CHAPTER CHAPTER

Network HardwareNetwork Hardware

Chapter Objectives

• Describe the important basic network hardware and the internetworking hardware

• Discuss the desired characteristics of a server and a workstation

• Present different switching technologies

• Examine the routing process with the help of an example

Classification of Basic Network Hardware

Components• Network Interface Cards (NICs)• Cables• Connectors• Servers• Workstations

Classification of Internetworking Hardware

Components• Line drivers or repeaters• Transceivers• Intelligent hubs• Bridges• Switches• Routers • Gateways

Chapter Modules

• Network interface cards• Network connectors and hubs• Server and workstation hardware• Repeater• Bridge• Switch

Continued..

Continuation of Chapter Modules

• Switching technology• Router• Gateway

END OF CHAPTER END OF CHAPTER INTRODUCTIONINTRODUCTION

MODULE

Network Interface Cards (NICs)

Network Interface Card Types

• 10BaseT cards– Physical star networks– 10 Mbps speed– Ethernet standard– Twisted pair wiring

• 10base2 cards– Physical bus networks– 10 Mbps speed– Ethernet standard– Thin coaxial wiring

Continuation of NIC Types

• 10Base5– 10 Mbps speed– Ethernet standard– Thick coaxial wiring

• 100BaseTX– 100 Mbps speed– Fast Ethernet standard– Twisted pair

• Higher quality Category 5 wires are recommended

Token Ring Cards

• Token ring network cards• Earlier token ring cards

– 4 Mbps

• Newer token ring cards– 16 Mbps

Bus Types for NICs

• Card connector types– Newer PCI bus – Older ISA, VESA and EISA bus types

• ISA bus width– 16-bit

• PCI bus width– Usually 32-bit– Supports 64-bit as well

• Used in high-powered network servers

Cable Connections for NICs

• BNC barrel connector– Thin coaxial

• RJ 45– Twisted pair

AUI and Combo Cable Connections for NICs

• AUI Possibilities– Designed for a thick coaxial cable– Designed for a token ring network– Provided for connecting a transceiver

• Combo Cards– Consisting of different ports– BNC, RJ-45, AUI

Possible Combo Card Connections

• Thin coaxial cables (BNC)• Twisted pair wires (RJ-45)• Thick coaxial cables (AUI)

Description of an Actual NIC

• 10BaseT, PCI card– 10 = speed in Mbps– Base =Ethernet– T = Twisted pair– 32-bit = bus width– PCI = bus technology

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MODULE

Sample Network Interface Cards

Example of a 10Base2 Card

BNC

Source: Black Box

Example of a 10BaseT Card

RJ 45

ISA

Source: Black Box

Example of a Combo Card

Combo

Source: Black Box

RJ 45

BNC

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MODULE

Network Connectors and Hubs

Simple Connectors

• T connectors – An interface between the NIC and the

cables

• Terminators– Used at both ends of a bus network

TerminatorT Connector

Example of T-Connector and Terminator

T Connector

TerminatorSource: Black Box

Connectors : Hubs

• Types– Active hub– Passive hub

• Passive hubs– Simply provides the physical and the

electrical connection for the network

• Active hubs– Has built-in intelligence– Some are manageable hubs

Connectors : Passive Hub

MAU

WS WS

Hub Connecting A Token-ring Network

WS

An Active Hub

Backbone

Man

ag

eab

l e H

ub

RemoteWorkstation

WS

WS

WSRemote Monitor

Active Hub

Hub Management Software

• Sophisticated• Monitor the network traffic through

each of the ports• Becoming popular• Standardized protocol for remote

management exists– SNMP (Simple Network Management

Protocol)

Example of a Hub Used in Ring Network

Source: Black Box

Example of Hubs Used in the Star Network

StackableHubs

Source: Black Box

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MODULE

Server and Workstation Hardware

Module Objectives

• Give an overview of the different types of the server hardware

• Discuss the desired characteristics of a server

• Provide a specification for a workstation

Servers• Backbone of a network• Types

– Powerful micros– Servers– Super-servers– Sometimes mini-computers are used as servers

