Switch 7700 Command reference Guide, v2.0

MSTP Configuration Commands 327
■ Use the undo stp instance port priority command to restore the default
priority of the port on the specified STI.
You may specify the instance-id parameter as 0 to configure CIST priority of the
port. The port priority has effect on the port role selection. A port can be
configured with different priorities on different MSTIs. Thus the traffic from
different VLANs can run over different physical links, thereby implementing the
VLAN-based load-balancing. MSTP will recalculate the port role and transit its
state, upon the port priority changes.
Related command: stp interface instance port priority.
Example
Set the priority of Ethernet5/0/3 on STI 2 to 16.
[SW7700-Ethernet5/0/3]stp instance 2 port priority 16
stp instance root
primary
Syntax
stp instance instance-id root primary [ bridge-diameter bridgenum [
hello-time centi-senconds ] ]
undo stp instance instance-id root
View
System view
Parameter
instance instance-id: Specifies the spanning tree instance ID, ranging from 0
to 16. Specify it as 0 to configure the root bridge of CIST.
root primary: Configure the current switch as the primary root of the
designated STI.
bridge-diameter bridgenum: Specify the network diameter of the spanning
tree, ranging from 2 to 7.
hello-time centi-seconds: Specifies the Hello Time of the spanning tree,
ranging from 100 to 1000 and measured in centiseconds.
Description
■ Use the stp instance root primary command to configure the current
switch as the primary root of the designated STI.
■ Use the undo stp instance root command to cancel the current switch for
the primary root of the designated STI.
By default, the switch does not server as a root bridge.
You can configure a root bridge for every STI without concerning the switch
priority. When configuring the root bridge, you may also specify the network
diameter of the designated switching network, so that the switch will calculate
and get three time parameter values (Hello time, Forward Delay and Max Age).
The Hello time got in this way may not be as good as expected. You can specify
the hello-time
centi-seconds parameter to overwrite it. Normally, you are