enabled on both the switches.
I have enabled igmp querier on both the switches and since 10.20.30.2 is the lowest IP it has been elected as the primary querier.
When I run the command " sh ip igmp querier" on Access Switch 1 it displays that Switch is the querier.
When I run the command " sh ip igmp querier" on Access Switch 2, it displays that 10.20.30.2 is the querier.
Now here comes the problem, I have connected a multicast source (Encoder connected on port gi 1/0/1) and a receiver (Decoder connected on port gi 1/0/2) to Access Switch 2 and both of them are on VLAN 20.
When I issue the command " sh ip igmp snooping groups vlan 20", I can see that the receiver is subscribing to the correct multicast address and port gi 1/0/2 is listed in the output. However, Po20 is also listed in the output.
I am assuming, this is because the group information is being sent out to the querier through port channel 20.
Utilization on the switchport gi 1/0/2 is 800Mbps (which is expected as the multicast source bitrate is set to 800Mbps), but based on the port channel utilization, same 800Mbps is also flowing through the port channel (even though there are no other receivers).
This is just one simple case, now imagine if I have 10 sources and 10 receivers (subscribing to different multicast addresses) then my port channel is flooded with 10x800Mbps of multicast traffic.
How do I prevent this flooding ?
FYI, I am not running PIM as the traffic is on just VLAN 20.
Appreciate any suggestions.
Regards,
Harsha
