Enables the Port Fast feature on an interface to allow the interface to quickly transition to forwarding state.
Port Fast is disabled.
Interface subtype configuration mode
This command is applicable the only for the Spanning Tree Protocol (STP). Port Fast immediately puts the interface into the forwarding state without having to wait for the standard forward time. Use the spanning-tree edgeport command for MSTP and RSTP.
BPDU guard disables all portfast-enabled ports should they ever receive BPDU frames. It does not prevent transmitting of BPDU frames.
If you enable spanning-tree portfast bpdu-guard on an interface and the interface receives a BPDU, the software disables the interface and puts the interface in the ERR_DISABLE state.
Enable Port Fast on ports connected to host. Enabling Port Fast on interfaces connected to switches, bridges, hubs, and so on can cause temporary bridging loops, in both trunking and nontrunking mode.
To enable a port to quickly transition to the forwarding state:
device# configure terminal device(config)# interface ethernet 1/5 device(conf-if-eth-1/5)# spanning-tree portfast
To guard the port against reception of BPDUs:
device# configure terminal device(config)# interface ethernet 1/5 device(conf-if-eth-1/5)# spanning-tree portfast device(conf-if-eth-1/5)# spanning-tree portfast bpdu-guard