Reference Guide

ethernet1/1/8 Disb 128.288 128 200000000 FWD 0 AUTO No
ethernet1/1/9 Disb 128.292 128 200000000 FWD 0 AUTO No
ethernet1/1/10 Disb 128.296 128 200000000 FWD 0 AUTO No
ethernet1/1/11 Disb 128.300 128 200000000 FWD 0 AUTO No
Root assignment
RPVST+ assigns the root bridge according to the lowest bridge ID. Assign one bridge as root bridge and the other as a secondary root
bridge.
• Congure the device as the root or secondary root in CONFIGURATION mode.
spanning-tree vlan vlan-id root {primary | secondary}
• vlan-id — Enter the VLAN ID number (1 to 4094).
• primary — Enter the bridge as primary or root bridge (primary bridge value is 24576).
• secondary — Enter the bridge as secondary or secondary root bridge (secondary bridge value is 28672).
Congure root bridge as primary
OS10(config)# spanning-tree vlan 1 root primary
Verify root bridge information
OS10# show spanning-tree active
Spanning tree enabled protocol rapid-pvst with force-version rstp
VLAN 1
Executing IEEE compatible Spanning Tree Protocol
Root ID Priority 24577, Address 90b1.1cf4.a523
Root Bridge hello time 2, max age 20, forward delay 15
Bridge ID Priority 24577, Address 90b1.1cf4.a523
We are the root of VLAN 1
Configured hello time 2, max age 20, forward delay 15
Interface Designated
Name PortID Prio Cost Sts Cost Bridge ID PortID
----------------------------------------------------------------------
ethernet1/1/5 128.276 128 500 FWD 0 24577 90b1.1cf4.a523 128.276
ethernet1/1/6 128.280 128 500 LRN 0 24577 90b1.1cf4.a523 128.280
Interface
Name Role PortID Prio Cost Sts Cost Link-type Edge
-------------------------------------------------------------
ethernet1/1/5 Desg 128.276 128 500 FWD 0 AUTO No
ethernet1/1/6 Desg 128.280 128 500 LRN 0 AUTO No
Loop guard
This information explains how to congure loop guard on an interface.
• Enable loop guard on a per-port or port-channel interface in INTERFACE mode.
spanning-tree guard {loop | root | none}
• loop — Enables loop guard on an interface.
• root — Enables root on an interface.
• none — Enables the guard mode to none.
• Disable loop guard on a port or port-channel interface in INTERFACE mode.
no spanning-tree guard loop
188
Layer 2