802.1D is the IEEE Media Access Control (MAC) Bridges standard which includes the Spanning Tree Protocol (STP) and Bridging. It details linking to other 802 projects, including the Ethernet and Wi-Fi standards. The Spanning Tree Protocol (STP) is a network protocol that ensures a loop-free topology for a bridged Ethernet local area network. The basic function of STP is to prevent bridge loops. These loops occur when there is more than one Layer 2 path between two endpoints on a network.

IEEE 802.1 Standards for LANs

The set of IEEE 802.1 standards are associated with network management. The standard Spanning Tree Protocol prevents loops when network switches or bridges are connected along multiple paths. The protocol uses the 802.1D algorithim. A bridge protocol data unit (BPDU) can be transmitted across a local area network to detect loops in topologies. Once a loop is detected, it can be removed to achieve a single path between two devices. IEEE 802.1Q is an extension of the MAC Bridging standard. It supports VLAN management.

The Spanning Tree Protocol (STP) and RSTP

Loops can be prevented on the switched LAN by utilizing the Spanning Tree Protocol. Since its original publication, IEEE 802.1D has undergone a number of revisions. The 2004 version incorporates Rapid Spanning Tree Protocol (RSTP), specified by 802.1w. RSTP was developed to gain rapid spanning tree convergence following topology changes. RSTP features backward compatibility with the orginial STP from the earlier 802.1D standard. RSTP supplies bridge port roles for faster RSTP respones after a link failure. Contact Comms Express for questions about industry standards related to network management.

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