STP and VLANS

is spanning tree per physical switch or per vlan by default??? i'm pretty sure its by physical switch and that there would be extra configs to be per vlan.

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Comments

nice343

spanning-tree is Per vlan by default.

by default the only vlan on a swiitch is 1

when you create multiple vlans on the switch, and connected them to other switches (or not) spanning tree will elect a root brige for every vlan.

If you don't like lets say switch 1 to be the root brige of vlan 20

all you have to do is go into another switch and type

spanning-tree vlan 20 root primary

networker050184

One thing to remeber about the spanning-tree vlan 20 root primamry command is that it only lowers the priority of the switch, but if another switch is introduced with a lower priority your switch will not remain the root. For this reason I lower the poriotiy all the way to make a bridge the root and don't use the spanning-tree vlan 20 root primary command. Or just make sure you use root guard correctly!

sprinkl3s

Thanks for the clarification.