D-Link DGS-6600-48TS Configuration Guide - Page 131

Volume 3-Layer 2 Configurations / Chapter 14-Spanning Tree Protocol (STP) Configuration Chapter Overview • Root Path Cost • The Transmitting Bridge ID • The Transmitting Port ID • Hello Time • Forward Delay • Max-Age Priority Vector The purpose of STP is to determine a loop free network topology for the participating nodes and links. STP uses a priority vector mechanism to determine the active topology. There are a number of different priority vectors, which will be described in the following section. All of the priority vectors are formed by the following components: (Root Bridge ID, Root Path Cost, Designated Bridge, Designated Port ID, Bridge Port ID) Figure 14-1 Using Priority Vector Algorithm to Determine Active Topology Algorithms 1) Initially, each bridge assumes that it is the root bridge. The initial root priority vector is: (Bridge ID-X, 0, Bridge ID-X, 0, 0) 2) The bridge calculates the designated priority vector for each port, which will be conveyed in the BDPU that is transmitted to each port. The RPC (Root Path Cost) is initially zero. 3) (Bridge ID-X, 0, Bridge ID-X, Bridge ID-X TX port, Bridge ID-X TX port) DGS-6600 Configuration Guide 131