Network

Type of Network

Personal Area Network (PAN)

1. A computer network used for communication among computer devices including PCs, laptops, and personal digital assistants, close to one person. 
2. May be wired with USB port, Firewire port, Infrared (IrDA) and Bluetooth technologies. Bluetooth is the popular wireless PAN used by most people.
3. IT applies the IEEE 802.15.1 standards.

Virtual Private Network (VPN)

1. A network that uses a public telecommunication infrastructure, such as the Internet, to remote offices or individuals with secure access to their organisation's private network. 
2. Uses tunnelling mechanism to maintain privacy and security of the data. Tunnelling means transmitting data packets across a public network. 
3. Often used by companies to provide access from their internal network resources to their home or mobile workers.

Wireless LAN (WLAN)

1. A type of LAN that uses high-frequency radio waves to communicate between nodes. 
2. Improves user mobility, speed and scalability to move around within a broad coverage area and still be connected to the network. 
3. The IEEE standard for Wireless LANs is 802.11.

Worldwide Interoperability for Microwave Access (WiMAX)

1. The industry term for broadband wireless access network that is developed based on the IEEE 802.16 standard.
2. A Wireless Metropolitan Area Network (MAN) technology that will connect WiFi hotspots to the Internet and provides a wireless extension to cable and DSL for larger broadband access. 
3. Operate similar to WiFi but at higher speeds, over greater distances and for a greater number of users.

A WiMAX system will have two major parts:

• WiMAX base station, similar in concept to a mobile phone tower
• WiMAX receiver installed at home

Communication

Network Communication Technology

• Intranet

           An Intranet is an internal network that uses Internet technologies and it is a
           small version of the Internet that exists within an organisation. It is a private
           computer network that uses Internet protocols, network connectivity and
           possibly the public telecommunication system to securely share part of an
           organisation’s information or operation with its employees.

• Extranet

           An extranet is a private network that uses Internet protocols, network
           connectivity, and possibly the public telecommunication system to securely
           share part of a business’s information or operations with suppliers, vendors,
           partners, customers or other businesses.

• Internet

           The Internet is the worldwide, publicly accessible system of interconnected 

           computer networks that transmit data by packet switching using the standard 

           Internet Protocol (IP). It consists of millions of smaller business, academic, 

           domestic and government networks, which together carry various information 

           and services, such as electronic mail, online chat, and the interlinked Web 

           pages and other documents of the World Wide Web.

Communication Device

Network Interface Card (NIC)

Function : 

• A network card adapter card or PC card that enables the computer to access the network.

Wireless Network Interface Card (WNIC)

Function : 

• A network card that  provides wireless data transmission.

Internal Modem

External Modem

Function :

•  A modem is a device that enables a computer to transmit data over telephone or cable lines.
• Coverts Analog signal to digital signal, vice versa.

    

Hub

Function : 

• Hubs/Switch are commonly used to connect segments of a LAN.
• A router is a communications device that connects multiple computers or other routers together and transmits data the correct destination.

Wireless Access Point

Function : 

• A wireless access point is a central communications device that allow computers to transfer data.
• This device can help information to be transferred wirelessly to other wireless devices or to a weird network.

Communication Technology

Telephone/Mobile Phone

Since the telephone's invention by Alexander Graham Bell in March of 1876, the telephone has come a long way. Telephones used landlines to send signals across the country, and later made use of undersea cables to let people communicate with those in other countries. The first cell phone, as the term is commonly understood, was invented in 1973, the first call being made by Dr. Martin Cooper of Motorola to his rival at Bell Labs. Since then, phones have come to enable much more than vocal communication, using tower and satellite signals to send text messages and data such as video and images.

Radio

Early radio communication was used primarily by the sea vessels in the 1900s and 1910s, with naval and merchant vessels making use of the technology for communicating with other ships. Radio on land started with advertising, but producers knew that people wouldn't listen unless they were entertained. Drama programs soon became a staple of popular radio in the late 1920s and early 1930s. Radio has since expanded to be a dominant form of communication technology; in September 2011, the FCC reported that there were 14,865 radio stations in the U.S. alone.

