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Cabletron Systems manual SmartSTACK 100 ELS100-16TX Bridge Address Table

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Introduction

packets to the LAN. If there is a cable break or a port failure, the network topology is automatically reconﬁgured by the Spanning Tree protocol to create an alternate path to the LAN.

1.5.2SmartSTACK 100 ELS100-16TX Bridge Address Table

The SmartSTACK 100 ELS100-16TX creates and maintains a dynamic database of addresses called the Bridge Address Table. The SmartSTACK 100 ELS100-16TX examines every packet to determine its source address and LAN segment origin. It then compares the source address and segment information it ﬁnds to the entries in the Bridge Address Table.

If a packet’s address is not already stored in the Bridge Address Table, the SmartSTACK 100 ELS100-16TX adds the learned address, associated segment number, and a timer value indicating the age of the observation. Consequently, the SmartSTACK 100 ELS100-16TX knows the address and associated segment number the next time it sees that address. By using the information stored in the Bridge Address Table, the SmartSTACK 100 ELS100-16TX is able to quickly forward each packet to the correct LAN segment.

The SmartSTACK 100 ELS100-16TX learns addresses from all packets, including data transmissions and “keep alive” packets (packets sent by an idle station to let other stations know it is present and functional). When devices are added to the network, removed from it, or relocated, you do not have to reconﬁgure the SmartSTACK 100 ELS100-16TX. The unit automatically learns new device addresses, recognizes when a previously used address is missing, or when a device has been moved to a new LAN segment.

An address stored in the Bridge Address Table is discarded if there is no subsequent activity from that address after a conﬁgured length of time (ﬁve minutes by default). This aging process ensures that the Bridge Address Table is continually updated.

Addresses are continually added to and deleted from the Bridge Address Table, reﬂecting the dynamic nature of internetwork trafﬁc.

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Cabletron Systems manual SmartSTACK 100 ELS100-16TX Bridge Address Table

Contents

User Guide Page FCC Notice DOC Notice Cabletron Software Program License Declaration of Conformity Contents Monitoring and Managing Your ELS100-16TX ELS100-16TX Diagnostics Troubleshooting Appendix B Glossary Appendix a Technical Specifications Contents Viii Chapter Introduction About this Manual Your email address Getting Help Document Conventions Related Documentation ELS100-16TX Front Panel Overview SmartSTACK 100 ELS100-16TX Architecture Introduction Autonegotiation Port Trunking Discarding Local Trafﬁc Store and Forward Switching Spanning Tree Algorithm Typical Switching Application SmartSTACK 100 ELS100-16TX Bridge Address Table SmartSTACK 100 ELS100-16TX Sample Applications SmartSTACK 100 ELS100-16TX Port Mirroring SmartSTACK 100 ELS100-16TX Trunking SmartSTACK 100 ELS100-16TX Trunking with 100 Mbps Ports Virtual Workgroups Repeater Traffic Workgroup a Workgroup B Local Console Manager Command Syntax Conventions Help Basic LCM Commands ELS100-16TX Local Console Manager Erase Exit or LogoutTraplog Introduction ELS100-16TX Front Panel Chapter Unpacking and Installing Your ELS100-16TX Port LEDs 100BASE-T Epim Ports Reset Switch Status LEDs ACT Describes the ELS100-16TX buttons Installing AN Epim Installing an Epim Rack-Mounting an ELS100-16TX Installing the ELS100-16TX Attaching Rackmount Brackets Connecting the Local Console Manager Checking the POWER-UP Diagnostics Sequence Connecting to the Network ELS100-16TX Twisted Pair Connection Connecting UTP Cables Cable Pinouts RJ45 Crossover Cable Connecting a Segment to the EPIM-100FX Fiber Optic Network Connection EPIM-100FX Port Unpacking and Installing Your ELS100-16TX Spectrum Spel Spma Chapter Configuring Your ELS100-16TX Assigning IP Addresses Type ipaddr PORT-NUMBER IP Address Displaying IP Addresses Deleting an IP AddressChanging a Subnet Mask To change the subnet mask, at the LCM prompt Enabling Bridging Displaying Bridging Functions Disabling Bridging Enabling Trunking 100BASE-T Crossover Cables Trunk Groups Trunk Groups Disabling Trunking Display could look like the following Displaying Trunking Status Enabled, Rip listening Disabling Mirroring Enabling Port Mirroring Displaying Mirroring Status To check the status for ports conﬁgured for mirroring Deﬁning Virtual Workgroups Defining and Deleting Workgroups LCM responds with the following display Assigning a Community Name Configuring BROADCAST/MULTICAST Storm Protection System Contact Modifying MIB Variables System Name System LocationCommunity Names Aging Parameter Set Community Name Chapter Monitoring and Managing Your ELS100-16TX ELS100-16TX Management ToolsELS100-16TX Statistics System Statistics Gathering Statistics Ethernet Port Statistics Displaying Status Using LCM to Check ELS100-16TX Status Enabled, Rip listening Displaying MAC Addresses To display all MAC addresses, at the LCM prompt LCM would display Displaying Manufacturing Information Managing the ELS100-16TX Using LCM to Manage the ELS100-16TX Enabling a Port Disabling a Port NoRIP Option Changing a Community Name Setting the Baud Rate Setting a Reboot Time Chapter ELS100-16TX Diagnostics and Troubleshooting POWER-UP DiagnosticsPower-up LED Sequence Software Checksum Comparison Speciﬁc Power-up Tests Power-up Diagnostics Results Responses to Failures AT POWER-UPStatus and Activity Indicators ELS100-16TX Front Panel LEDs ACT ELS100-16TX does not Power UP Connectivity Problems 2 ELS100-16TX Has Rebooted3 ELS100-16TX Does Not Respond to NMS ELS100-16TX Diagnostics and Troubleshooting Physical Connector PortsElectrical Environmental Standard Support Diagnostic LEDs Management Support Address Table SizeRegulatory Compliance Serial Cable PIN Assignments 100BASE-T PIN Assignments Connectors Crossover Wiring STRAIGHT-THROUGH Wiring 5 4 3 Rule EPIM-100FX Specifications Cable Type Worst Case Budget Typical Budget Technical Speciﬁcations Address AlarmAddress table Agent Bandwidth BackboneBpdu bridge protocol data unit Bps bits per second Data link layer CongestionDatagram Data rate or speed Encapsulation Full wire speedEncode Entity Icmp Internet control message protocol Intelligent bridge/switchIeee Initialization Interoperability InternetworkingIP Internet protocol ISO International Standards Organization Mask MAC media access controlMbps megabits per second MIB management information base Propagation delay Power budgetOSI Open Systems Interconnection Packet Service Rarp reverse address resolution protocolProtocol Protocol suite Symbol SwitchSynchronous transmission Translating bridge WAN wide area network Upstream Glossary