FTOS Configuration Guide for the C-Series - Force10 Networks

Influence RSTP Root Selection
The Rapid Spanning Tree Protocol determines the root bridge, but you can assign one bridge a lower
priority to increase the likelihood that it will be selected as the root bridge.
To change the bridge priority, use the following command:
Task Command Syntax Command Mode
Assign a number as the bridge priority or designate it as
the primary or secondary root.
priority-value range: 0 to 65535. The lower the number
assigned, the more likely this bridge will become the
root bridge. The default is 32768. Entries must be
multiples of 4096.
A console message appears when a new root bridge has been assigned. Figure 299 shows the console
message after the bridge-priorty command is used to make R2 the root bridge.
Figure 299 bridge-priority Command Example
bridge-priority priority-value PROTOCOL
SPANNING TREE
RSTP
Force10(conf-rstp)#bridge-priority 4096
04:27:59: %RPM0-P:RP2 %SPANMGR-5-STP_ROOT_CHANGE: RSTP root changed. My Bridge ID:
4096:0001.e80b.88bd Old Root: 32768:0001.e801.cbb4 New Root: 4096:0001.e80b.88bd
Old root bridge ID
New root bridge ID
SNMP Traps for Root Elections and Topology Changes
Enable SNMP traps for RSTP, MSTP, and PVST+ collectively using the command snmp-server enable
traps xstp.
FTOS Configuration Guide, version 7.7.1.0 417