What STP Does?

Previously we understood STP's main job is to Block a port on the loop to break the Loop. Let us understand What STP does to break that Loop.

• To break the Loop STP put interfaces of each Switch either in a Forwarding State or in a Blocking State.

• Forwarding State:

  • In Forwarding State ports are Forwarding & receiving the Frames.

• Blocking State:

  • In Blocking State ports are not Forwarding Frame. Ports however receiving the Frames but keep on discarding them (except STP/RSTP & and some other overhead messages).

• If however something changes in the LAN (e.g. a running link goes down) then the STP convergence process can also bring the blocked ports up form the Blocking to the Forwarding State.

• Lets take a look at How STP works

Reference:

• CCNA 200-301 OCG, Volume 1, Pg. 215-216 - Wendell Odom.