CHAPTER

Network Hardware

Chapter ObjectivesDescribe the important basic network hardware and the internetworking hardwareDiscuss the desired characteristics of a server and a workstation Present different switching technologiesExamine the routing process with the help of an example

Classification of Basic Network Hardware ComponentsNetwork Interface Cards (NICs)CablesConnectorsServersWorkstations

Classification of Internetworking Hardware ComponentsLine drivers or repeatersTransceiversIntelligent hubsBridgesSwitchesRouters Gateways

Chapter ModulesNetwork interface cardsNetwork connectors and hubsServer and workstation hardwareRepeaterBridgeSwitchContinued..

Continuation of Chapter ModulesSwitching technologyRouterGateway

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MODULE

Network Interface Cards (NICs)

Network Interface Card Types10BaseT cardsPhysical star networks10 Mbps speedEthernet standardTwisted pair wiring10base2 cardsPhysical bus networks10 Mbps speedEthernet standardThin coaxial wiring

Continuation of NIC Types10Base510 Mbps speedEthernet standardThick coaxial wiring100BaseTX100 Mbps speedFast Ethernet standardTwisted pairHigher quality Category 5 wires are recommended

Token Ring CardsToken ring network cardsEarlier token ring cards4 MbpsNewer token ring cards16 Mbps

Bus Types for NICsCard connector typesNewer PCI bus Older ISA, VESA and EISA bus typesISA bus width16-bitPCI bus widthUsually 32-bitSupports 64-bit as wellUsed in high-powered network servers

Cable Connections for NICs BNC barrel connectorThin coaxialRJ 45Twisted pair

AUI and Combo Cable Connections for NICsAUI PossibilitiesDesigned for a thick coaxial cableDesigned for a token ring networkProvided for connecting a transceiverCombo CardsConsisting of different portsBNC, RJ-45, AUI

Possible Combo Card ConnectionsThin coaxial cables (BNC)Twisted pair wires (RJ-45)Thick coaxial cables (AUI)

Description of an Actual NIC10BaseT, PCI card10 = speed in MbpsBase =EthernetT = Twisted pair32-bit = bus widthPCI = bus technology

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MODULESample Network Interface Cards

Example of a 10Base2 CardBNCSource: Black Box

Example of a 10BaseT CardRJ 45ISASource: Black Box

Example of a Combo CardComboSource: Black BoxRJ 45BNC

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MODULENetwork Connectors and Hubs

Simple ConnectorsT connectors An interface between the NIC and the cablesTerminatorsUsed at both ends of a bus networkTerminatorT Connector

Example of T-Connector and TerminatorT ConnectorTerminatorSource: Black Box

Connectors : HubsTypesActive hubPassive hubPassive hubsSimply provides the physical and the electrical connection for the networkActive hubsHas built-in intelligenceSome are manageable hubs

Connectors : Passive HubMAUWSWSHub Connecting A Token-ring NetworkWS

An Active HubBackboneManageable HubRemoteWorkstationWSWSWSRemote MonitorActive Hub

Hub Management SoftwareSophisticatedMonitor the network traffic through each of the portsBecoming popularStandardized protocol for remote management existsSNMP (Simple Network Management Protocol)

Example of a Hub Used in Ring NetworkSource: Black Box

Example of Hubs Used in the Star NetworkStackableHubsSource: Black Box

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MODULEServer and Workstation Hardware

Module ObjectivesGive an overview of the different types of the server hardwareDiscuss the desired characteristics of a serverProvide a specification for a workstation

ServersBackbone of a networkTypesPowerful microsServersSuper-serversSometimes mini-computers are used as serversIn a client-server, the server also acts as an engine of database executionIn general, it is used for the sharing of stored data and application

Desired Characteristics of Server: Processor and Storage RequirementPowerful processorLatest Pentium ProcessorMultiple processors, if appropriateLarge storage spaceSeveral gigabytes at a minimumActual requirement will vary LAN sizeFast disk access speed Less than 10 ms

Desired Characteristics of a Server: CD-ROMFast CD-ROM drivesCD-ROM towers are often preferred

