3Com 10014298 manual By default, the switch priority is, Configure the Mstp Running Mode

Configuring MSTP 193

provides two operation modes, STP-compatible mode and MSTP mode. In STP-compatible mode, the switch sends STP packets by every port and serves as a region itself. In MSTP mode, the switch ports send MSTP or STP packets (when connected to the STP switch) and the switch provides the multiple spanning tree function.

You can use the following command to configure MSTP running mode. MSTP can intercommunicate with STP. If there is a STP switch in the switching network, you can use the command to configure the current MSTP to run in STP-compatible mode, otherwise, configure it to run in MSTP mode.

Perform the following configuration in system view.

Table 193 Configure the MSTP Running Mode

Operation	Command
Configure MSTP to run in STP-compatible	stp mode stp
mode
Configure MSTP to run in RSTP mode	stp mode rstp
Configure MSTP to run in MSTP mode.	stp mode mstp
Restore the default MSTP running mode	undo stp mode

Generally, if there is a STP switch on the switching network, the port connected to it will automatically transit from MSTP mode to STP-compatible mode. The port cannot automatically transition itself back to MSTP mode after the STP switch is removed. In this case, you can perform the mcheck operation to transit the port to MSTP mode by force.

By default, MSTP runs in MSTP mode.

Configuring the Bridge Whether a switch can be elected as the spanning tree root depends on its bridge Priority for a Switch priority. The switch configured with a lower bridge priority is more likely to

become the root. An MSTP switch can have different priorities in different STIs.

You can use the following command to configure the bridge priorities of the designated switch in different STIs.

Perform the following configuration in system view.

Table 194 Configure the Priority for a Switch

Operation	Command
Configure the priority of the designated	stp instance instance-idpriority
switch.	priority
Restore the default priority of the designated	undo stp instance instance-id
switch.	priority

When configuring the switch priority with the instance instance-idparameter, with a value of 0, you are configuring the CIST priority of the switch.

In the process of spanning tree root election of two or more switches, with the lowest priorities, the one has a smaller MAC address will be elected as the root.

By default, the switch priority is 32768.