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New Member

Multicast problems on catalyst 2950 v12.1(9)EA1


I have the following scenario:

2 Firewall1in load-balance - FW1 and FW2

2 catalyst 2950 48 ports with 12.1(9) EA1 version - SW1 and SW2

FW1 is plugged to SW1 by trunk on interface G0/1, FW2 is plugged to SW2 by trunk on interface G0/1 and between switches there is a trunk fyber link on interface G0/2 on each switch.

The ip igmp snooping feature is disabled and multicast mac-addresses are statically defined on interfaces G0/1 and G0/2 on each switch.

It seems to me that if i have a PC connected to SW1, packets arrive to FW1 with right tagging on correct VLAN and to FW2 without tag.

Hence, FW2 will discard the packets and connectivity will be lost.

With 2 FW and just one switch everything works well. This scennario drives me to point to a multicast problem or a bug not reported on these


Do you advice any workaround?

Maybe an upgrade to new version 12.1(12c)EA1...


Re: Multicast problems on catalyst 2950 v12.1(9)EA1

An upgrade would be a good idea if you feel the problem is possibly due to a bug.

However the following doc on Multicast Troubleshooting might help you rule out any possible problems.

New Member

Re: Multicast problems on catalyst 2950 v12.1(9)EA1


You expect the multicast will be send bi-directional over a single link. This will introduce a classic bridge loop and is not permitted, even this is recommended by some FW suppliers!

Regard’s Andy

New Member

Re: Multicast problems on catalyst 2950 v12.1(9)EA1

I have the same scenario working with catalyst 3550 L3 with just layer 2 !!

Beside this all gigabit ports of the catalyst 2950 are in forwarding state so, i think this is not a loop problem and i didn't detect any blocked state. The Firewalls should prevent eventual loops!!!!

Thanks Nuno

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