STP Toolkit
Portfast
Portfast allows a port to move immediately to the Forwarding state, bypassing Listening and Learning.
If used, it must be enabled only on ports connected to the end hosts.
If enabled on a port connected to another switch it could cause a Layer 2 loop.
You can also enable portfast with the following command
This enables portfast on all access ports (not trunk ports).
BPDU Guard
If an interface with BPDU Guard enabled receives a BPDU from another switch, the interface will be shut down to prevent a loop from forming.
You can also enable BPDU Guard with the following command:
This enables BPDU Guard on all portfast-enabled interfaces.
To reenable an interface shut down by BPDU Guard, use the command shutdown followed by the command no shutdown. However, if the problem has not been fixed, the interface will soon be shut down again by BPDU Guard.
Root Guard
If you enable root guard on an interface, even if it receives a superior BPDU (lower bridge ID) on that interface, the switch will not accept the new switch as the root bridge. The interface will be disabled.
Loop Guard
If you enable loop guard on an interface, even if the interface stops receiving BPDUs, it will not start forwarding. The interface will be disabled.
Last updated
