Cabletron Systems CSX200 User Manual

Also see for SPECTRUM: User guide User guide User guide User guide Guide

Contents

CSX Bridge View3-30The Spanning Tree Protocol Windowthe Root Identifier parameter in all configuration BPDUs originated from thisnode.Num. Topology Chgs.Indicates the number of times the bridge’s Topology Change flag has beenchanged since the bridge was powered up or initialized. The Topology Changeflag increments each time any of the network’s bridges enters or leaves thenetwork or when the Root Bridge ID changes.The values for the following three fields—Forward Delay, Max Age, and HelloTime—represent the values that are currently being used by all bridges, asdictated by the Root bridge. In the Spanning Tree Protocol window, you can viewand set the values—Root Forward Delay, Root Max Age, Root Hello Time—thatwill be in effect when the bridge for which you are setting the parametersbecomes the Root Bridge.Forward DelayThe length of time, in seconds, that controls how long a bridge port remains ineach state (Forwarding, Learning, Listening, etc.) when moving toward theForwarding state. During a topology change, the Forward Delay is also used asthe Filtering Database Aging Time, which ensures that the Filtering Database willcontain current topology information. The Root Bridge sets the Forward Delay.Max AgeThe current setting for the bridge’s BPDU aging timer, in seconds. The aging timerdefines the maximum number of seconds that a Configuration BPDU is retainedby the bridge before it is discarded. During normal operation, each bridge in thenetwork receives a new Configuration BPDU before the aging timer expires. If thetimer expires before a new Configuration BPDU is received, it indicates that theformer Root is no longer active. The remaining bridges begin Spanning Treeoperation to select a new Root. The Root Bridge determines the Max Age. Therange for this field is from 6 to 40 seconds, with a default value of 20 seconds.Hello TimeIndicates, in seconds, the length of time the Root Bridge, or bridge attempting tobecome the Root, waits before resending a Configuration BPDU. The Root Bridgedetermines the Hello Time.PriorityThe Spanning Tree Algorithm assigns each bridge a unique identifier, which isderived from the individual port’s MAC address and its priority as determinedby the Spanning Tree Algorithm or your setting. The bridge with the lowest valueof bridge identifier is selected as the Root. A lower priority number indicates ahigher priority; a higher priority enhances a bridge’s chance of being selected asthe Root.Acceptable values range from 0-FFFF and can be edited to change the networktopology, if needed. The default is 8000.