How do I enable PortFast on Cisco?

In switch A, run the following commands as port 20 is connected to a host.

  1. Enter the configuration mode for the interface.
  2. Shut down the interface.
  3. Change the portfast setting.
  4. Review the portfast status.
  5. Reset the default spanning tree portfast value for the interface.
  6. Review the portfast status.

What does enabling PortFast on a Switchport do?

Enabling the PortFast feature causes a switch or a trunk port to enter the STP forwarding-state immediately or upon a linkup event, thus bypassing the listening and learning states. The PortFast feature is enabled at a port level, and this port can either be a physical or a logical port.

Why would we want to enable PortFast?

Without PortFast, a PC can send a DHCP request before the port is in forwarding state, denying the host from getting a usable IP address and other information. Because PortFast immediately changes the state to forwarding, the PC always gets a usable IP address.

What is PortFast on Cisco switch?

Portfast feature causes a switch port to enter the spanning tree forwarding state immediately, bypassing the listening and learning states.

How do I enable PortFast by default?

The spanning-tree portfast default global configuration mode command enables PortFast on all non-trunking interfaces. To configure BPDU guard on a Layer 2 access port, use the spanning-tree bpduguard enable interface configuration mode command, as shown in Example 3-6.

Does PortFast disable spanning tree?

A common misunderstanding among Cisco students is that portfast disables spanning-tree on a certain interface. This is not correct however…if you enable portfast on an interface then it will jump to the forwarding state of spanning-tree. We still run spanning-tree on the interface!

Is PortFast enabled by default?

PortFast and BPDU guard are disabled, by default, on all interfaces.

Should I use PortFast?

PortFast feature should be used only to connect a single workstation to a switch port to avoid layer 2 switching loop. Spanning Tree PortFast feature causes a port to enter the forwarding state immediately, bypassing the listening and learning states.

When should I use PortFast?

How do I enable PortFast globally?

Enter global configuration mode. Enter interface configuration mode, and specify an interface to configure. Enable Port Fast on an access port connected to a single workstation or server. By specifying the trunk keyword, you can enable Port Fast on a trunk port.