1-18Configuration example# Configure the MST region name to be “info”, the MSTP revision level to be 1, and VLAN 2 throughVLAN 10 to be mapped to MSTI 1 and VLAN 20 through VLAN 30 to MSTI 2. system-view[Sysname] stp region-configuration[Sysname-mst-region] region-name info[Sysname-mst-region] instance 1 vlan 2 to 10[Sysname-mst-region] instance 2 vlan 20 to 30[Sysname-mst-region] revision-level 1[Sysname-mst-region] active region-configurationSpecifying the Root Bridge or a Secondary Root BridgeMSTP can determine the root bridge of a spanning tree through MSTP calculation. Alternatively, youcan specify the current device as the root bridge using the commands provided by the system.Specifying the current device as the root bridge of a specific spanning treeFollow these steps to specify the current device as the root bridge of a specific spanning tree:To do... Use the command... RemarksEnter system view system-view —Specify the current device asthe root bridge of a specificspanning treestp [ instance instance-id ]root primaryRequiredBy default, a device does notfunction as the root bridge.Specifying the current device as a secondary root bridge of a specific spanning treeFollow these steps to specify the current device as a secondary root bridge of a specific spanning tree:To do... Use the command... RemarksEnter system view system-view —Specify the current device as asecondary root bridge of aspecific spanning treestp [ instance instance-id ]root secondaryRequiredBy default, a device does notfunction as a secondary rootbridge.Note that:z After specifying the current device as the root bridge or a secondary root bridge, you cannotchange the priority of the device.z You can configure the current device as the root bridge or a secondary root bridge of an MSTI,which is specified by instance instance-id in the command. If you set instance-id to 0, the currentdevice will be the root bridge or a secondary root bridge of the CIST.z The current device has independent roles in different MSTIs. It can act as the root bridge or asecondary root bridge of one instance while it can also act as the root bridge or a secondary rootbridge of another MSTI. However, the same device cannot be the root bridge and a secondary rootbridge in the same MSTI at the same time.
