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Lecture 8Networking Fundamentals

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People use different types of networks every day:•Mail delivery system•Telephone system•Public transportation system

Networks are systems that are formed by links. Computers can be linked by networks

•Corporate computer network•The Internet

A network can be as simple as two computers connected by a single cable or as complex as hundreds of computers connected to devices that control the flow of information.

Principles of Networking

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Networking Roots PCs: Personal computers with:

Processor, memory, storageMade computing affordableDrawbacks:

Isolation of data, difficult to shareSecurity risks: Physical access granted access to data

Traditional, early mainframe environment:Dumb terminals Central mainframe computer

Networks: Primarily desktop PCs connected

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Why do we use networks? Generally for “connectivity”… The need to communicate with others Hardware resource sharing

e.g. printers, mapped drives Application sharing

e.g. administrative systems Group working

e.g. video conferences Backup and data security

e.g. duplicate data in separate physical location Remote configuration and management

e.g. technical staff can audit, fix and install software remotely Internet or intranet access

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Computer NetworksSome benefits from networking includes:• Fewer peripherals needed • Increased communication capabilities• Avoid file duplication and corruption• Lower cost licensing• Centralized administration• Conserve resources

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Basic ConceptsCommunications – activity associated with

distributing or exchanging informationTelecommunications – technology of communications

at a distance that permits information to be created any where and used everywhere with little delay

Today it, involves Data: digital and analogVoice: spoken wordVideo: telecommunication imaging

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Essentials for Communications

Must have a message

Message must have a transmitter/receiver

Message must have a medium

Message must be understood

Source Transmitter Transmission Receiver Destination

Source System Destination System

Workstation/PC Workstation/PCMedium

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The elements that make up a networkMessages

Information that travels over the medium

DevicesThese are used to communicate

with one anotherMedium

This is how the devices are connected together

Rules (Protocols)Govern how messages flow

across network

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Network ConcernsSecurity

Unauthorized access to resources and dataMaintenance and support

Data backupsManaging hardware and softwareReviewing and maintaining security

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The InternetStarted in 1969 as U.S. Department of Defense

ARPANETPlays key role in modern networking configurationsRoot source of many PC network innovations

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Types of Networks

A computer network is identified by:The type of media used to connect the devicesThe type of networking devices usedHow the resources are managedHow the network is organizedHow the data is storedThe area it serves

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Network ModelsTwo basic network models:

Client/serverOne or more computers designated as servers,

providing resources to networkProvides centralized control over network

securityPeer-to-peer

Network client computers act as both clients and servers (peer servers)

Smaller networks

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Data TransmissionSuccessful transmission of data depends on:

The quality of the signal being transmittedCharacteristics of the transmission medium

Data rate – bits per second in data communicationsBandwidth – bandwidth or signal is constrained by the

transmitter and the nature of the transmission in cycles per second or hertz

Noise – Average level of noise over the communication path.Error rate – rate at which errors occur where error in 1 or 0

bit occurs

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Basic transmission medium conceptsMedium is the physical path between transmitter

and receiver in a data transmission systemGuided Medium: waves are guided along a solid

medium path (twisted pair, coaxial cable, and optical fiber).

Unguided medium: waves are propagated through the atmosphere and inner/outerspace (satellite, laser, and wireless transmissions).

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Basic Signal Terminologies Bit: binary digit, either 0 or 1 Bit rate – a method for measuring data

transmission speed – bits per second Mbps – millions of bits per second (data speed;

measure of bandwidth = total information flow over a given time) on a telecommunication medium

8 bits = 1 byte Mb – million bits (quantity of data) MB – million bytes (quantity of data) Gbps – Billion bits per second (data speed) Teraflops – trillion operations per second

Kilo K 2^10Mega M 2^20Giga G 2^30Tera T 2^40Peta P 2^50Exa E 2^60Zetta Z 2^70Yotta Y 2^80

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Network Interface Card (NIC)Every computer and most devices (e.g. a network

printer) is connected to network through an NIC. In most desktop computers, this is an Ethernet card (10, 100 or 1000 Mbps) that is plugged into a slot on the computer motherboard.

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Network Interface Card (NIC)

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Wired NIC Connection to Network

There are two types of Ethernet cable.Standard Ethernet cable is used to

connect a network adapter to a hub/switch

Crossover cable is used to connect two PCs

Common in 100Mbps and 1Gbps, also available in 10Gbps

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Additional Functions of a NIC

Creates, sends, and receives framesFrame: fundamental unit of data for network

transmission and receptionDeals with frame-level errors and incomplete or

unintelligible frame structuresManages access to mediumActs as gatekeeper (permits inbound

communications aimed only at its computer (or broadcast) to pass through NIC and on to CPU)

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MAC Address

NIC has unique identifier, called Media Access Control (MAC) addressProgrammed into ROM chip48-bit number, written as six two-digit

hexadecimal numbersFirst part identifies manufacturerSecond part unique to each NIC

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Integrated NICs

On-board NICs: Most PC motherboard and laptop computer manufacturers integrate the network interface directly on to the motherboardMight not meet a user’s needs

Wrong media Wrong speedWrong architecture

Most on-board NICs are suitable for most users’ requirements

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Wireless Adapters

Include some or all of these components:Indoor antenna and antenna cableSoftware to enable adapter to work with

particular network environmentDiagnostic software to check installation or

troubleshootInstallation software

Used with wireless access point to add wireless devices to existing wired network