Fast Convergence

Fast Convergence
If you have only layer 2 devices at the core layer, the STP will be used to stop network loops if
there is more than one connection between core devices. The STP has a convergence time of
more than 50 seconds, and if the network is large, this can cause an enormous number of problems
if it has just one link failure.
STP is not implemented in the core if you have layer 3 devices. Routing protocols, which can
have a much faster convergence time than STP, are used to maintain the network.