Command
Spanning-Tree Backbonefast
Use
This command will prevent a switch that has lost its link to the root switch from becoming root when the root is still running. If switches receive an inferior BPDU from a switch, backbonefast will send them the proper information for reaching the root.
Syntax
Switch(config)#spanning-tree backbonefast
Example
In the below example we will configure backbonefast on all switches. After several link failures, we can see that SW4 is correcting SW2’s BPDUs.
SW1(config)#spanning vlan 1-4094 root primary |
SW4(config-if-range)#do show spanning back BackboneFast statistics |