Desired Characteristics of Server: Storage TechnologyBetter hard disk technologySCSIFast accessDaisy chaining of devicesLatest SCSI technology is required Possible consideration given to fiber-channel in the future

Desired Characteristics of Server: Bus and Memory TechnologiesBetter bus technologyPCIMemoryIn excess of 128 MbytesSDRAM or similar memory technology functioning at 10 nanoseconds or lessThe 128-pin SDRAM is also known as the DIMM chips as opposed to the 72-pin SIMM chips

Desired Characteristics of Server: Reliability Good back-up facilitiesBack-up tapeUniterruptible Power Supply (UPS)

Fault Tolerant Feature for ServersRAID storage technologyA system based on multiple diskHot-swappable disksRedundant power supplyHot-swappable power supply

Workstation Most applications are executed at the workstationTherefore, it must be powerful in terms of the processor and the memoryAs a rule of thumb, the workstation must be as powerful as it were to be used as a standalone unit to run the applications

Workstation Processor and MemoryPowerful processorPentium class processorAdequate memory 32 Mbytes or moreDIMM preferred although fast EDO SIMM may also be used

Workstation Storage and Compatibility Sufficient storageStorage in gigabytesImportant in a client-server environmentFront-end tools are stored on the workstationSpeed of storageUltra DMA or SCSI preferred EIDE may also be usedHardware components with appropriate drivers for the client operating system

ReliabilityPower surge protectorUninterruptible Power Supply (UPS), for critical applications

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MODULERepeater

An Overview of RepeatersUsed for extending the physical span of a networkAn example is the extension of the distance between a hub and a nodeSpan is often limited by design considerations 10base5 The span is limited to 500 meters

A Repeater ConnectionExpanding the Span of the Network Source: Black Box

Another Example of Repeater Connection Extending the distance between the backbone and the nodes. Source: Black Box

Operations of a Repeater Within the ISO OSI ModelOperates at the lower level of the ISO OSI modelPhysical layerMediumPhysicalLayerRepeaterMediumPhysical Layer

Other Devices Used for Extending the Span of a NetworkLine DriversShort-Haul Modems

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MODULEBridge

An Overview of a BridgeA device used for connecting two LANs operating under the same protocolCurrently, the term bridge is loosely being used to describe different interconnecting devicesUsed now for connecting LANs operating under different protocols as well

Purpose of a BridgeFacilitate the movement of data packet from one network segment to anotherNot a sophisticated internetworking deviceBridge does not perform the routing of information to different segments of a network Connects two network segments and not multiple network segments

Bridge : ISO-OSI Layer of OperationBridgeX MediumX MediumPhysical LayerPhysicalLayerDataLinkLayerDataLink LayerA simple bridge operates at the second layer of the ISO model.

Practical Bridge ImplementationsLocal BridgeRemote Bridge

Local and Remote BridgesLocal bridgeConnects two different LANs located locallyRemote bridgeConnects LAN segments that are geographically apartAn example is a device that provide dial-up access to a LAN

A Practical Bridge ExampleSource: Black Box

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MODULESwitch

Switch Definition and PurposeA switch is defined as a device that allows a LAN to be segmented The segments will operate under the same protocol

Difference Between a Switch and a BridgeA switch focuses on segmenting a LANA bridge is concerned with linking two network segments that operate under different protocols

Purpose of a SwitchImprove the network performance and reliability Better manage the network in general

Performance Improvement in Segmented NetworksPerformance is improved especially in the case of a bus networkMultiple bus paths are now available for communicationEach segment can engage in simultaneous communication within itselfEasier to isolate a problem to a segmentThus, better manage the entire network

Network ReliabilityWhen one segment does not function, the other segments can continue to functionOffers better reliability to at least part of the function

Switches in Ethernet and Token Ring LANsSwitches were originally designed for segmenting Ethernet LANsUsed extensively in configuring large Ethernet bus LANsPhysically the network configured would still largely remain based on the star topology Switches are now available for token ring networks as well

Use of Switches in Linking LAN SegmentsSwitchHubHubWSServerWSServerSegment 1Segment 2Crossover Traffic

Using A Switch to Link Bus LAN SegmentsSwitchSegment 1Segment 2

Use of Switches in InternetworkingBecause the typical inter-networking connection involves multiple segments, the use of a switch is more common than the use of a bridge

Use of Switches for Higher BandwidthWS100 MBps SwitchWSWSWSEach port in theory has a bandwidth of 100 Mbps.

