How to determine the root bridge for STP

[paulnigel]

hi forum,

my switches has only the following turn on when i first installed them:

spanning-tree mode pvst

spanning-tree extend system-id

now that if I want to configure STP & select the core switch as root bridge, will it affect the whole spanning tree, if STP recalculates will it cause all the connected devices to lost connection temporarily?

How do I confirm which one is the root bridge and use back the same root? Why it shows different priority for different VLAN for the root bridge, some 32768, some 32772?

Thanks & Best regards,

Paul

[zerozerotito]

Hi paul!

As you said, if you select root bridge, it will affect whole spanning tree. After you define conre switch as a root bridge, a new stp calculation will be started on all switches...

You can use "Show spanning-tree vlan vlan-id"to see SPT entries... Also you can use 'show spanning-tree detail'

for more information on STP Configuration, check this out

http://www.cisco.com/en/US/products/hw/switches/ps628/products_configuration_guide_chapter09186a00800d84bb.html#23902

Pls Rate all Posts

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[paulnigel]

Hi Zero,

my environment is life, but i have to make the changes. will it bring down my network if I do the STP changes?

for a life environment, what is your recommendation if i need to introduce STP into my network?

Best regards,

paul

[zerozerotito]

Hi Paul!

Well, it will bring down your network for a while.

But it doesnt take too long (depending your network)...

You can find some info about STP Calculations on the following link...

http://www.cisco.com/univercd/cc/td/doc/product/rtrmgmt/sw_ntman/cwsimain/cwsi2/cwsiug2/vlan2/stpapp.htm

You can choose the best time to change STP settings... For example after rush hours...

Rgrds

[paulnigel]

Hi Zero,

Thanks much. my plants is running 24 hours, i hope it doesn't create a havoc, i have a AS400 running too, pretty sensitive.

I will take a look at the document, thanks much,

Best regards,

Paul