Reference v4.1.0 Instruction Manual

Network OS Command Reference 1245

53-1003115-01

spanning-tree portfast

Enables the Port Fast feature on an interface to allow the interface to quickly transition to

forwarding state.

Synopsis spanning-tree portfast [bpdu-filter | bpdu-guard]

Operands bpdu-filter Sets the Port Fast BPDU filter for the port.

bpdu-guard Guards the port against the reception of BPDUs.

Defaults Port Fast is disabled.

Command Modes Interface subtype configuration mode

Description Use this command to enable the Port Fast feature. This command is 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 filter prevents the switch from sending BPDU frames on ports that are enabled with portfast.

BPDU guard disables all portfast-enabled ports should they ever receive BPDU frames. It does not

prevent transmitting of BPDU frames.

Usage Guidelines 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.

If xSTP is enabled over VCS, this command must be executed on all RBridge nodes.

Examples To enable a port to quickly transition to the forwarding state:

switch(config)# interface tengigabitethernet 0/1

switch(conf-if-te-0/1)# spanning-tree portfast

To set the Port Fast BPDU filter for the port:

switch(config)# interface tengigabitethernet 0/1

switch(conf-if-te-0/1)# spanning-tree portfast bpdu-filter

To guard the port against the reception of BPDUs:

switch(config)# interface tengigabitethernet 0/1

switch(conf-if-te-0/1)# spanning-tree portfast bpdu-guard

See Also show spanning-tree, spanning-tree autoedge, spanning-tree edgeport