COMPUTER NETWORK

What is network?

  • A network is a collection of computers, servers, mainframes, network devices, peripherals, or other devices connected to one another to allow the sharing of data. An excellent example of a network is the Internet, which connects millions of people all over the world. Below is an example image of a home network with multiple computers and other network devices all connected to each other and the Internet.
Cmmunication Device & Transmission Media

 Communication Devices :
  • A communication device is any type of hardware capable of transmitting data,instructions and information between a sending device and a receiving device.
Type of communication devices :


  • Dial-up Modem - can convert digital signals to analog signals,so that data can travel along an analog telephone line.
  • Digital Modem (ISDN,DSL,Cable Modem) - sends and receives data and information to and from a digital line.
  • Wireless Modem - some mobile users have a wireless modem that uses the cell phone network to connect to the internet wirelessly from a notebook computer,a smart phone or other mobile devices.
  • Network Card - enables the computer or devices that does not have built in networking capability to access a network.
  • Wireless Access Point - A central communication device that allows computer and devices to transfer data wirelessly.
  • Router - connects multiple computers or other routers together and transmits data to its correct destination on a network.
  • Switch - similar to a hub but more sophisticated including functionality tha alow it to control and manage data transmissions.
  • Hub - allows multiple conection to  the network.

Router

Hub 





Dial up modem



Switch
Transmission Media : 
  • Materials or substances capables of carrying one or more signals in a communications channel.

Physical Transmission :




Type
Description
Twisted Pair Cable
  •         Consists of one or more twisted-pair wires bundled together.
  •            Widely used transmission media for network cabling and telephone system.
Coaxial Cable
Consist of a single copper wire surrounded by at least three layers:
  1.        An insulating material
  2.        A woven or braided metal
  3.        A plastic outer coating.
Fiber Optic
           A transmission media that uses glass or plastic fiber to carry light (laser) signals.

Wireless Transmission Media :

Type
Description
Microwave
Provide a high speed signal transmssion:
*Microwave transmission,often called fixed wireless,involves sending signals from one mocrowave station to others.
Communication Satelite
A space station that receives microwave signals from an earth based station,amplifies the signals,and broadcast the signal back over a wide artea to any number of eath based stations.
Infrared
A wireless transmission medium that sends  the signals using infrared light waves.
Broadcast Radio (Bluetooth,ultra Wideband (UWB),Wi-Fi,WiMAX)
Disributea a radio signals through the air over long distances such as between cities,regions and coutries and short distances such as within an office or home.
Cellular Radio (2G,3G,4G)
A form of broadcast radio that is used widely for mobile communications,specifically wireless modems and cell phones.

Advantages of Network :

Easy communiccation and speed
  • People can communicate efficiently by using network such as emails,instant messaging,telephone,video conferencing,chat room.etc.
Ability to share files,data and information
  • It can benefit large organizations to maintain their data in an organized manner and facilities access for desired people.
Sharing hardware
  • Can reduce the cost of purchasing hardware.
Sharing software
  • Can reduce the cost of buying software by networking their computers because networkable versions of software are available.
Security 
  • Sensitive files and programs on a network can be password protected and can only be accessed by the authorized users.
Speed
  • Sharing and transferring file within networks is very rapid,depending on the type of network.This will save time while maintaining the integrity of files.

 Disadvantages of Network :

Breakdown and possible loss of resources
  • Breakdown of the whole network due to ana issue of the server may lead to loss of important data of the server.
Expensive to build
  • Building a network for large scale organizations are very pricey ecpecially to buy and replace cables and other hardware.
Security threats
  • There are hackers who are trying to steal valueable data of large companies for their own benefit.
Bandwidth Issues
  • Heavy users who consume a lot more bandwidth will affect other users.
















Comments

Post a Comment

Popular posts from this blog

NETWORK ARCHITECHTURE

Image
NETWORK ARCHITECTURE Definition  : The configuration of computers,devices and media on a network. Client-Server network Peer to peer Network Differences Between Client/Server and Peer to Peer Network Category Client/Server Peer-to-Peer Definition One or more computers act as a server and the other computers on the network request services from the server. Each computer called a peer,has equal responsibilities and capabilities,sharing hardware (such as a printer),data or information with other computers on the peer-to-peer network. Size For medium and large network. For small network fewer than 10 computers. Operating System Needs a specific operating system such as Windows Server 2008. Does not need a specific operating system. Training Need training. Does no need training. Set up More difficult to set up. Easy to set up. Installation More expensive to install. Less expensive to install. Implementation
Read more

INTERNET SERVICES

Image
INTERNET SERVICES Types of Internet Services : World Wide Web (WWW) E-Mail Instant Messaging Voice over Internet Protocol (VoIP) Message Board File Transfer Protocol WORLD WIDE WEB (WWW) -Consist of a worldwide collection of electronic documents.Each electronic document called web page which can contain text,graphic,animation,audio and video.Have built in conections to other documents. Static (fixed) - visitor see all the same content. Dynamic - visitor can customize some or all of the viewed content such as desired stock quotes,weather for a region or ticket availability for flights. E-MAIL -Short for electronic mail. -Transmission of messages and files via a computer network.Consist of simple text or can contain attachment such as documents,graphics,audio or video clips. -Google and Yahoo! provide free e -mail services. -An e-mail address is a unique name that consist of a user name and domain name that identifies the user. -Basic form : username@host
Read more

RULES OF NETIQUETTE

Image
RULES OF NETIQUETTE Netiquette or net etiquette (etiquette on the Internet ) Is the code of acceptable behaviours users should follow while on the Internet or online cyberspace. It is conduct expexted of individuals while online. For : WWW,E-mail,Instant Messaging,Chat room,Newsgroup & message board. Image 1 NETIQUETTE GUIDELINES FOR ONLINE COMMUNICATIONS  Image 2 Golden Rule : Treat others a you would the to treat you. Be polite.Avoid offensive language. Avoid sending or posting flames,which are abusive or insulting messages.Do not participae in flame wars,which are exchanges of flames. Be careful when using sarcsm and humor,as it migh tbe misinterpreted. Do not use all captal letters,which equivalent of SHOUTING! Use emoticons to express emotion. Clearly identify spoiler,which is a message that reveals an outcome to a game or ending to a movie or program. Be forgiving of other's mistakes. Read the FAQ,if one exist. Image 3
Read more