PortFast is an optional Spanning Tree Protocol feature that moves a switch port immediately into the forwarding state. It prevents end hosts such as PCs from waiting through the listening and learning states, which normally takes about 30 seconds. section 14.5 section 14.5.1
Configure PortFast with the command that matches the intended scope:
- Use spanning-tree portfast in interface configuration mode for one port. section 14.5.1
- Use spanning-tree portfast default in global configuration mode for all access ports, not trunks. section 14.5.1
- Enable it only on ports intended for end hosts; connecting a switch can create a Layer 2 loop. section 14.5.1
- Pair PortFast with BPDU Guard so a PortFast port can be disabled if it receives a BPDU. section 14.6
Cisco IOS interface configuration
SW1(config)# interface g1/0 SW1(config-if)# spanning-tree portfast The switch warns that PortFast belongs on a port connected to a single host and takes effect only when the interface is non-trunking.
