Ive spent the last couple of days playing around with the traditional Spanning-tree protocol (802.1D), which has been used for many years, but is pretty slow to converge. As most of you know, Spanning-tree protocol (STP), is used to build a loop-free L2 topology. This is done to avoid bridging loops, where your frames gets sent around and around endlessly. STP does this by assigning ports a certain role and a state.