Netwoking Note

8/2/2019 Netwoking Note

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NETWORKING CONCEPTS

BY-SANTOSH B. SINGH

**** (Follow the text book for detailed information) ****

FULL FORMS:-

AM : Amplitude Modulation

ATM : Asynchronous Transfer ModeCDM

A : Code Division Multiple Access

DGM : Data Grade MediumDHT

ML : Dynamic HTML

EDGE : Enhanced Data rates for Global Evolution

FM : Frequency Modulation

FTP : File Transfer Protocol

GHz : Gigahertz ( represents a thousand MHz)

GSM : Global System for Mobile

HTML : Hypertext Mark up Language

HTTP : Hypertext Transfer Protocol

IDEN : Integrated Digital Enhanced Network

IPCP : IP control Protocol

kbps : Kilo bits per second. ( small k)

Kbps : Kilo bytes per second. ( Capital K)

KHz

: Kilohertz ( represents thousand cycles per

second)

LAN : Local Area Network

LCP : Link Control Protocol

MAC : Media Access Control

MAN : Metropolitan Area Network

mbps : Mega bits per second. ( Small m)

Mbps : Mega Bytes per second. (Capital M)

MHz : Megahertz ( represents a thousand kHz)

NCP :Network control ProtocolNFS : Network File System

NIC : Network Interface Card

NIU : Network Interface Unit

PM : Phase Modulation

PPP : Point to Point Protocols

SIM : Subscriber Identification Module

SLIP : Serial Line Internet Protocol


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SMS : Short Message Service

SMTP : Simple Mail Transfer Protocol

STP : Shielded Twisted Pair CableTCP/I

P

: Transmission Control Protocol / Internet

Protocol

TDM : Time division multiplexing

TDM

A : Time Division Multiple Access

THz : Terahertz ( represents a thousand GHz )

URL : Uniform Resource Locator

UTP : Unshielded Twisted Pair Cable

VGM : Voice Grade Medium

WAN : Wide Area Network

WLL : Wireless in Local LoopWW

W : World Wide Web

XML : Extensible Markup Language

Short Notes:

Gate way: In Internet most computers are not connected directly to the Internet. Ratherthey are connected to smaller networks (LAN), which in tern are connectedthrough gateways to the internet back bone. So it is a device that connectsdissimilar networks.

Bandwidth:The difference between the highest and the lowest frequencies allowed on atransmission medias called its bandwidth

.Back bone: A back bone network is a network that is used as a backbone to connect

several LANs together to form a WAN.

TCP/IP The TCP part is responsible for dividing the file/message into packets (themessage or the file/document to be sent to another computer isfirstly divided into very small parts called Packets) on the sourcecomputer and also responsible for reassembling the received packets at thedestination or recipient computer. Where as IP is responsible for handling theaddress of destination computer so that each packet routed (sent) to itsproper destination.

Interspace It is the client/ server software program that allows multiple users to

communicate online with real-time audio, video and text chat in dynamic 3denvironments.

Server The computer which facilitates the sharing of data, software, and hardwareresources on the network.

There are two types of servers are there, they are :

i) Non dedicated server:- The computer which is not completely dedicatedto the cause of serving , used in a small networks and can facilitatethe resource-sharing.


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ii) Dedicated server:- The computer which is reserved for serving job andits only job is to help workstations access data, software and hardwareresources, it is used on a bigger network.

Circuit Switching In this technique, first the complete physical connection between twocomputers is established and then data are transmitted from the source

computer to the destination computer, for which it can be called asconnection oriented transmission.

Message Switching In this case the source computer sends data or the message tothe switching office first, which stores the data in it buffer, then looks fora free link to another switching office and then sends the data to thisoffice.

Packet Switching In this case a fixed size of packet which can be transmitted across thenetwork is specified. Another difference from message switching is thatdata packets are stored on the disk in message switching whereas inpacket switching, all the packets of fixed size are stored in mainmemory. This can also be called as connectionless transmission.

COOKIES Cookies are messages that a web server transmits to a web browser sothat the web server can keep track of the users activity on a specificweb site.

HACKERS & CRACKERS The Crackers are the malicious programmers who break intosecure systems whereas Hackers are more interested in gainingknowledge about computer systems and possibly using this knowledgefor playful pranks.

Firewall The system designed to prevent unauthorized access to or from aprivate network is called a firewall.

Network security It refers to making efforts to make sure that only legal or authorizedusers and programs gain access to network or network resources.

