The Spanning Tree Protocol, also known as STP, was produced to achieve a methodology in which bridges can achieve Layer 2 routing with redundant, loop-free operation. Spanning tree protocol is defined as a protocol in which two bridges interconnect two computer network segments and allow the bridges to exchange information. This way only one of the bridges will be responsible for handling a message sent between both computers within the same network. Removing STP and connecting the switches in a loop will result in duplication of the transmitted packet since there is nothing at layer 2 that can work to prevent a loop. STP exchanges BPDU messages with other switches to detect loops. BPDU is just one of the necessary components that STP uses to do its job. STP also uses other components which include, but are not limited to, root port, block port, and designated port. Say no to plagiarism. Get a tailor-made essay on "Why Violent Video Games Shouldn't Be Banned"? Get an original essayBridge Protocol Data Unit (BPDU) is a data message that is exchanged between switches transmitted by frames on a LAN. BDPU is used to detect loops in network topologies. BPDU frames contain information regarding switch ID, addresses, MAC address, source switch ports, and switch port priority. The information contained in BPDU is necessary to configure an STP topology and maintain it. BPDU informs other switches of port changes. BPDU is actively used in STP when using the tree spanning algorithm (STA). What happens is that when BPDUs are received, the switch uses a mathematical formula, the spanning tree algorithm. It is used to know when there is a layer 2 switching loop in the network. This subsequently determines which of the ports will eventually need to be closed and deactivated. There are actually three types of BPDUs. These are Configuration BPDU (CBPDU), Topology Change Notification (TCN), and Topology Change Notification Acknowledgment (TCA). The CBPDU is a packet that is sent between bridges in a network to configure device interfaces. This operation is performed in a forwarding or blocking state. The TCN is used by the bridge when it needs to signal a topology change. TCN is sent on the root port of the bridge. The TCA is used to acknowledge receipt of a configuration message. The main use and goal of implementing Bridge Protocol Data Units with spanning tree algorithm is to avoid layer 2 switching loops and also something known as broadcast storm. By using the units made up of the BPDU this objective can be achieved. A bridge contains two or possibly more ports. The two that are often confused and are definitely found on the bridge are the root and the designated ports. The port connected on the same side where the STP root can be located is the root port. The root port is the port on the bridge, or switch, that has the least cost of the spanning tree path extending from the root bridge to the switch. There is and can be only one root port on a bridge. When a bridge has more than one path to choose from to reach the root bridge, the bridge chooses one path, usually the shortest, to designate as the root port. A root port can also be identified as a port facing "upstream" and always facing, or pointing, at the root bridge. A designated port is the port on a local area network (LAN) segment that has the least cost path to reach the root bridge. This sounds very similar to what the root port definition is. However, a root port can never be.