Trunking on an interface

Unanswered Question
Feb 23rd, 2009

Good day!

I have recently discovered a peculiar thing about enabling/disabling trunking on a switch interface.

In a topology for inter-Router VLAN trunking, after disabling trunking on an interface connectivity between the devices on two different VLANs remains.

After about 5-7 minutes connectivity fails as it basically should be after disabling trunking mode. However for the first 5-7 minutes, I am able to ping and reach the machine on the other VLAN.

So my question: is there any timeout for trunking on an interface in the cisco switches or it is cashed somewhere/somehow?

I couldn't find the answer for that.

Thank you very much in advance!


I have this problem too.
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milan.kulik Mon, 02/23/2009 - 02:16


looks to me like the switch forwarding address table keeping the VLAN/MAC pair for the destination devices.

After forwarding table age-out (5 minutes by default), you are losing the connectivity.

You should be able to check by issuing

sh mac-address-table





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