Exercises with STP

Exercise with STP

Exercise 1..

Which one is the root bridge , root port and designated port in this topology?

Before we start let me bring one more time the tables:

1.-The 32768:69 of Sw2 is less than 32768:79 of Sw1... So SW2 is our Root bridge

2.-The Designated port is the closest to the root bridge, so it would be Fa0/1 of SW2

3.-The Root port is the port of the non bridge: Fa0/1 of SW1

This is the result:

Exercise 2

I this exercise we will assume they have the same port cost, because they have the same interface and speed

1.- In this exercise SW1 has the lowest hexadecimal digit of mac address: 4096 than SW2 and SW3..So it would be the Root bridge
2.- Fa0/1 and Fa0/2 of SW1 are closer to the root bridge so they become the Designated Port
3.-Fa0/1 and Fa0/1 of SW2 and SW3 are the non-root port bridge, closer to the root bridge so they are Root Port
4.- Because all the links we will assume have the same port speed, we will need to disable one of fa0/2 interface of SW2 and SW3..So we will administratively shut down Fa0/2 of SW3, our Disable port

The result is this:

Exercise 3

Here we have different speed : Gigabyte and Fast ethernet interfaces..So it will affect the STP port Cost

First we will point out the STP port cost
In this exercise SW1 has the lowest hexadecimal digit of mac address: 4096 than SW2 and SW3..So it would be the Root bridge
Fa0/1 and Fa0/2 of SW1 are closer to the root bridge so they become the Designated Port
G0/3 of SW2 (cost 4 + 4)and G0/1 (cost 4)of SW3 are the non-root port bridge, closer to the root bridge in term of Cost so they are Root Port
The ones that are not yet label as root port or designated port is going to be our Blocking port, so in this scenario it will be fa0/1 and Gi0/2 of SW2