• In a client-server, the server also acts as an engine of database execution

• In general, it is used for the sharing of stored data and application

Desired Characteristics of Server: Processor and Storage Requirement

• Powerful processor– Latest Pentium Processor– Multiple processors, if appropriate

• Large storage space– Several gigabytes at a minimum– Actual requirement will vary LAN size

• Fast disk access speed – Less than 10 ms

Desired Characteristics of a Server: CD-ROM

• Fast CD-ROM drives• CD-ROM towers are often preferred

Desired Characteristics of Server: Storage

Technology• Better hard disk technology

– SCSI• Fast access• Daisy chaining of devices

– Latest SCSI technology is required

• Possible consideration given to fiber-channel in the future

Desired Characteristics of Server: Bus and Memory

Technologies

• Better bus technology– PCI

• Memory– In excess of 128 Mbytes– SDRAM or similar memory technology

functioning at 10 nanoseconds or less– The 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 facilities– Back-up tape

• Uniterruptible Power Supply (UPS)

Fault Tolerant Feature for Servers

• RAID storage technology– A system based on multiple disk– Hot-swappable disks

• Redundant power supply– Hot-swappable power supply

Workstation

• Most applications are executed at the workstation

• Therefore, it must be powerful in terms of the processor and the memory

• As 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 Memory

• Powerful processor– Pentium class processor

• Adequate memory – 32 Mbytes or more– DIMM preferred although fast EDO

SIMM may also be used

Workstation Storage and Compatibility

• Sufficient storage– Storage in gigabytes– Important in a client-server environment– Front-end tools are stored on the workstation

• Speed of storage– Ultra DMA or SCSI preferred – EIDE may also be used

• Hardware components with appropriate drivers for the client operating system

Reliability

• Power surge protector• Uninterruptible Power Supply

(UPS), for critical applications

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MODULE

Repeater

An Overview of Repeaters

• Used for extending the physical span of a network– An example is the extension of the

distance between a hub and a node

• Span is often limited by design considerations

• 10base5 – The span is limited to 500 meters

A Repeater Connection

Expanding 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 Model

• Operates at the lower level of the ISO OSI model– Physical layer

Medium

PhysicalLayer

Repeater

Medium

Physical Layer

Other Devices Used for Extending the Span of a

Network

• Line Drivers• Short-Haul Modems

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MODULE

Bridge

An Overview of a Bridge

• A device used for connecting two LANs operating under the same protocol

• Currently, the term bridge is loosely being used to describe different interconnecting devices– Used now for connecting LANs operating

under different protocols as well

Purpose of a Bridge

• Facilitate the movement of data packet from one network segment to another

• Not a sophisticated internetworking device

• Bridge does not perform the routing of information to different segments of a network

• Connects two network segments and not multiple network segments

Bridge

Bridge : ISO-OSI Layer of Operation

X Medium X Medium

Physical Layer

PhysicalLayer

DataLink

Layer

DataLink Layer

A simple bridge operates at the second layer of the ISO model.

Practical Bridge Implementations

• Local Bridge• Remote Bridge

Local and Remote Bridges

• Local bridge– Connects two different LANs located

locally

• Remote bridge– Connects LAN segments that are

geographically apart– An example is a device that provide

dial-up access to a LAN

A Practical Bridge Example

Source: Black Box

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MODULE

Switch

Switch Definition and Purpose

• A 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 Bridge

• A switch focuses on segmenting a LAN

• A bridge is concerned with linking two network segments that operate under different protocols

Purpose of a Switch

• Improve the network performance and reliability

• Better manage the network in general

Performance Improvement in Segmented Networks

• Performance is improved especially in the case of a bus network

• Multiple bus paths are now available for communication

• Each segment can engage in simultaneous communication within itself

• Easier to isolate a problem to a segment– Thus, better manage the entire network

Network Reliability

• When one segment does not function, the other segments can continue to function– Offers better reliability to at least part

of the function

Switches in Ethernet and Token Ring LANs

• Switches were originally designed for segmenting Ethernet LANs– Used extensively in configuring large

Ethernet bus LANs• Physically 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 Segments

Switch

Hub Hub

WS Server WS Server

Segment 1 Segment 2

Crossover Traffic

Using A Switch to Link Bus LAN Segments

Switch

Segment 1 Segment 2

Use of Switches in Internetworking

• Because the typical inter-networking connection involves multiple segments, the use of a switch is more common than the use of a bridge

WS

Use of Switches for Higher Bandwidth

100 MBps Switch

WS WS WS

Each port in theory has a bandwidth of 100 Mbps.

