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root switch

Unanswered Question
Apr 2nd, 2006
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is the older switch has higher or lower mac address,

if i get new switch and old switch in a network , and leave them with the default priorities which one will be the root switch

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glen.grant Sun, 04/02/2006 - 14:06
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There is no way to tell if it is higher or lower without looking at it . If you are worried about it you should hardcode spanning tree priority .As best practice you should hardcode anyway unless you have just 2 or 3 switches in your network .

imranmohd Sun, 04/02/2006 - 22:55
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Hi

A root switch or root bridge is the switch with the lower bridge ID.Bridge ID is a combination of bridge priorit+Mac value.

However default priority is 32768.

You can configure a switch as a Root bridge by executing a command.


switch(config)# spanning-tree vlan (vlanid) priority (bridge priority)


Please do rate if works.

ankurbhasin Mon, 04/03/2006 - 00:08
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Hi David,


I am not sure what exactly you want to know but if you bring new switch and old switch in your network and the one which has a lower mac address will become a root bridge.


The selection criteria is priority + mac address which is together known as bridge id.


Now if you have the default priority on all your switches and you connect a new switch with lower mac address it will become a root bridge.


Have a look at this link


http://www.cisco.com/univercd/cc/td/doc/product/lan/c3550/12120ea2/3550scg/swstp.htm#wp1149539


HTH, if yes please rate the post.


Ankur

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