Example of Assigning and Verifying the Root Bridge PriorityBy default, the simple configuration shown previously yields the same forwarding path for both MSTIs. The following example shows howR3 is assigned bridge priority 0 for MSTI 2, which elects a different root bridge than MSTI 2.To view the bridge priority, use the show config command from PROTOCOL MSTP mode.R3(conf-mstp)#msti 2 bridge-priority 01d2h51m: %RPM0-P:RP2 %SPANMGR-5-STP_ROOT_CHANGE: MSTP root changed for instance 2. MyBridge ID: 0:0001.e809.c24a Old Root: 32768:0001.e806.953e New Root: 0:0001.e809.c24aR3(conf-mstp)#show config!protocol spanning-tree mstpno disableMSTI 1 VLAN 100MSTI 2 VLAN 200,300MSTI 2 bridge-priority 0Interoperate with Non-Dell BridgesDell Networking OS supports only one MSTP region.A region is a combination of three unique qualities:• Name is a mnemonic string you assign to the region. The default region name is null.• Revision is a 2-byte number. The default revision number OS is 0.• VLAN-to-instance mapping is the placement of a VLAN in an MSTI.For a bridge to be in the same MSTP region as another, all three of these qualities must match exactly. The default values for the name andrevision number must match on all Dell Networking OS devices. If there are non-Dell devices that participate in MSTP, ensure these valuesmatch on all devices.NOTE: Some non-Dell devices may implement a non-null default region name. SFTOS, for example, uses the Bridge ID, whileothers may use a MAC address.Changing the Region Name or RevisionTo change the region name or revision, use the following commands.• Change the region name.PROTOCOL MSTP modename name• Change the region revision number.PROTOCOL MSTP moderevision numberExample of the name CommandTo view the current region name and revision, use the show spanning-tree mst configuration command from EXEC Privilegemode.Dell(conf-mstp)#name my-mstp-regionDell(conf-mstp)#exitDell(conf)#do show spanning-tree mst configMST region name: my-mstp-regionRevision: 0MSTI VID1 1002 200-300Multiple Spanning Tree Protocol (MSTP) 561
