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

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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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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 TroubleshootingAppendix B Glossary Appendix a Technical SpecificationsContents Viii Chapter Introduction About this Manual Your email address Getting HelpDocument Conventions Related Documentation ELS100-16TX Front Panel OverviewSmartSTACK 100 ELS100-16TX Architecture Introduction Autonegotiation Port TrunkingDiscarding Local Trafﬁc Store and Forward SwitchingSpanning Tree Algorithm Typical Switching ApplicationSmartSTACK 100 ELS100-16TX Bridge Address Table SmartSTACK 100 ELS100-16TX Sample Applications SmartSTACK 100 ELS100-16TX Port MirroringSmartSTACK 100 ELS100-16TX Trunking SmartSTACK 100 ELS100-16TX Trunking with 100 Mbps Ports Virtual WorkgroupsRepeater Traffic Workgroup a Workgroup B Local Console Manager Command Syntax Conventions Help Basic LCM CommandsELS100-16TX Local Console Manager Exit or Logout EraseTraplog Introduction ELS100-16TX Front Panel Chapter Unpacking and Installing Your ELS100-16TXPort LEDs 100BASE-T Epim Ports Reset Switch Status LEDs ACT Describes the ELS100-16TX buttons Installing AN EpimInstalling an Epim Rack-Mounting an ELS100-16TX Installing the ELS100-16TXAttaching Rackmount Brackets Connecting the Local Console Manager Checking the POWER-UP Diagnostics SequenceConnecting to the Network ELS100-16TX Twisted Pair Connection Connecting UTP CablesCable Pinouts RJ45 Crossover Cable Connecting a Segment to the EPIM-100FXFiber Optic Network Connection EPIM-100FX Port Unpacking and Installing Your ELS100-16TX Spectrum Spel Spma Chapter Configuring Your ELS100-16TXAssigning 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 BridgingDisplaying Bridging Functions Disabling BridgingEnabling Trunking 100BASE-T Crossover Cables Trunk GroupsTrunk Groups Disabling Trunking Display could look like the following Displaying Trunking StatusEnabled, Rip listening Disabling Mirroring Enabling Port MirroringDisplaying Mirroring Status To check the status for ports conﬁgured for mirroring Deﬁning Virtual Workgroups Defining and Deleting WorkgroupsLCM responds with the following display Assigning a Community Name Configuring BROADCAST/MULTICAST Storm Protection System Contact Modifying MIB VariablesSystem Location System NameCommunity Names Aging Parameter Set Community NameELS100-16TX Management Tools Chapter Monitoring and Managing Your ELS100-16TXELS100-16TX Statistics System Statistics Gathering StatisticsEthernet Port Statistics Displaying Status Using LCM to Check ELS100-16TX StatusEnabled, Rip listening Displaying MAC Addresses To display all MAC addresses, at the LCM prompt LCM would display Displaying Manufacturing InformationManaging the ELS100-16TX Using LCM to Manage the ELS100-16TXEnabling a Port Disabling a PortNoRIP 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 TestsResponses 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 ElectricalStandard Support Diagnostic LEDsSerial Cable PIN Assignments Address Table SizeManagement Support Regulatory Compliance100BASE-T PIN Assignments ConnectorsCrossover Wiring STRAIGHT-THROUGH Wiring5 4 3 Rule EPIM-100FX SpecificationsCable Type Worst Case Budget Typical Budget Technical Speciﬁcations Agent AlarmAddress Address tableBps bits per second BackboneBandwidth Bpdu bridge protocol data unitData rate or speed CongestionData link layer DatagramEntity Full wire speedEncapsulation EncodeInitialization Intelligent bridge/switchIcmp Internet control message protocol IeeeISO International Standards Organization InternetworkingInteroperability IP Internet protocolMIB management information base MAC media access controlMask Mbps megabits per secondPacket Power budgetPropagation delay OSI Open Systems InterconnectionProtocol suite Rarp reverse address resolution protocolService ProtocolTranslating bridge SwitchSymbol Synchronous transmissionWAN wide area network UpstreamGlossary