spanning-tree priority

[lkrucker]

Hello all

I have a simple question:

Does the command "set spantree priority 0 " force the switch

to become root switch or does 0 mean, the switch will never become

root switch ?

thanks for your help

Louis

[Prashanth Krishnappa]

Lower the value, higher the priority. To answer your question, yes it forces the switch to be root. Documents for reference

http://www.cisco.com/warp/public/473/5.html#oper

http://cio.cisco.com/univercd/cc/td/doc/product/lan/cat6000/sw_6_3/cmd_ref/setsy_tr.htm#xtocid0

[bsivasub]

It is highly not recommended to use this command to make the root selection.

it will prevent any other switch to become at a later date (unless ofcourse that is what you want ) until you remove the switch and introduce with a higher priority.

use the set spantree root command instead

[milan.kulik]

You can never be 100% sure that "it will prevent any other switch to become root at a later date". If you connect another switch with priority 0 and a lower MAC address it will become the root!!

Regards,

Milan

[lkrucker]

Thanks for the quick answer, the reason why i ask, i currently doing the labs in karl solies ccie book for ccie.

There i a task where i have to make sure my cat is always root switch. In his solution he configure the priority to 1 instead to 0 and that confused me.

It seems to be an error isnt it ?

set spantree root is (i think) wrong because it does not make sure my switch is always root switch in case a new switch connect.

Louis