[c-nsp] STP behavior

[Sergey Velikanov [Intelsoft]]

Hi

I really can't understand how mach times STP(802.1d) need to set up port from blocking state to forwarding

at http://tinyurl.com/fah77 says

Blocking State

A port in the blocking state does not participate in frame forwarding, as shown in Figure C-5. After initialization, a BPDU is sent to each port in the switch. A switch initially 
assumes it is the root until it exchanges BPDUs with other switches. This exchange establishes which switch in the network is really the root. If only one switch resides in the 
network, no exchange occurs, the forward delay timer expires, and the ports move to the listening state. A switch always enters the blocking state following switch initialization.

so port remain 15 sec(forward time) in blocking state if no other switches in network, or until it receive first bpdu?

so summary time is blocking(15 sec, or 2-4 sec?)+listen state(15 sec)+learn state(15 sec) = 35-45 sec ?

but in my test lab i've seen strange behavior

My lab is

Cisco 3560 (RSTP moode) --- Aironet 1300 ( STP mode)

0:00 I've enter no shut command at cisco 3560 on aironet interface

0:05 At "show spanning-tree summary" i've seen that

Name                   Blocking Listening Learning Forwarding STP Active
---------------------- -------- --------- -------- ---------- ----------
VLAN0030                     0         0        0          5          5


changed to


Name                   Blocking Listening Learning Forwarding STP Active
---------------------- -------- --------- -------- ---------- ----------
VLAN0030                     1         0        0          5          6


at 0:20
it changed to


Name                   Blocking Listening Learning Forwarding STP Active
---------------------- -------- --------- -------- ---------- ----------
VLAN0030                     0         0        1          5          6


and at 0:35
it changed to


Name                   Blocking Listening Learning Forwarding STP Active
---------------------- -------- --------- -------- ---------- ----------
VLAN0030                     0         0        0          6          6



I've not seen Listen state!! but total time is about 35 sec

Could any body comment it?