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MODULE

Switching Technology

Module Objectives

• Explain the basic operation of a switch

• List the switching technologies and describe their operation– Cut-through and store-and-forward

technologies

The Basic Operation of Switches

• A data packet is analyzed• Receiver’s addresses is checked• If it indicates the receiver to be in the

same segment, the packet is dropped• If it indicates the receiver to be in a

different segment, the packet is forwarded to a different segment

Receiver’s Address Sender’s Address Data

Switching Technologies

• There are two major types of switching technologies– Cut-through– Store-and-forward

Cut-Through Technology

• Reads only part of the packet– The addresses header– Packet is forwarded accordingly

• Bad packets are not filtered

Store-and-Forward Technology

• Entire packet is processed• Packets are filtered

– Bad packets are filtered

Switching Technology Comparison

Header Sender’s Add Receivers Add Data

Cut-through

Store-and-forward

Switching Technology Operation at the ISO Layer

• In each of the two cases of switching technologies no protocol conversion takes place

• Forwarding and filtering are done at the MAC layer

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MODULE

Routers

The Purpose of a Router

• Connect LANs operating under different protocols

• The LANs connected are better known as sub-networks instead of network segments– The term segments is nevertheless

used in practice

Router Characteristics

• A router true internetworking device– Connects different sub-networks together

• Establishes a logical path of communication between the sub-networks

• Contributes to the modular construction of a network– Network itself is better managed– Network resources are better utilized

Internetworking with a Router

IEEE 802.3Sub-network IEEE 802.5

Sub-network

PC-NFSSub-network

Router

Routers, Switches and Hubs in Perspective

Switch Switch

HubHub

S WS WSWS

Router

Hub

S WS

Hub

WSS

Hub

WSWS

Hub

WSS

Sub-network 1 Sub-network 2

Backbone

Difference Between Routers, Switches and

Hubs• Hubs

– Simply provides the mechanical and electrical connections between the nodes

• Switches– Examine the data packet for the destination

address– Do not alter the data packets

• Routers– Examine and alter the data packets– Perform protocol conversion

Router Requirements

• Requires more processing power compared to switches and bridges

• Operations fall within the network layer of the ISO-OSI communication model

Router : Network Layer Interface

X MEDIUM X MEDIUM

PHYSICAL LAYER

PHYSICALLAYER

DATA LINKLAYER

DATA LINKLAYER

NETWORKLAYER

ROUTERNETWORK

LAYER

Devices and Layers

PHYSICAL LAYER

DATA LINKLAYER

NETWORKLAYER

Switches

Routers

Repeaters

Sw

itch

es

Layer 1

Layer 2

Layer 3

A Practical Router Example

Router

Router

Router

Router

Router

Source: Black Box

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MODULE

Gateway

An Introduction to Gateways

• Gateways are comprehensive internetworking devices

• They can be computers themselves

Gateways in the Past

• Very popular• They were the only devices that could

be used for internetworking• Computers of the past were not

designed with network connections in mind– Interconnection of different computer

systems has to be managed and driven by an advanced device such as a gateway

The Present Scenario

• Computers are now designed with due consideration given to network connections

• Larger networks could today be configured using internetworking devices – Routers, switches, hubs etc.

Use of Gateways at Present

• Used in the rare occasion when neither of the internetworking devices could be used for connecting the sub-networks together

• Example– Connection of a legacy mainframe

system to a bus LAN

Rule of Thump

• Gateways are used for interconnecting vastly differing computing environments together

SNA Gateway

SNA Gateway

WS WS

Main

fram

e

LAN - Ethernet

IBM - SNA

FEPNIC Card

Gateway software

GatewayInterface

Card

Gateway’s Functional Relationship to the ISO-OSI

ModelApplication

Presentation

Session

Transport

Network

Data Link

Physical

Gateway

Application

Presentation

Session

Transport

Network

Data Link

Physical

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END OF CHAPTER END OF CHAPTER