Concept Guide

no ip address
switchport
spanning-tree rstp edge-port
shutdown
Dell(conf-if-te-2/0)#
Inuencing RSTP Root Selection
RSTP determines the root bridge, but you can assign one bridge a lower priority to increase the likelihood that it is selected as the root
bridge.
To change the bridge priority, use the following command.
• Assign a number as the bridge priority or designate it as the primary or secondary root.
PROTOCOL SPANNING TREE RSTP mode
bridge-priority priority-value
– priority-value The range is from 0 to 65535. The lower the number assigned, the more likely this bridge becomes the root
bridge.
The default is 32768. Entries must be multiples of 4096.
Example of the bridge-priority Command
A console message appears when a new root bridge has been assigned. The following example example shows the console message after
the bridge-priority command is used to make R2 the root bridge (shown in bold).
Dell(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
SNMP Traps for Root Elections and Topology
Changes
To enable SNMP traps for RSTP, MSTP, and PVST+ collectively, use the following command.
Enable SNMP traps for RSTP, MSTP, and PVST+ collectively.
snmp-server enable traps xstp
Conguring Fast Hellos for Link State Detection
To achieve sub-second link-down detection so that convergence is triggered faster, use RSTP fast hellos.
The standard RSTP link-state detection mechanism does not oer the same low link-state detection speed.
RSTP fast hellos decrease the hello interval to the order of milliseconds and all timers derived from the hello timer are adjusted accordingly.
This feature does not inter-operate with other vendors, and is available only for RSTP.
• Congure a hello time on the order of milliseconds.
PROTOCOL RSTP mode
hello-time milli-second interval
The range is from 50 to 950 milliseconds.
Example of Verifying Hello-Time Interval
Dell(conf-rstp)#do show spanning-tree rstp brief
Executing IEEE compatible Spanning Tree Protocol
Root ID Priority 0, Address 0001.e811.2233
Root Bridge hello time 50 ms, max age 20, forward delay 15
Bridge ID Priority 0, Address 0001.e811.2233
716
Rapid Spanning Tree Protocol (RSTP)