VLAN Translation/Mapping and STP TCNs

[Dennis Olvany]

I configured vlan translation between vlan 2000 on a 6500 and vlan 1 on a 2950. I performed a packet capture to validate the configuration and basic ip connectivity seems good. I did, however, notice topology change notifications (stpFrames.txt attached). I see two frames over and over again: An stp frame from the 2950 and a tcn from the 6500. Looking at the spanning tree details (showSpann.txt attached), I see that the 2950 shows zero received bpdu.

[Matthew Blanshard]

Hey Dennis,

Is vlan 1 allowed across the trunk on the 6500?  Can you put in your configs?

-Matt

[Dennis Olvany]

Here are the configs. Vlan 1 is not allowed on the 6500, but it seems that it should not be necessary. Since ip connectivity works, I would think it works equally for stp.

interface GigabitEthernet9/48
description uplink
no ip address
switchport
switchport trunk encapsulation dot1q
switchport trunk native vlan 50
switchport trunk allowed vlan 2000
switchport mode trunk
switchport nonegotiate
switchport vlan mapping enable
switchport vlan mapping 1 2000
end

interface FastEthernet0/4
description uplink
switchport trunk native vlan 50
switchport trunk allowed vlan 1
switchport mode trunk
switchport nonegotiate
end