What is Spanning Tree Protocol (STP)

Broadcast storms are Layer 2 switching loops can cause serious problem to network communication. One of the basic functions of a network switch is to eliminate Layer 2 switching loops.

The function of Spanning Tree Protocol (STP) is to prevent Layer 2 switching loop and broadcast storms in a Local Area Network (LAN). The Spanning Tree Protocol (STP) allows redundant links in a network to prevent complete network failure if an active link fails, without the danger of Layer 2 Switching loops.

Spanning Tree Protocol (STP) is based on an algorithm, which was developed by Radia Perlman at DEC (Digital Equipment Corporation, now part of HP). The Spanning Tree Protocol (STP) was then standardized by IEEE as IEEE 802.1D.

Because of the slow convergence time of Spanning Tree Protocol (STP) IEEE 802.1D, another vesion of Spanning Tree Protocol (STP IEEE 802.1W) is developed, which is also known as Rapid Spanning Tree Protocol (RSTP), which has much better convergence time.

The two implementations of Spanning Tree Protocol (STP) are not compatible with each other. Cisco switches support IEEE 802.1D Spanning Tree Protocol (STP) implementation.