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New Member

Multicast traffic flooding


We are using Network Load Balancing on some Windows 2003 servers which is configured as IGMP multicast.

The servers are connected to a 3550 SMI switch which is connected to a HP4108.

Before I configured either of these switches I connected a packet sniffer and saw the multicast traffic appearing on all ports on both switches.

I configured the HP switch as a Multicast querier and now on the 3550 I see the multicast mac addresses logged against the server ports. The 3550 also detects the muticast router as you can see:

prod-3550#sh mac-address-table mult

Vlan Mac Address Type Ports

---- ----------- ---- -----

1 0100.5e7f.4601 IGMP Fa0/10, Fa0/12, Gi0/1

1 0100.5e7f.4602 IGMP Fa0/9, Fa0/11, Gi0/1


prod-3550#sh ip igmp snoo mrouter

Vlan ports

---- -----

1 Gi0/1(dynamic)

The 3550 is still spamming the multicast traffic to all ports whereas the HP switch is only replicating thisto ports that are part of the multicast group.

Can anyone tell me why the 3550 is doing this or what else I need to check?

Thanks in advance.

Hall of Fame Super Silver

Re: Multicast traffic flooding


You do not tell us much about how the 3550 is configured. From your description of the problem I am going to assume that you do not have IGMP snooping configured. This link will show you how to configure IGMP on the 3550:

If my assumption is not correct and you do have IGMP snooping configured, then you will need to tell us more about how the 3550 is configured so we can determine why it is propagating multicast to all ports.



New Member

Re: Multicast traffic flooding

The 3550 is configured with the following:

ip multicast-routing

interface Vlan104

description Production

ip address 10.x.x.x

ip pim dense-mode