Re: STP queries

Answer to your 2nd part of question :

You must be knowing that default value of STP timers are decided
keeping in consideration that network diameter is 7 . hence network
diameter of 7 gives hello=2 , fwd delay = 15 and max age = 20 seconds
.

I think What they mean to say is that ; when you change one parameter
; you should make sure other is also changed appropriately .

See below example :

SW1#test spanning-tree diameter 7
diameter 7 and hello time 2 gives max age = 20 and forward delay 15
SW1#

SW1#test spanning-tree diameter 2
diameter 2 and hello time 2 gives max age = 10 and forward delay 7
SW1#

Hence ; if you wish to modify your STP such a way that your network
diameter is 2 ; these are the timers that you need to set on root of
your STP .

I hope I made things clear to you .

Thanks
Gaurav Madan
CCIE # 23863

On Mon, Dec 13, 2010 at 2:15 PM, Faisal Ilyas <faisal.learning_at_gmail.com> wrote:
> Salam,
>
> I have two queries regarding STP 802.1d
>
> 1 - the STP states from disabled->blocking->listening->learning->forwarding.
> If all the switches and its port are in blocking state then how they
> initiate the process of sending BPDU as blocking port is allowed to receive
> only BPDUs so that the switch can hear from other neighboring switches.
>
> 2 - Cisco recommends that if the changes needs to be made, only the network
> diameter value should be modified on the Root Bridge Switch, When the
> diameter is changed, the switch calculates new values for all three STP
> timers automatically. So, how can we change the diameter value ???
>
>
> --
> Regards,
> M. Faisal.
>
>
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Received on Mon Dec 13 2010 - 15:20:22 ART