Spanning Tree Algorithm | Cabletron Systems 100 manual

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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Cabletron Systems 100 manual Spanning Tree Algorithm, Typical Switching Application

Contents

User Guide Page FCC Notice DOC Notice Cabletron Software Program License Declaration of Conformity Contents ELS100-16TX Diagnostics Troubleshooting Monitoring and Managing Your ELS100-16TX Appendix a Technical Specifications Appendix B Glossary Contents Viii Chapter Introduction About this Manual Getting Help Your email address Document Conventions Related Documentation Overview ELS100-16TX Front Panel SmartSTACK 100 ELS100-16TX Architecture Introduction Port Trunking Autonegotiation Store and Forward Switching Discarding Local Trafﬁc Typical Switching Application Spanning Tree Algorithm SmartSTACK 100 ELS100-16TX Bridge Address Table SmartSTACK 100 ELS100-16TX Port Mirroring SmartSTACK 100 ELS100-16TX Sample Applications SmartSTACK 100 ELS100-16TX Trunking Virtual Workgroups SmartSTACK 100 ELS100-16TX Trunking with 100 Mbps Ports Repeater Traffic Workgroup a Workgroup B Local Console Manager Command Syntax Conventions Basic LCM Commands Help ELS100-16TX Local Console Manager Traplog EraseExit or Logout Introduction Chapter Unpacking and Installing Your ELS100-16TX ELS100-16TX Front Panel Port LEDs 100BASE-T Epim Ports Reset Switch Status LEDs ACT Installing AN Epim Describes the ELS100-16TX buttons Installing an Epim Installing the ELS100-16TX Rack-Mounting an ELS100-16TX Attaching Rackmount Brackets Checking the POWER-UP Diagnostics Sequence Connecting the Local Console Manager Connecting to the Network Connecting UTP Cables ELS100-16TX Twisted Pair Connection Connecting a Segment to the EPIM-100FX Cable Pinouts RJ45 Crossover Cable Fiber Optic Network Connection EPIM-100FX Port Unpacking and Installing Your ELS100-16TX Chapter Configuring Your ELS100-16TX Spectrum Spel Spma Assigning 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 prompt Disabling Bridging Displaying Bridging Functions Enabling Trunking Trunk Groups 100BASE-T Crossover Cables Trunk Groups Disabling Trunking Displaying Trunking Status Display could look like the following Enabled, Rip listening Enabling Port Mirroring Disabling Mirroring Displaying Mirroring Status To check the status for ports conﬁgured for mirroring Defining and Deleting Workgroups Deﬁning Virtual Workgroups LCM responds with the following display Assigning a Community Name Configuring BROADCAST/MULTICAST Storm Protection Modifying MIB Variables System Contact Community Names System NameSystem Location Set Community Name Aging Parameter ELS100-16TX Statistics Chapter Monitoring and Managing Your ELS100-16TXELS100-16TX Management Tools Gathering Statistics System Statistics Ethernet Port Statistics Using LCM to Check ELS100-16TX Status Displaying Status Enabled, Rip listening Displaying MAC Addresses To display all MAC addresses, at the LCM prompt Displaying Manufacturing Information LCM would display Using LCM to Manage the ELS100-16TX Managing the ELS100-16TX Disabling a Port Enabling a Port NoRIP 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 Comparison Status 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 Environmental Diagnostic LEDs Standard Support Address Table Size Management SupportRegulatory Compliance Serial Cable PIN Assignments Connectors 100BASE-T PIN Assignments STRAIGHT-THROUGH Wiring Crossover Wiring EPIM-100FX Specifications 5 4 3 Rule Cable Type Worst Case Budget Typical Budget Technical Speciﬁcations Alarm AddressAddress table Agent Backbone BandwidthBpdu bridge protocol data unit Bps bits per second Congestion Data link layerDatagram Data rate or speed Full wire speed EncapsulationEncode Entity Intelligent bridge/switch Icmp Internet control message protocolIeee Initialization Internetworking InteroperabilityIP Internet protocol ISO International Standards Organization MAC media access control MaskMbps megabits per second MIB management information base Power budget Propagation delayOSI Open Systems Interconnection Packet Rarp reverse address resolution protocol ServiceProtocol Protocol suite Switch SymbolSynchronous transmission Translating bridge Upstream WAN wide area network Glossary