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New Member


I keep getting this P2 warning message 1/Invalid traffice from multicast source on port ?/?. The ?/? are the trunk port between the C4000 and C6509.

I have igmp and cgmp enabled on all Switches and MSFCs as well as the following:

ip pim accept-rp auto-rp

ip pim send-rp-announce Vlan? scope 16

ip pim send-rp-discovery scope 16

Please help.


Cisco Employee

Re: Multicast

The message is just a warning stating that a packet was received by the Catalyst 4000 Switch with a source multicast MAC address. No packet is getting dropped in the switch due to this issue. Source multicast MAC addresses in a packet are not allowed per spec and hence the warning message. The hardware used on Catalyst 4000 provides the warning message not the actually NMP software.

Furthermore, the switch will just flood the frame and not learn the source multicast MAC address. The Catalyst 4000 Family is the only product family to display the message. All Catalyst products will flood these types of frames and not learn the SA. That is why the C6509 is not displaying any message.

Generally, the problem is caused by a software application, bad NIC, or other improperly configured network server, workstation, or applicance. I would investigate the devices connected to port x/y and to try to locate the source of the frame.

New Member

Re: Multicast

Thank you very much.

I have tried searching for the device but it does not seem to exist as all i have to go by is multicast source address 45:00:03:bc:9e:34 on port 2/2. None of the mac addresses on our switch begin with a 45:.

Please how else do I go about looking for this device?


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