Cyber Law It is a generic term which refers to all the legal and regulatory aspects ofInternet and the World Wide Web. Anything concerned with or related toor emanating from any legal aspects or issues concerning any activity ofnetizens and others, in cyberspace comes within the ambit of Cyber law.

Web Hosting Web hosting is a means of hosting web-server applications on acomputer system through which electronic content on the Internet isreadily available to any web browser client.

GSM &CDMA GSM communications is a technique that uses narrowband TDMA, which

allows eight simultaneous calls on the same radio frequency. CDMA onthe other hand, unlike GSM, does not assign a specific frequency to eachuser. CDMA uses spread-spectrum technique where every channel usesfull available spectrum. With CDMA, data is sent in small pieces over anumber of discrete frequencies available for use at any time in thespecified range.

NETWORK DEVICES


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BRIDGLAN-LAN-

MODEM It is a computer peripheral that allows us to connect and communicatewith other computers via telephone line. Its work is to modulating/demodulating the signals, means convert the digital signal to analogsignal and vice versa.

HUB It is a device used to connect several computers together. It containsmultiple independent but connected modules of network and inter-

networked equipment. ( It is a multiport repeater).

SWITCH It is a device that is used to segment networks into different sub-networks called subnets or LAN segment. A switch is responsible forfiltering, i.e. transforming data in a specific way and for forwardingpackets between LAN segments. ( It is a multiport bridge).

REPEATER A repeater is a network device that amplifies and restores signals forlong-distance transmission.

BRIGDE It is a network device that establishes an intelligent connection betweentwo local networks with the same standard but with different types ofcables, means it is smart enough to know which computers are on which

side of the bridge, so they only allow those messages that need to get tothe other side to cross the bridge.

ROUTER It is a network device that is used to separate differentsegments in a network to improve performance and reliability. A routerworks like a bridge but can handle different protocols.

The main difference between bridge and router is :- bridge uses logicaladdresses where as the router uses physical addresses.

GATEWAY It is a network device that connects dissimilar networks. It establishes an

intelligent connection between a local network and external networkswith completely different structures.

CHECK LIST FOR NETWORK COMPONENTS (KNOW HOW TOCONNECT COMPUTERS)

For a building a small LAN

Clients computers with NICs installed

Server

Hub

Cabling


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For connecting offices and Departments

Clients with NICs installed

Servers

Hubs

Switch

Cabling

Router for shared internets access ( optional)

For connecting dispersed office sites

Clients with NICs installed

Servers

Hubs

Switches

Routers at each location for WAN connections/ shared internetaccess

Access server for dialup access for remote users

Cabling

WAN services(ISDN / leased line etc.)

ADVANTAGES & DISADVANTAGES

Twisted Pair Cable

Advantages

Easy to install and maintain

Physically flexible

Low weight and very inexpensive

Easily connected

Disadvantages

It is incapable carrying a signal over long distances.

Low bandwidth for which it is unsuitable for broadband applications.

Coaxial Cable


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Advantages

Used for broadband transmission

Higher bandwidth.

Disadvantages

Expensive as compared to twisted pair cable

It is not compatible with twisted pair cable

Optical Fibers

Advantages

It is immune to electrical and magnetic interference i.e. noise in anyform is travelling on . a modulated

light beam.

It guarantees secure transmission and has a very high transmission capacity.

It can be used for broadband transmission.

Disadvantages

Installation problem

These are more difficult to solder

These are the most expensive of all the cables.

Micro wave

Advantage:

It offers ease of communication over difficult terrain

Microwaves have the ability to communicate over oceans

Disadvantages:

Insecure

Signal strength may be reduced

Weather effective

Bandwidth allocation is limited

The cost of design, implementation is high.

Radio Wave

Advantages


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Offers mobility

Ease of communication over difficult terrain.

Disadvantages

Insecure communication

Weather effective

Satellite

Advantages

Area coverage through this transmission is quite large.

Can cover large areas of the earth.

Disadvantages

Technological limitations

Over crowding

The investment cost is high

Star Topology

Advantages

Ease of service

One device per connection

Centralized control

Simple access protocols

Disadvantages

Long cable length

Difficult to expand

Central node dependency

Bus topology

Advantages

Short cable length

Resilient architecture

Easy to extend

Disadvantages


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Fault diagnosis is difficult

Fault isolation is difficult

Repeater configuration

Ring or Circular Topology

Advantages

Short cable length

No wiring closet space required

Disadvantages

Node failure causes network failure

Difficult to diagnose faults

Network reconfiguration is difficult

Tree Topology

Advantages

Simulates hierarchical flow of data

Easy to extend

Disadvantages

Long cable length

Root dependency

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