1-19 
Configuration example 
# Configure the current switch as the root bridge of MSTI 1 and a secondary root bridge of MSTI 2. 
<Sysname> system-view 
[Sysname] stp instance 1 root primary 
[Sysname] stp instance 2 root secondary 
Configuring the Bridge Priority of the Current Switch 
Root bridges are selected according to the bridge priorities of switches. You can make a specific switch 
be selected as a root bridge by setting a lower bridge priority for the switch. An MSTP-enabled switch 
can have different bridge priorities in different MSTIs. 
Configuration procedure 
Follow these steps to configure the bridge priority of the current switch: 
To do...  Use the command...  Remarks 
Enter system view 
system-view 
— 
Set the bridge priority for the 
current switch 
stp [ instance instance-id ] 
priority priority 
Required 
The default bridge priority of a 
switch is 32,768. 
 
 
z  Once you specify a switch as the root bridge or a secondary root bridge by using the stp root 
primary or stp root secondary command, the bridge priority of the switch cannot be configured 
any more. 
z  During the selection of the root bridge, if multiple switches have the same bridge priority, the one 
with the smallest MAC address becomes the root bridge. 
 
Configuration example 
# Set the bridge priority of the current switch to 4,096 in MSTI 1. 
<Sysname> system-view 
[Sysname] stp instance 1 priority 4096 
Configuring How a Port Recognizes and Sends MSTP Packets 
A port can be configured to recognize and send MSTP packets in the following modes. 
z  Automatic mode. Ports in this mode determine the format of the MSTP packets to be sent 
according to the format of the received packets. 
z  Legacy mode. Ports in this mode recognize/send packets in legacy format. 
z  802.1s mode. Ports in this mode recognize/send packets in dot1s format. 
A port acts as follows according to the format of MSTP packets forwarded by a peer switch or router.  
When a port operates in the automatic mode: