Download - 71786243 Networking Basics


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Covers a small area Connects computers and workstations covering a

local area like, office or home


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Advantages of LAN: Improves productivity due to faster work

Provides easy maintenance

New systems can be installed and configuredeasily

Disadvantages of LAN:

Limited number of systems can only be connected

Cannot cover large area

Network performance degrades as number of

users exceeds


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LAN Types

Ethernet Token Ring Token Bus FDDI

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LANs are classified depending on the techniquesused for data sharing


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Made up of multiple LANs within limited area Connects different LANs in a campus


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Interconnects networks within a city

Supports data and voice transmission

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Covers a wide geographical area which includesmultiple computers or LANs e.g. Internet

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Consists of two elements, Client and Server Server:

A centralized element which provides resources to

client

Manages data, printers or network traffic

Client:

Manages local resources used by users such as

monitor, keyboard, CPU and peripherals


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Also known as ISO-OSI Reference Model

Developed by International Organization for

Standardization (ISO) Describes flow of information from one computer to

another

Consists of seven layers


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Topology refers to physical or logicalarrangement of network

Physical topologies are

Single Node

Bus Star

Ring

Mesh

Tree Hybrid

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Single device, at times device called dumbterminal is connected to the server

Devices operates on files from server andreturns them back after completing task

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Disadvantages:

Network consists ofsingle device

Dumb terminal isdependent on server

Advantages:

Easy to install,configure and manage

Least expensive

Single cable isrequired


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All devices are connected to a common cablecalled trunk Maximum segment length of cable is 200 m Maximum of 30 devices per segment


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Server is at one end and devices are at differentpositions

50 ohm terminator is used

Devices are not responsible for datatransmission

Number of collisions are more

Usually uses Thinnet or Thicknet

Performance degrades as more computers areadded to the bus.


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Advantages:

Installation ofdevices is easy

Requires less cablecompared to startopology

Less expensive andworks better forsmaller networks

Disadvantages:

If backbone breaks,entire network getsdown

Difficult to isolateproblems

Limited number ofdevices


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Each device is connected to a central device called hubthrough cable

Data passes through hub before reaching destination

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Advantages:

Easy to install,configure, manageand expand

Centralizedmanagement

Addition or removalof device does notaffect the wholenetwork

Disadvantages:

Requires more cable

Failure of hub affectsentire network More Expensive

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Advantages:

Data travels atgreater speed

No collisions

Handles largevolume of traffic

Disadvantages:

More cabling isrequired compared

to bus

One faulty deviceaffects the entirenetwork

Addition of devicesaffect network

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Consists of twoindependent primaryand secondary rings

Secondary ring isredundant, used onlywhen primary stops

functioning

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Used in WANs tointerconnect LANs

Every device isconnected to everyother device

Use routers todetermine the best

path ofcommunication

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Full mesh topology All devices are connectedto each other

Partial mesh topology - Some devices areconnected to only those with whom theyexchange most of the data

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Types

Full mesh Partial mesh


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Advantages:

Improves faulttolerance

Failure of one linkdoes not affect entirenetwork

Centralizedmanagement is notrequired

Disadvantages:

Difficult to installand manage

Each link from onedevice to otherrequires individual

NIC

Very much expensive

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Connects groups ofstar networks

Devices are wired toroot hub

Root hub isconnected to secondlevel devices

Lowest level devicesare smallercomputers

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Advantages:

Easy to add newdevices

Point-to-point

wiring for eachdevice

Fault detection iseasy

Disadvantages:

Difficult to configure

If backbone breaks,entire network goes

down More expensive

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Combines two or more different physical

topologies Commonly Star-Bus or Star-Ring

Star-Ring uses Multistation Access Unit (MAU)

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Advantages:

Used for creatinglarger networks

Handles largevolume of traffic

Fault detection iseasy

Disadvantages:

Installation andconfiguration is

difficult

More expensive thanother topologies

More cabling isrequired

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Segment Length Length of single wire Attenuation Indicates loss of signal

Bandwidth Amount of data carried by cable

Number of Segments Maximum number of

segments in network Cost Copper cables are cheapest, fiber optic

cables are expensive

Interference susceptibility and crosstalk Defines concept of electronic interference oncables

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Copper medium is the cheapest mode of data transfer

Types of cables

Coaxial cable Twisted pair cables

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Consist of a solid copper core surrounded by

an insulator mainly made up of Poly VinylChloride (PVC) or Teflon

Coaxial cables are less prone to interference(both internal and external)

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Coaxial cables are mainly divided intofour categories

Types of

Coaxial cables

RG58 RG8 RG6 RG59

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Maximum segment length is 200 (185) meters Interference protection is better than twisted

pair cables

BNC-T connector is used to connect this cable

Used in thinnet (10BASE2) network

Mostly used in changing environments

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Maximum segment length is 500 meters Interference protection is good compared to

any copper cable

BNC-T or Vampire Tap connector is used to

connect this cable Used in 10BASE5 network

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Broadband quad-shielded cable

Provides lowerattenuationcharacteristics

Useful in cable TV,CCTV and satellite dishantenna

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Solid conductor issurrounded by afoam polyethylenedielectric

Useful in securitycamera, cable TV andhome theatre

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A pair of cables twisted around each other forms a

twisted pair cable.

Twisted Pair cables

UnshieldedTwisted Pair

ShieldedTwisted pair

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Pair of unshielded wireswound around eachother

Easily gets affected byEMI, RFI and crosstalk

Maximum segment

length is 100 meters

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Cat 7

Cat 6

Cat 5eCat 5

Cat 4

Cat 3

Cat 2

Cat 1

UTP

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Pair of wires woundaround each other isplaced inside shield

Better protectionfrom EMI, RFI andcrosstalk ascompared to UTP

Maximum segmentlength of 100 meters

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Consists of centre glass core surrounded bycladding

Electrical signals are converted into light signals

LED or laser is used to transmit signal

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Bandwidth Carries large amount of dataranging from 100 Mbps to 1 Gbps

Segment Length Transmits data signals overlarger distance

Interference No electric signals pass throughthese types of cables thus providing security

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Fiber optic cables can carry signals in asingle direction.

Fiber Optic Cable

Types

Single Mode Multi mode

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A type of cable that has only a single strandof glass fiber with a thin diameter. Fiber optic cables that use lasers are known

as single mode cable.

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A type of cable that contains a glass fiber witha larger diameter.

It is a 62.5/125 micrometer fiber cable.

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Straight Tip (ST) Joins individual fibers tooptical devices

Subscriber Connector (SC) Attaches two fibersto send and receive signals

Medium Interface Connector (MIC) Joins fiberto FDDI controller

Sub Miniature Type A (SMA) Uses individualconnectors for each fiber stand

Fiber Jack Attaches two fibers in snap lockconnector

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Characteristics UTP STP Coaxial Cables Fiber Optic Cables

Bandwidth 10 Mbps100 Mbps 10 Mbps100 Mbps 10 Mbps 100 Mbps - 1 Gbps

Maximum cable segment 100 meters 100 meters 200500 meters 2 k.m.100 k.m.

Interference rating Poor Better than UTP Better than twisted pairwires

Very good as comparedto any other cable

Installation cost Cheap Costly than UTP Costly than twisted pair

wires

Most costly to install

Bend radius 360 degrees / feet 360 degrees / feet 360 degrees / feet or 30

degrees / feet

30 degrees / feet

Security Low Low Low High

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Networking devices interconnects networks Manage data flow and network traffic

Networking

Devices

Repeaters Hubs Bridges Switches Routers GatewaysOther

Devices

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Operate at Physical Layer of the OSI model

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Reshape the weak signal

Connect two segments of the same LAN


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Simplest and low cost device Also known as Multi-port Repeater

Operate at Physical Layer like Repeater

Data transfer to all the ports

Hub types:

Active hub Provides signal regeneration

Passive hub No signal regeneration

Intelligent hub

Provides management of each port


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Layer 2 devicesas works at Data

Link Layer of the

OSI model

Interconnectmultiple LANs

and manages

data flow


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Working of a bridge


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Capable of passing a frame

Check Physical address

Pass frame to the specified segment

Perform error checking on the frame

Bridges

Transparent

Bridge

Translational

Bridge

Source-route

Bridge

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Easy to use as just plug in device Helps in network expansion Divides large network into small segments Used for increasing network reliability

Frames are buffered so provides network delay During high traffic may overload network Does not filter broadcast packets Expensive than Repeaters

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Switching

Methods

Cut-through

Method

Store & Forward

Method

Fragment-Free

Method

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Provide signal flow management

Replace slower hub

Being a Data Link Layer device uses MAC address

for data transfer

Data transfer to specific port


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Operate at Network Layer of the OSI model

Can connect nearer or far network segments


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Decide the best route with the help of network layeraddress

Responsible for Source to Destination delivery of

packet

Route types: Static route Routing tables are manually configured

Dynamic route Routing tables are automatically

configured


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Helps routers to learn network topology and

network changes

Routing algorithms are used by routing protocols for

deciding the path


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Gateway

Types

Address

Gateway

Protocol

Gateway

Application

Gateway

Transport

Gateway

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Operate at all layers of the OSI model Act as gate to other networks

A default gateway is on the same subnet as your

computer


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OtherDevices

Multi-Protocol

RoutersBrouters

Layer 3

Switches

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Multi-protocol router supports multiplecommunication protocols

Like router, it operates at Network Layer


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Brouter provides combined functions of Bridge and

Router

Works at two layers, Data Link and Network

Can operate only as bridge or only as router

High performance switch operating at network layeris Layer 3 Switch


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Set of predefined rules used by devices innetwork for data transfer

Network Protocols: TCP/IP ARP/RARP ICMP/IGMP UDP IPX/SPX HDLC/SDLC

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Two layer communication protocol used byInternet

TCP provides connection-oriented reliabletransport service

Divides the message into smaller packets calledsegments

IP is a connectionless and unreliable datagramprotocol and provides no error checking

IP transfers data in the form of packets called

datagrams

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Designed beforeOSI model

Consists of fivelayers

Providesindependentprotocols at eachlayer

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Fragmentation refers to breaking datagramsinto pieces

Maximum Transfer Unit (MTU) is maximumamount of data that frame can carry

Datagram is fragmented when its size exceedsMTU of network

Fragments follow different paths to reachdestination

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To deliver packet both physical and logicaladdresses are necessary

Address Resolution Protocol (ARP) providesphysical address when logical address is known

Reverse Address Resolution Protocol (RARP)maps logical address to physical address

RARP is useful when device is booted for firsttime

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Internet Control Message Protocol (ICMP) provides

error reporting and query managementmechanism

ICMP handles problems occurring while packettransmission

Internet Group Message Protocol (IGMP) managesmulticasting and group membership of devices

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Error Reporting

Destination

Unreachable

Router Solicitation

and Advertisement

Timestamp request

and reply

Address Mask

Request and reply

Echo request

and reply

Query

Source Quench

Time Exceeded

Redirection

Parameter Problem

ICMP Messages


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User Datagram Protocol (UDP) providesconnectionless process-to-processcommunication

UDP packets are called user datagrams.

User Datagram Format:

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Novell NetWare system uses IPX/SPX ascommunication protocol within networks

IPX operates at Network layer forconnectionless communication

SPX operates at Transport layer for connection-oriented communication

Together, IPX/SPX provides same services asTCP/IP

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High Level Data Link Control (HDLC) andSynchronous Data Link Control (SDLC) are bit-oriented synchronous protocols in which dataframes are interpreted as series of bits

Both are useful for half-duplex and full-duplexcommunication

Windows XP still support DLC

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OSI Layers Protocols

Physical Layer No protocols defined

Data Link Layer HDLC, SDLC

Network Layer NetBEUI, IP, ICMP, IGMP, ARP, RARP, IPX

Transport Layer NetBEUI, TCP, UDP, SPX

Session Layer NetBIOS, SAP, SMTP, FTP, DNS, SNMP,

Presentation Layer NCP, RIP, NLSP, SMTP, FTP, DNS, SNMP, NFS

Application Layer SMTP, DNS, SNMP, NFS, TFTP

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Specifies how mail should be delivered fromone system to another

Standard protocol used for transferring emailfrom one computer to another

Makes connection between senders server andrecipient and then transfer messages

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A two-way transmission channel established between the

sender SMTP and a receiver SMTP

Commands are generated by sender SMTP and sent toreceiver SMTP

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Set of rules used to exchange files on WorldWide Web

Users can exchange text, graphic images,sound, video and other multimedia files

Defines how messages are formatted andtransmitted over the Internet

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HTTP works on requestand response betweenbrowser and server

Web server is designatedto handle HTTP requeststhen sends requestedHTML page

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Proxy servers is used with firewalls to monitor and

direct HTTP traffic through proxy to externalinternet

File Transfer Protocol (FTP)


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Used over Internet to exchange files Uses Internet's TCP/IP protocols to enable data

transfer

Establishes two way connections between

computers

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File Transfer Protocol (FTP)


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Machine that are involved in an FTP transaction Client (local host) machine and a server(remote host)

Client machine initiates transfer

Get command used tocopy files from server to

client

Put command is used to

copy files from client to server

Ch

apt

er

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Used to transfer files to and from a remotecomputer

Used by servers to boot diskless workstations,X-terminals and routers

Start with a small amount of built-in software

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Connection and Communication betweenClient/Server

Communication and messaging different in TFTPwhen compared with FTP

TFTP uses UDP Process of transferring a file:

Initial Connection

Data Transfer

Connection Termination

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Used to transfer Usenet news from onemachine to another machine

Usenet news is a large collection of discussiongroups, covering a wide range of topics

NNTP provides connection-oriented service Communication takes place between a client

and a server that keeps netnews on both theplaces

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Framework for managing devices over Internetusing TCP/IP protocol suite

