you're out of your tree...

a disabled port does not participate in spanning tree; it is either administratively down, or faulty... it does not block,  it is down

a blocked port is participating in spanning tree; it blocks, yet receives bpdu's

a port moves to the listening state when determined it has the potential to forward; it is transitioning.  it is not
   sending or receiving frames, and like blocking it is receiving bpdu's but it is not sending bpdu's; it is
   transitioning to the learning state

a port transitions from listening to learning before it gets to forwarding.  in the learning state the port is now
   adding mac's to it's table. it is one step closer to forwarding.  if it loses its potential, it will revert to blocking.

forwarding... the port has made it to the show after the requisite delays in the tranistory states.  it is adding mac addresses to its table, it is sending and receiving frames and bpdu's... it is in the big's...

spanning tree, i do love thee...

spanning-tree never tires me...

rstp (802.1w) introduced new port roles; among them, discarding.  discarding replaces the
traditional roles of disabled, blocking and listening, leaving only discarding, learning
and forwarding.  discarding is in the active topology as a replacement during the
listening phase of spanning tree but still does not populate mac addresses, just as
listening doesn't in STP. so although discarding has replaced listening, discarding during
the listening phase is considered part of the active topology. this is kind of a silly point because ultimately the role is called discarding yet part of the active topology.  go fish. i guess it's actively discarding...

again, rstp only defines a discarding state from disabled through listening.

alternate and blocked ports in rstp:
An alternate port receives more useful BPDUs from another bridge and is a port blocked.

A backup port receives more useful BPDUs from the same bridge it is on and is a port
blocked.

a port blocked here is important, as opposed to a blocked port.  there are no blocked ports in rstp.

i didn't make this shit up...

Stinky Toilet Paper...

this is gonna hurt you more than me...
spanning-tree port states... arrrrrrrrrrrrrrgh

after initializing, a switchport always enters the blocking state

blocking:
the port dumps the frames received
dumps frames switched for forwarding from another switch
doesn't learn shit
receives bpdu's

listening:

the port dumps the frames received
dumps frames switched for forwarding from another switch
doesn't learn shit
receives bpdu's

learning:
the port dumps the frames received
dumps frames switched for forwarding from another switch
finally gets off its dead ass and learns addresses
receives bpdu's

forwarding:
receives and forwards frames
forwards frames switched from another port
learns addresses
receives bpdu's

disabled:
doesn't do shit