STP/RSTP States:

STP moves an interface from blocking to listening, then to learning, and then to forwarding state.

• Disabled Port State:

• Disabled ports are Administratively disabled (shut) by an Admin.

• Disabled Port wont be able to Send/Receive any BPDU, Learn MAC Address or Forward Data Packets.

Blocking State:

• Non-Designated Ports are in a Blocking State to block the port on the loop to break the loop.

• Initially all the ports are in a Blocking State but even after Election one port is blocked and that is the Non-Designated Ports which is then again put in the Blocking State.

• In Blocking State, Non-Designated Ports will just be able to receive the RB BPDUs but won't be able to Receive any BPDU, Learn MAC Address or Forward Data Packets.

  Listening State:

• After 20 seconds of Max-Age timer port goes from Blocking to the Listening State.

• In Listening State, ports will send and receive BPDUs in those 15 seconds but won't be learning MAC Address or Forward Data Packets.

• The switch removes old stale (unused) MAC table entries for which no frames are received from from each MAC Address during this period which may cause the temporary loops.

  Learning State:

• In Learning State, ports will send & receive BPDUs & will also learn the MAC Address in those 15 seconds but won't be able to Forward the Data Packets.

  Forwarding State:

• Root Ports & the Designated Ports are in Forwarding State.

• In Forwarding State, ports will not only be able to Send & Receive the BPDUs but will also be able to Learn the MAC Addresses & Forward the Data Packets.

Reference:

• CCNA 200-301 OCG, Volume 1, Pg. 227 - Wendell Odom.

• https://vimeo.com/ondemand/ccna200301/397383497?autoplay=1