Provides set of fundamental operation for

monitoring and maintaining devices in thenetwork

Agent is server process that maintainsManagement Information Base (MIB) database

for host

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Used to retrieve email from remote server tolocal client over TCP/IP connection

E-mail clients using POP3 connect, retrieve allmessages or store them on user's PC as newmessages or delete them from server and

disconnect POP3 is a TCP/IP client/server protocol Session States:

Authorization State

Transaction State Update State

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Enables the users to work with the mail on theserver

Does not download the mails

Used to access e-mails from a local server

Working with mails Accessing and deleting mails

Attachments

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Advantages: As the e-mail folders

are stored on theserver, the user isable to read email

from any computerwhich belongs to thenetwork

To access more thanone account fromdifferent locations,IMAP will be the mostefficiently

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Disadvantages: Complicated

Results in higher server

loads than POP3

Utilizes a lot of server

resources


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BOOTP First automated configuration tool for

IP hosts Bootstrapping Provides the host with the

capability of getting IP addresses while machineboots

Requires two phases: Client provided with address and other parameters

Client downloads softwares to function on network andperform tasks

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Dynamic Host Configuration Protocol (DHCP) Successor of BOOTP with different features

Dynamically assign addresses to clients andcentrally manage

Consists of two major components 1.Address allocation mechanism 2. Protocol thatallows clients and server to communicate

DHCP standard includes three different address

allocation mechanisms: Manual , Automatic and Dynamic

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Network protocol used on internet or local areanetwork connections

Terminal emulation program for TCP/IPnetworks

Enables to control server and communicatewith other servers on network

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Telnet client Software that acts as interface touser, processing user commands andpresenting output from remote machine

Telnet server - Program running on remotecomputer that has been set up to allow remote

session Telnet runs over connection-oriented TCP TCP connection maintained for duration of

Telnet session Client and server send information at same

time over Telnet session because TCP is a full-duplex

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WWW is a network of Internet servers, whichsupport documents that are developed usingHTML

Hyper Text Markup Language (HTML) is a

language in which these documents areformatted

Client-side

Computer application Web browser that runs on

users local computer and connects to server Interpreter that interprets code in an HTML page

Operations carried out on client-side

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Server Side Software program Web server that runs on a

remote server

Manages and shares web based applications

Operations include processing and storage ofdata from client to server

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Wireless networking allowsyou to establish: Communication using standard network

protocols

Communication without the use of

cables Technologies used for wireless access

based on

Wireless fidelity (Wi-Fi)

Home Radio Frequency

(HomeRF)


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Peer-to-Peer(P2P) or Ad-Hoc Connected wirelessly with the use of wireless

Network Interface Card (NIC)

Computers can access printers and share files

Wired LAN can be accessed using bridging

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Access point orInfrastructure wireless LAN

Wireless device connectsto the access point toconnect to the network

Access point acts as ahub to connect twowireless devices

Wireless bridge used toconnect wireless networkto wired network

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Security Four methods of wireless network security:

Data encryption - WEP (Wired Equivalent Privacy)and WPA (Wi-Fi Protected Access)

Port based access control Service Set Identifier (SSID)

Media Access Control (MAC) address filtering

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The important components required for settingup a wireless network are:

Medium

Access point and Extension point

Wireless bridges and Power line bridges Antennas

Wireless adapters

Wireless Station and Server

Software

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Wireless medium is an unguided form ofnetworking medium

Wireless transmission involves use of technologiessuch as Bluetooth, Infrared, Lasers, Radio signalsand Microwave technologies

Mobile computing allows users to do their work atany location

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Access Point Device that bridges a wireless connection and a

wired connection

Two types of access points: Hardware access

points and Software access points Extension Point

Used if single access point is not able to coverentire area

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Hardware access point is a physical device that

is used to establish a connection between awired network and a wireless network

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Software Access Points are computer whichincludes a wireless network interface card.

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Extension points are used if a single accesspoint is not able to cover the entire area.

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Antennas are used to increase the range ofwireless network

Types of antennas used: Omnidirectional antennas - Used indoors and

small in size Directional antennas - High gain and used for

long range outdoor use Wireless adapters help to connect computer or

PDA to a network Wireless adapters are available as PC cards, PCI

and mini PCI, USB, and CompactFlash.

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Wireless Local Area Network consists ofwireless station and wireless server

Wireless station - Connects wireless networkinto a wireless medium

Wireless Stations

Wireless Clients Access Points

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Wireless server The main server which controls

all devices within the wireless network


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Wireless network adapter requires two types ofsoftware so as to function properly:

Driver

Configuration Utility

Windows XP has built-in tools for configuringnetwork adapter settings