Hi,
Just need some help here. A bit confused of what went wrong. I'm just setting up a home lab environment and I have observed this weird behaviour.
For some reason both of my L3 switches (3560) have elected themselves to be the root bridge for VLAN 101, I have configured SW1 to the the root bridge for VLAN 101 and SW2 the root bridge for VLAN 102. I have an additional 2 L2 switches in my lab network.
This is a really basic configuration and I haven't done any VLAN prunning and all VLAN's are allowed through the trunks. All switches are within the same VTP domain and the mode is set to transparent.
I also came across a similar thread however the solutions/bug is for the Cisco 3550, and I'm running a 3560 switch.
https://supportforums.cisco.com/discussion/9556911/spanning-tree-multiple-roots
Any assistance would be greatly appreciated.
SW1 output:
VLAN0101
Spanning tree enabled protocol rstp
Root ID Priority 28773
Address 0014.a8e3.1600
This bridge is the root
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
Bridge ID Priority 28773 (priority 28672 sys-id-ext 101)
Address 0014.a8e3.1600
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
Aging Time 300
Interface Role Sts Cost Prio.Nbr Type
---------------- ---- --- --------- -------- --------------------------------
Fa0/23 Desg FWD 19 128.25 P2p
Fa0/24 Desg FWD 19 128.26 P2p
SW2 output:
VLAN0101
Spanning tree enabled protocol rstp
Root ID Priority 24677
Address 0012.d9a4.bc80
This bridge is the root
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
Bridge ID Priority 24677 (priority 24576 sys-id-ext 101)
Address 0012.d9a4.bc80
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
Aging Time 300
Interface Role Sts Cost Prio.Nbr Type
---------------- ---- --- --------- -------- --------------------------------
Fa0/23 Desg FWD 19 128.25 P2p
Fa0/24 Desg FWD 19 128.26 P2p
