Re: Basic q regarding STP initial convergence

I think you're confusing the listening and blocking states. The blocking
state is when it has already converged and knows to block a port.
Listening is when it's trying to see if it's the root. For example if the
STP algorithm decided a blocking port was going to transition to
forwarding why would it block for an additional 20s before listening and
not passing traffic for an additional forwarding-delay?
HTH,
Keegan

Re: Basic q regarding STP initial convergence

Roy Waterman
to:
Danshtr
08/08/09 04:10 PM

Sent by:
nobody_at_groupstudy.com
Cc:
ccielab
Please respond to Roy Waterman

Never mind, after thinking about it I know the answer ;)
Posted prematurely.

2009/8/8 Danshtr <danshtr_at_gmail.com>

> What will happen when you boot all your switches at the same time?
>
> Best regards,
> Dan
>
>
>
> On Sat, Aug 8, 2009 at 4:25 PM, Roy Waterman
<roy.waterman_at_gmail.com>wrote:
>
>> Hi all
>> In several texts I've read that switches upon convergence each think
they
>> are the root bridge AND send config pdus out all ports.
>> However in Cisco's implementation, with the intial blocking state being
20
>> secs, and having the ability to only receive config pdus from
neighboring
>> switches,
>> while each switch upon initial convergence may THINK they are the root
>> bridge is it true that in general they do not have a chance to
advertise
>> that as a result of possibly receiving a better bpdu from a neighboring
>> switch?
>>
>> Plus, was the initial 20 sec blocking state proposed by Cisco to
actually
>> allow switches enough time to learn the identity of the root bridge
before
>> sending bpdus of their own?
>>
>> Please advise.
>>
>> --
>> Regards
>> Roy
>>
>>
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>>
>

-- 
Regards
Roy
Blogs and organic groups at http://www.ccie.net