Root Devices- Spanning tree protocol Stp

[karanpreet.syngh]

If a network has 23 switches and 10 VLANs how many root devices are elected?

[Tagir Temirgaliyev]

if pvst 10

if mst you can choose from 1 to 10

[karanpreet.syngh]

thnku for replying .

if mst , i can choose from either just 1 root device or 10 root devices? is that right?

[Tagir Temirgaliyev]

in mst you can make 1 instance for all vlans and 1 root switch.

or in mst you can make 2 instances for each 5 vlans and 2 root switch.

and so on

[Julio E. Moisa]

Hi 

You should have 2 root devices, one primary and the secondary. I recommend to select them manually using priorities and select the robust switches. I dont recommend let the selection randomly. Remember the lowest priority is preferred to be the root. If you use Rapid Spanning tree you will have 10 STP instances, 1 for each vlan. And if MST is used you could have 1 STP instance for the 10 vlans.

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:-)