Spanning Tree and Root Guard
The goal of the lab is to show what happens when a new switch is added to a topology and wins the root bridge election. Generally you don’t want this to occur and should have the primary and secondary root bridge hard coded. Root Guard can be put in place to stop the new switch from becoming the new root for the topology. It will place the port receiving the new better BPDUs in a blocking state. The administrator can then change the root priority to something higher than the original root bridge priority and stop this error from occuring.
In the next post I will go over how to configure portfast and bpdu guard on access ports. This will stop a new switch added to the network from becoming root bridge if plugged into one of the access ports.