Spanning Tree considerations

1. BPDU Protection

Used for access layer switches to prevent a spanning-tree failure on the switch, and to receive bpdus on a port with BPDU-guard enabled, when the err-disable state

Inter G1/1

Spanning-tree Bpduguard Enable

2. Root protection

For all switches, the switch to prevent new access has a higher priority than the root bridge caused by the spanning tree failure. When a higher-priority BPDU is received, the interface is root-nonconsistent State,

Show Spanning-tree Inconsistentport for viewing interfaces belonging to this state

3. Backbonefast

For all switches, when a non-direct-attached port is detected, the block's port is immediately listening, with less than 20s of transition time

4. Uplinkfast

For all access switches, when a direct-attached port is detected, the block's port is immediately forwarding and the entire process is completed in 5s

Spanning Tree considerations