I am just trying to understand what is going on here... In attachment you find a simple scenario... The vlans 5 to 10 are the DMZ Vlans which are the sub-interfaces in ASA Firewall. The point that I don't understand is that why for all these Vlans, switch1 and switch DMZ are both root bridge! I understand that a device such as ASA which is not able to manage the BPDU filters them, but in this scenario I have a trunk between the switch1 and DMZ.
Can somebody please explain me why both Switch1 and DMZ are root bridges for these Vlans?
Here is some show command outputs:
DMZ#sh spanning-tree vlan 5
VLAN0005
Spanning tree enabled protocol ieee
Root ID Priority 32773
Address ec30.9173.5100
This bridge is the root
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
Bridge ID Priority 32773 (priority 32768 sys-id-ext 5)
Address ec30.9173.5100
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
Aging Time 300 sec
Interface Role Sts Cost Prio.Nbr Type
------------------- ---- --- --------- -------- --------------------------------
Gi0/1 Desg FWD 4 128.1 P2p
Gi0/22 Desg FWD 4 128.22 P2p
Switch1#sh spanning-tree vlan 5
VLAN0005
Spanning tree enabled protocol rstp
Root ID Priority 32773
Address 5475.d0d0.3a80
This bridge is the root
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
Bridge ID Priority 32773 (priority 32768 sys-id-ext 5)
Address 5475.d0d0.3a80
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
Aging Time 300 sec
Interface Role Sts Cost Prio.Nbr Type
------------------- ---- --- --------- -------- --------------------------------
Gi2/0/20 Desg FWD 4 128.74 P2p