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MODULESwitching Technology

Module ObjectivesExplain the basic operation of a switchList the switching technologies and describe their operationCut-through and store-and-forward technologies

The Basic Operation of Switches

A data packet is analyzedReceivers addresses is checkedIf it indicates the receiver to be in the same segment, the packet is droppedIf it indicates the receiver to be in a different segment, the packet is forwarded to a different segment Receivers Address Senders Address Data

Switching TechnologiesThere are two major types of switching technologiesCut-throughStore-and-forward

Cut-Through TechnologyReads only part of the packetThe addresses headerPacket is forwarded accordinglyBad packets are not filtered

Store-and-Forward TechnologyEntire packet is processedPackets are filteredBad packets are filtered

Switching Technology ComparisonHeaderSenders AddReceivers Add DataCut-throughStore-and-forward

Switching Technology Operation at the ISO LayerIn each of the two cases of switching technologies no protocol conversion takes placeForwarding and filtering are done at the MAC layer

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MODULERouters

The Purpose of a RouterConnect LANs operating under different protocolsThe LANs connected are better known as sub-networks instead of network segmentsThe term segments is nevertheless used in practice

Router CharacteristicsA router true internetworking deviceConnects different sub-networks togetherEstablishes a logical path of communication between the sub-networksContributes to the modular construction of a networkNetwork itself is better managedNetwork resources are better utilized

Internetworking with a RouterIEEE 802.3Sub-networkIEEE 802.5Sub-networkPC-NFSSub-networkRouter

Routers, Switches and Hubs in PerspectiveSwitchSwitchHubHubSWSWSWSRouterHubSWSHubWSSHubWSWSHubWSSSub-network 1Sub-network 2Backbone

Difference Between Routers, Switches and HubsHubsSimply provides the mechanical and electrical connections between the nodesSwitchesExamine the data packet for the destination addressDo not alter the data packetsRoutersExamine and alter the data packetsPerform protocol conversion

Router RequirementsRequires more processing power compared to switches and bridgesOperations fall within the network layer of the ISO-OSI communication model

Router : Network Layer InterfaceX MEDIUMX MEDIUMPHYSICAL LAYERPHYSICALLAYERDATA LINKLAYERDATA LINKLAYERNETWORKLAYERROUTERNETWORKLAYER

Devices and LayersPHYSICAL LAYERDATA LINKLAYERNETWORKLAYERSwitchesRoutersRepeatersSwitchesLayer 1Layer 2Layer 3

A Practical Router ExampleRouterRouterRouterRouterRouterSource: Black Box

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MODULEGateway

An Introduction to GatewaysGateways are comprehensive internetworking devicesThey can be computers themselves

Gateways in the PastVery popularThey were the only devices that could be used for internetworkingComputers of the past were not designed with network connections in mindInterconnection of different computer systems has to be managed and driven by an advanced device such as a gateway

The Present ScenarioComputers are now designed with due consideration given to network connectionsLarger networks could today be configured using internetworking devices Routers, switches, hubs etc.

Use of Gateways at PresentUsed in the rare occasion when neither of the internetworking devices could be used for connecting the sub-networks togetherExampleConnection of a legacy mainframe system to a bus LAN

Rule of ThumpGateways are used for interconnecting vastly differing computing environments together

SNA Gateway

SNA GatewayWSWSMainframeLAN - EthernetIBM - SNAFEPNIC CardGateway softwareGatewayInterfaceCard

Gateways Functional Relationship to the ISO-OSI ModelApplication

Presentation

Session

Transport

Network

Data Link

PhysicalGatewayApplication

Presentation

Session

Transport

Network

Data Link

Physical

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