Chapter 12 - Networking

8/3/2019 Chapter 12 - Networking

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Networking

Chapter 12CXC Information Technology


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What is a Network?

A set of computers that are interconnected viasome medium.

Its primary purpose is to share resources andprovide a means of communication.

Each computer on the network is sometimesreferred to as a node.


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LAN Local Area Network Provide high-speed, fault tolerant data networks.

Covers a small area in a single or group ofbuildings.

Provide connected users with shared access to devices

Applications

Exchange files Communicate via email.


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WAN Wide Area Network

Cover broadergeographic areas

Uses transmissionfacilities provided bycommon carriers suchas telephonecompanies.

Interconnect a numberof LANs.


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Implementation

A NIC (networkinterface card)required

Enables eachcomputer tocommunicatewith the

network.


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Implementation

Various specialistnetwork hardware:

Act as connecting

points betweennodes

Example hubs andswitches.


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Implementation

Connection medium:

Wire or cable &wireless

connection.


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OSI ModelOpen Systems Interconnection

Developed by ISO(International Organization forStandardization)

Describes how informationmoves through a network.

Each layer performs aspecific function or task.

Layers are self-contained. Tasks can be implemented

independently.


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OSI (layers)Open Systems Interconnection

Upper layer:

Deals with application issues.

Implemented only in software.

Lower layer:

Handles data transport issues.

Physical and data link layers:

Implemented in hardware &software.

Other lower layers:

Implemented only in software.

Physical layer:

Network cabling places info onmedium


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Clients & Servers

It is important to establish the right network foryour organization.

There are two types of network:

Peer-to-Peer

Best for small networks

Security is non-existent

Client-Server Optimized to serve requests from clients.


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What is a server?

A dedicated machine thatserves a specific purpose.

They deal with requests

from other computersknown as clients.

Examples:

File server

Print server

Mail server etc.


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Benefits for using Servers

Optimization:

Designed to handle requests from clients.

Centralization: Files all in one location for easy administration.

Security

Multiple levels of permission for users.

Redundancy & Backup

Data stored in a redundant way for quick restore.


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Server hardware basics

Any normal desktop may work BUT more robustsystems are better. They should have:

Hot-swappable drives bays where drives can beinserted or replaced while the computer is

running. Support multiple processors.

Support large amounts of RAMs.

Faster input and output.

Fast network cards.

Redundant components to cut down on chance ofcomputer failing.


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Server software basics

They come in two categories:

Network Operating System (NOS)

Have file server, print server, backup & security

resources. Some may have web servers or mailservers

Examples: - Windows NT, 2000 and 2003; Linux;Novell Netware

Server Applications Software designed for many purposes.

Example: fax servers, remote access servers tc.

Must be able to run on NOS.


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Peer-to-Peer

A communication model that allows parties toinitiate communication sessions.

Each node may be given both serve and clientcapabilities.

On the Internet, this type of network allows groupof users with the same network program to

connect to each other. Napster and Gnutella are examples but are

synonymous of illegal sharing of files.


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Network Applications

Are software applications that require or benefitfrom the presence of a network.

Example: SQL Server, web based applicationssuch as Moodle.

You thus become reliant on you network.

Hence you need a well planned architecture for

your network.

Implementation of these is done throughfunctional modules such as:


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Communication module

If application works through a network, it musthave some means of communication.

It is important to consider issues that may arise

when applications scan multiple computers.


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Concurrent Usage module

This is what keeps one task distinct from another.

Must be able to maintain the integrity of the dataor process when different users want to modify

the same bit of information.

Network apps must be able to handle this alongwith multithreading and integrity.


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State Management

Defines where a process is for an application thatuses a network.

This is what is referred to as the state of the

process.

Single-user, standalone applications finds it easyto maintain this.

Multi-users have to maintain a set of data for eachuser.


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Latency

It is the amount of time it takes to communicateto other components on the network.

Network latency is how long it takes for the

application to communicate over the network. The communication has to go through routers,

switches etc that add latency to thecommunication.

The number of times a system need to call aremote server must be considered to maintainacceptable performance.


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Rigorous Encapsulation

Encapsulation a technique that hides orencapsulates details of some implementation fromthe software using the implementation.

Object oriented programming uses this method.

An application using an object has no idea howthe objects maintain the data or implements the

methods. One team have no idea who wrote the component

etc.


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Cabling & Configuration

CAT 5 cable available inreel-in-box

Has 4 twisted pairs of wire

Pairs are color coded onesolid color, the other withwhite background and astrip of the same color.

Colors are described usingthe background colorfollowed by stripe

eg. White-orange: whitebackground and orangestripe


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Straight-through & Cross-over

Straight-thru has identical ends.

Used in Ethernet connections.

Commonly known as patch cable.

Connect computers, and other end-user devices (eg. Printers) to networkdevices such as hubs and switches.

Cross-over has different ends.

Connects two like devices (eg. Hubsand switches) without the use of anuplink port (device that reverses the

transmit and receive circuitconnected to it) peer-to-peer

Has one end with orange switchedwith green set.


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CAT 5 RJ45 Modular Plug


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The Crimper

Has cutters to cut the cable and individual wires

May have striping and outer jacket.


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Making Cables

VIDEO

How to make a Cat5e Network/Ethernet Cable


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Cabling Rules 1

Avoid running cable parallel to power cables.

Don't bend cables less than four times thediameter of the cable.

Zip tie cable together, do not over-cinch them

Keep cables away from devices that introducenoise such as TV sets, microwaves, telephones

speakers etc.


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Cabling Rules 2

Avoid stretching UTP cables (UnshieldedTwisted Pair).

Do not run UTP cables outside building. It is a

very dangerous lightening hazard.

Use telephone wire/RG-6 coaxial cable to secureUTP cables.


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Network Configuration

Locate NetworkConnections inControl Panel.

Right-click on networkor LAN properties.

Select Internet

Protocols (TCP/IP) Enter values provided

by network admin.


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TCP/IP configuration

Default setting isDHCP-enabled (obtainIP address

automatically) If necessary, enter

fixed IP address,subnet mask, default

gateway

Click OK


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Joining a Domain


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TCP/IP

Transmission Control Protocol/Internet Protocol

Communication language of the Internet.

Uses client/server model of communication. It is primarily point-to-point or host-to-computer.

Has 2 layers:

Higher layer Lower layer


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Higher Layer (TCP)

Manages the assembling of a message or file intosmaller packets.

Packets are transmitted over the Internet.

They are received by the TCP layer and themreassembled into the original message


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Lower Layer (IP)

Handles the address part of each packets.

This ensures it gets to the right destination.


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Higher Layer Application Protocols

These use TCP/IP to get to the Internet:

HTTP: Hyper Text Transfer Protocol

FTP: File Transfer Protocol

Telnet: lets you login to remote computers

SMTP: Simple Mail Transfer Protocol

These are packaged along with the TCP/IP suite.


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Related Protocols

These include:

UDP: User Datagram Protocol (used instead ofTCP for special purposes)

Protocols used by networks to exchange routerinformation:

ICMP: Internet Control Message Protocol

IGP: Interior Gateway Protocol EGP: Exterior Gateway Protocol

BGP: Border Gateway Protocol

Chapter 12 - Networking

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