This book focuses on one mode only: PVST+. Cisco switches generally default to using PVST+, but
to set a switch to use this mode, use the spanning-tree mode pvst global command. Alternatively,
switches allow RPVST+ with the spanning-tree mode rapid-pvst command, and Multiple Spanning
Tree (MST) with the spanning-tree mode mst command.
All the examples in this chapter use 2960 switches, with PVST+ as the default STP mode.