RSTP Port States and Port Roles

Port States: in STP= blocking, listening, leaning and forwarding

Port Roles: STP=root, designated, 


Port State:


STP802.1d-1998
disableno STP or RSTP enable
Blocking State

drop data frame

don't send BPDU

Only listen BPDU


Listening State

Drop data frame

send cfg BPDU ( Mcst: 01:80:C2/00:00:00 + link local scope )

+ Bridge ID or BID: priority + Mac@

Default BID= 32K 

1- use for election of Root bridge / broadcast network

             Lowest BID win

2- select the designated bridge / segment

            Lowest BID win


1- set the port priority: default 1G= 20K and 10G= 2K

2- send in the BPDU "root path cost"

locally calculate the root path cost, 


3- update the BPDU

1- Set the Port Roles:

            lowest root path cost win

Learning Statesend and learn BPDU
15secForwarding Delay Timerto avoid transient loop
Forwarding Statesend and receive Data frame