STP Root Guard

Root Guard is an STP feature that prevents a port from becoming a root port. This prevents a downstream switch from becoming a root bridge. This is useful when you have a multi-tenant situation where you don’t have direct control over all of the switches connecting to the network, and you want to make sure that your STP topology remains stable.

For additional STP fine tuning features, take a look at STP fine tuning the spanning tree protocol.