what layer is stp
This article covers the most frequent STP errors and how to correct them. The IEEE 802.1D Spanning Tree Protocol (STP) was invented by Radia Pearlman in 1985 when working at Digital Equipment Corporation (DEC). STP is a layer-2 protocol that runs between bridges to help create a loop-free network topology. Bridge Protocol Data Units (BPDUs) are packets sent between Ethernet switches (essentially multi-port bridges) to elect a root bridge, calculate the best path to the root and block any ports that create loops.