Store and Forward Switching | Cabletron Systems 100 guide

Introduction

ports allowing the switch port and an attached device to negotiate for full or half-duplex modes of operation. The SmartSTACK 100 ELS100-16TX also supports auto-negotiation as deﬁned by IEEE 802.3u and will automatically set the port to the proper mode (10 Mbps, half/full duplex or, 100 Mbps half/full duplex). The EPIM100-FX interface will not support auto-negotiation, as auto negotiation for ﬁber is not deﬁned in the 802.3u speciﬁcation.

Store and Forward Switching

As an intelligent Ethernet switch, the SmartSTACK 100 ELS100-16TX uses store and forward switching. Store and forward switching allows the SmartSTACK 100 ELS100-16TX to temporarily store packets until network resources, typically an unused link, are available for forwarding. This allows for complete error checking, and limits the amount of time between when a device requests access to the network and when it is granted permission to transmit. In addition, full store and forward switching ensures data integrity, thus preventing network error conditions from being generated throughout the network.

Discarding Local Trafﬁc

The SmartSTACK 100 ELS100-16TX checks all incoming packets for their destination address against the Bridge Address Table. If a packet’s destination address is not on the same network segment as the originating packet, the SmartSTACK 100 ELS100-16TX forwards the packet to the network segment associated with that destination address, if known. However, if the packet’s source and destination address are on the same network segment, known as local trafﬁc, the packet is automatically discarded (i.e., ignored by the SmartSTACK 100 ELS100-16TX).

For example, a ﬁle transmitted from Workstation A to Workstation C in Figure 1-3 does not need to leave LAN 1. The SmartSTACK 100 ELS100-16TX connected to LANs 1 and 2 sees all trafﬁc from LAN 1, including LAN 1 local trafﬁc.

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Cabletron Systems 100 manual Store and Forward Switching, Discarding Local Trafﬁc

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 Exit or Logout EraseTraplog 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 Deleting an IP Address Displaying IP AddressesChanging 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 Location System NameCommunity Names Aging Parameter Set Community Name ELS100-16TX Management Tools Chapter Monitoring and Managing Your ELS100-16TXELS100-16TX 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 POWER-UP Diagnostics Chapter ELS100-16TX Diagnostics and TroubleshootingPower-up LED Sequence Software Checksum Comparison Speciﬁc Power-up Tests Responses to Failures AT POWER-UP Power-up Diagnostics ResultsStatus and Activity Indicators ELS100-16TX Front Panel LEDs ACT ELS100-16TX does not Power UP 2 ELS100-16TX Has Rebooted Connectivity Problems3 ELS100-16TX Does Not Respond to NMS ELS100-16TX Diagnostics and Troubleshooting Environmental Connector PortsPhysical Electrical Standard Support Diagnostic LEDs Serial Cable PIN Assignments Address Table SizeManagement Support Regulatory Compliance 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 Agent AlarmAddress Address table Bps bits per second BackboneBandwidth Bpdu bridge protocol data unit Data rate or speed CongestionData link layer Datagram Entity Full wire speedEncapsulation Encode Initialization Intelligent bridge/switchIcmp Internet control message protocol Ieee ISO International Standards Organization InternetworkingInteroperability IP Internet protocol MIB management information base MAC media access controlMask Mbps megabits per second Packet Power budgetPropagation delay OSI Open Systems Interconnection Protocol suite Rarp reverse address resolution protocolService Protocol Translating bridge SwitchSymbol Synchronous transmission WAN wide area network Upstream Glossary