462 CHAPTER 23: MSTP C ONFIGURATION■ Alternatively, you can also specify the current device as the root bridge bysetting by priority of the device to 0. For the device priority configuration, referto “Configuring the Priority of the Current Device” on page 462.Configuration example# Specify the current device as the root bridge of MST instance 1 and a secondaryroot bridge of MST instance 2. system-view[Sysname] stp instance 1 root primary[Sysname] stp instance 2 root secondaryConfiguring the WorkMode of MSTP DeviceMSTP and RSTP can recognize each other’s protocol packets, so they are mutuallycompatible. However, STP is unable to recognize MSTP packets. For hybridnetworking with legacy STP devices and full interoperability with RSTP-compliantdevices, MSTP supports three work modes: STP-compatible mode, RSTP mode,and MSTP mode.■ In STP-compatible mode, all ports of the device send out STP BPDUs,■ In RSTP mode, all ports of the device send out RSTP BPDUs. If the devicedetects that it is connected with a legacy STP device, the port connecting withthe legacy STP device will automatically migrate to STP-compatible mode.■ In MSTP mode, all ports of the device send out MSTP BPDUs. If the devicedetects that it is connected with a legacy STP device, the port connecting withthe legacy STP device will automatically migrate to STP-compatible mode.Configuration procedureFollow these steps to configure the MSTP work mode:Configuration example# Configure MSTP to work in STP-compatible mode. system-view[Sysname] stp mode stpConfiguring the Priorityof the Current DeviceThe priority of a device determines whether it can be elected as the root bridge ofa spanning tree. A lower value indicates a higher priority. By setting the priority ofa device to a low value, you can specify the device as the root bridge of spanningtree. An MSTP-compliant device can have different priorities in different MSTinstances.Configuration procedureFollow these steps to configure the priority of the current device:To do... Use the command... RemarksEnter system view system-view -Configure the work mode ofMSTPstp mode { stp | rstp | mstp } OptionalMSTP mode by defaultTo do... Use the command... RemarksEnter system view system-view -
