peering with Black Diamond Switch , How to avoid becoming STP root

[yongaik]

we had Catalyst 3550 link to Black Diamond Switch which STP priority are set to 0. By setting cat3550 vlan STP priority to 32768, the cat3550 still become the vlan STP root bridge. Any way to prevent cat3550 from becoming the root here??

[bbranch]

On the Black Diamond you need to create the STP domain and a tag that matches the VLAN to which the STP domain is being associated. STP should then be enabled and the mode of the STP ports selected.

i.e.

Create stpd domain1

Co stpd domain1 tag 10

Co vlan vlan10 add port 1:1 untagged stpd domain1 dot1d

[sbhadrav@cisco.com]

Use the following command in your switch global configuration mode:

spanning-tree vlan 1-3550 priority 32768

The root is the switch with the lowest priority setting, and the value indicated here (32768) is the highest configurable value. All other switches should therefore be more preferred.