Help with root bridge

[drewdown]

Have a 3750 (core) doing Layer 3 routing, roughly 10 vlans, 9 of which show the CORE 3750 switch as their root bridge. But one vlan does not, it is showing an old 2900 as its root bridge.

Even after I put them in a root bridge group and set the priority to a low number, that paticular vlan still elects the 2900 its root bridge.

IE all vlans show gig1/0/1 has their root port, but vlan2 shows fas1/0/40 as its root port.

Why is that? And how can I make it so gig1/0/1 is its root port? spanning-tree port-priority?

I am at a loss.

TY

 

[vipergg]

Use the command on the 3750 "spanning-tree vlan 2 root primary " and see if that changes it .

 

[drewdown]

viperegg, that's the correct command. I figured it out after I posted this thread. But I found that Cisco's documentation is poor regarding this. Eveything I read on Cisco's site stated I need to create a Bridge group and change the groups priority. Nowhere did I find that command until I started doing "?" on any spanning-tree command I could find on the switch.

Thanks man.