Cabletron Systems 100 manual Spanning Tree Algorithm, Typical Switching Application

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Introduction

FastNetELS10010-16TX

LAN 1

LAN 2

A B C

Figure 1-3. Typical Switching Application

By forwarding only packets addressed to devices on other network segments, the SmartSTACK 100 ELS100-16TX reduces unnecessary trafﬁc and thereby enhances the overall performance of the network.

Note: If the packet address is not found in the Bridge Address Table, it will be forwarded (flooded) to all network segments.

Spanning Tree Algorithm

The SmartSTACK 100 ELS100-16TX supports the IEEE 802.1d Spanning Tree algorithm. The Spanning Tree algorithm converts multiple LANs into a “spanning tree” of networks. It is used to prevent bridging loops. This standard deﬁnes a logical (not physical) network conﬁguration consisting of one extended LAN without active duplicate paths between spanning tree bridges.

The SmartSTACK 100 ELS100-16TX, along with other IEEE 802.1d Spanning Tree compliant bridges in the network, dynamically conﬁgure the network topology into a single Spanning Tree by exchanging Bridge Protocol Data Units (BPDUs). Typically, each LAN segment is sent one BPDU every two seconds (this is the default setting).

When there are multiple SmartSTACK 100 ELS100-16TXs connecting LANs in a loop, the Spanning Tree algorithm determines which SmartSTACK 100 ELS100-16TX should forward

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Contents User Guide Page FCC Notice DOC Notice Cabletron Software Program License Declaration of Conformity Contents ELS100-16TX Diagnostics Troubleshooting Monitoring and Managing Your ELS100-16TXAppendix a Technical Specifications Appendix B GlossaryContents Viii Chapter Introduction About this Manual Getting Help Your email addressDocument Conventions Related Documentation Overview ELS100-16TX Front PanelSmartSTACK 100 ELS100-16TX Architecture Introduction Port Trunking AutonegotiationStore and Forward Switching Discarding Local TrafﬁcTypical Switching Application Spanning Tree AlgorithmSmartSTACK 100 ELS100-16TX Bridge Address Table SmartSTACK 100 ELS100-16TX Port Mirroring SmartSTACK 100 ELS100-16TX Sample ApplicationsSmartSTACK 100 ELS100-16TX Trunking Virtual Workgroups SmartSTACK 100 ELS100-16TX Trunking with 100 Mbps PortsRepeater Traffic Workgroup a Workgroup B Local Console Manager Command Syntax Conventions Basic LCM Commands HelpELS100-16TX Local Console Manager Traplog EraseExit or Logout Introduction Chapter Unpacking and Installing Your ELS100-16TX ELS100-16TX Front PanelPort LEDs 100BASE-T Epim Ports Reset Switch Status LEDs ACT Installing AN Epim Describes the ELS100-16TX buttonsInstalling an Epim Installing the ELS100-16TX Rack-Mounting an ELS100-16TXAttaching Rackmount Brackets Checking the POWER-UP Diagnostics Sequence Connecting the Local Console ManagerConnecting to the Network Connecting UTP Cables ELS100-16TX Twisted Pair ConnectionConnecting a Segment to the EPIM-100FX Cable Pinouts RJ45 Crossover CableFiber Optic Network Connection EPIM-100FX Port Unpacking and Installing Your ELS100-16TX Chapter Configuring Your ELS100-16TX Spectrum Spel SpmaAssigning IP Addresses Type ipaddr PORT-NUMBER IP Address Changing a Subnet Mask Displaying IP AddressesDeleting an IP Address Enabling Bridging To change the subnet mask, at the LCM promptDisabling Bridging Displaying Bridging FunctionsEnabling Trunking Trunk Groups 100BASE-T Crossover CablesTrunk Groups Disabling Trunking Displaying Trunking Status Display could look like the followingEnabled, Rip listening Enabling Port Mirroring Disabling MirroringDisplaying Mirroring Status To check the status for ports conﬁgured for mirroring Defining and Deleting Workgroups Deﬁning Virtual WorkgroupsLCM responds with the following display Assigning a Community Name Configuring BROADCAST/MULTICAST Storm Protection Modifying MIB Variables System ContactCommunity Names System NameSystem Location Set Community Name Aging ParameterELS100-16TX Statistics Chapter Monitoring and Managing Your ELS100-16TXELS100-16TX Management Tools Gathering Statistics System StatisticsEthernet Port Statistics Using LCM to Check ELS100-16TX Status Displaying StatusEnabled, Rip listening Displaying MAC Addresses To display all MAC addresses, at the LCM prompt Displaying Manufacturing Information LCM would displayUsing LCM to Manage the ELS100-16TX Managing the ELS100-16TXDisabling a Port Enabling a PortNoRIP Option Changing a Community Name Setting the Baud Rate Setting a Reboot Time Power-up LED Sequence Chapter ELS100-16TX Diagnostics and TroubleshootingPOWER-UP Diagnostics Speciﬁc Power-up Tests Software Checksum ComparisonStatus and Activity Indicators Power-up Diagnostics ResultsResponses to Failures AT POWER-UP ELS100-16TX Front Panel LEDs ACT ELS100-16TX does not Power UP 3 ELS100-16TX Does Not Respond to NMS Connectivity Problems2 ELS100-16TX Has Rebooted ELS100-16TX Diagnostics and Troubleshooting Connector Ports PhysicalElectrical EnvironmentalDiagnostic LEDs Standard SupportAddress Table Size Management SupportRegulatory Compliance Serial Cable PIN AssignmentsConnectors 100BASE-T PIN AssignmentsSTRAIGHT-THROUGH Wiring Crossover WiringEPIM-100FX Specifications 5 4 3 RuleCable Type Worst Case Budget Typical Budget Technical Speciﬁcations Alarm AddressAddress table AgentBackbone BandwidthBpdu bridge protocol data unit Bps bits per secondCongestion Data link layerDatagram Data rate or speedFull wire speed EncapsulationEncode EntityIntelligent bridge/switch Icmp Internet control message protocolIeee InitializationInternetworking InteroperabilityIP Internet protocol ISO International Standards OrganizationMAC media access control MaskMbps megabits per second MIB management information basePower budget Propagation delayOSI Open Systems Interconnection PacketRarp reverse address resolution protocol ServiceProtocol Protocol suiteSwitch SymbolSynchronous transmission Translating bridgeUpstream WAN wide area networkGlossary