Cisco Spanning Tree Protocol (STP) Basics

Cisco Spanning Tree Protocol (STP) Basics

Spanning Tree Protocol (STP) is a network protocol that builds a loop-free logical topology for Ethernet networks.

Configuring the Root Bridge

Switch# configure terminal
Switch(config)# spanning-tree mode pvst
Switch(config)# spanning-tree vlan 10 root primary
Switch(config)# spanning-tree vlan 20 root secondary
Switch(config)# spanning-tree vlan 30 priority 4096

Configuring PortFast

Use PortFast on edge ports connected to end devices to skip listening and learning states.

Switch(config)# interface fastethernet 0/1
Switch(config-if)# spanning-tree portfast

Verification Commands

  • show spanning-tree
  • show spanning-tree vlan 10
  • show spanning-tree summary