Television

Full-scale television broadcasting in the US began in 1947, and at first, many thought it would not last. Inventor Lee DeForest said, "While theoretically and technically television may be feasible, commercially and financially it is an impossibility." However, in the year 2010, U.S. households had over 115 million TVs, with almost 99 percent of households reporting owning at least one set. There are now thousands of TV channels covering everything from sports and music to reality shows, game shows and even adult entertainment.

Transmission Media

Transmission media is a pathway that carries the information from sender to receiver. We use different types of cables or waves to transmit data. Data is transmitted normally through electrical or electromagnetic signals.

Wired transmission media

Bound transmission media are the cables that are tangible or have physical existence and are limited by the physical geography.

Unshielded Twisted Pair Cable

The twisted-pair cable is generally a common form of transmission medium. It consists of two wires or conductors twisted together, each with its own plastic insulation. The twisted wires cancel out electromagnetic interference that can cause, the noise generated by adjacent pairs. Undesired coupling of a signal from one circuit, part of a circuit, or channel, to another. The most common connector used for twisted-pair cable is RJ-45.

• Shielded Twisted Pair Cable

The Shielded Twisted-Pair or STP is another form of twisted-pair cable. Twisted-pair cable wires that consist of anouter covering or shield. Its four pairs of colour-coded wires are each wrapped in metallic foil, and all four are then collectively wrapped in a layer of metallic braid or foil. Finally, this layer is wrapped with a plastic outer jacket.

• Coaxial Cable

The coaxial cable, often referred to as ‘coax’, consists of a single copper wire surrounded by at least three layers. They are an insulating material, a woven or braided metal and a plastic outer coating. This cable is often used as cable television (CATV) network wiring because it can be cabled over longer distances in comparison to the twisted-pair cable. This type of cable makes used of the BNC (Bayonet Neill–Concelman)connectors.

• Fibre Optic Cable

The fibre optic cable is a networking medium that uses light for data transmission. The intensity of light is increased and decreased to represent binary one and zero. The binary system is a way of counting using just the two numbers 0 and 1. Its core consists of dozens or hundreds of thin strands of glass or plastic which uses light to transmit signals. Each strand, called an optical fibre, is as thin as a human hair.

Wireless transmission media

Unbound transmission media are the ways of transmitting data without using any cables. These media are not bounded by physical geography.

• Satellite

This is a space station that receive microwave signals from an earth-based station, amplifies the signals, and broadcasts the signal back over a wide area to any number of earth-based station. A transmission from the earth to a satellite is called an uplink; a transmission from a satellite to an earth station is called a downlink. Communication satellites are used in application such as air navigation, television and radio broadcast , videoconferencing and paging.

• Microwave

These are radio waves that provides a high-speed signal transmission; from one microwave station to another; which are normally located on the top of buildings, towers or mountain . Microwave signals must be transmitted in as straight line with o obstructions between microwave antennas.

• Infrared 

Is a wireless transmission media that sends signals using infrared light waves. Infrared transmission requires a line of sight transmission, that is the sender and receiver must be aligned so that nothing obstructs the path of infrared light wave.

• Bluetooth

This is an open wireles protocol for exchanging data over short distances (using short radio waves) from fixed and mobile devices. It can connect several devices, overcoming problems of synchronization.

Communication Protocol

A communication protocol is a system of rules that allow two or more entities of a communications system to transmit information via any kind of variation of a physical quantity. These are the rules or standard that defines the syntax, semantics and synchronization of communication and possible error recovery methods. Protocols may be implemented by hardware, software, or a combination of both.

Type of Communication Protocol

• TCP/IP

           The Internet protocol suite is the computer networking model and set of 

           communications protocols used on the Internet and similar computer networks.
           It is commonly known as TCP/IP, because its most important protocols, the
           Transmission Control Protocol (TCP) and the Internet Protocol (IP) were the
           first networking protocols defined during its development.

• SMTP

           Simple Mail Transfer Protocol (SMTP) is an Internet standard for electronic
           mail (email) transmission. First defined by RFC 821in 1982, it was last updated
           in 2008 with the Extended SMTP additions by RFC 532 which is the protocol
           in widespread use today.

• AppleTalk

          AppleTalk was a proprietary suite of networking protocols developed by Apple
          Inc. for their Macintosh computers. AppleTalk includes a number of features
          that allow local area networks to be connected with no prior setup or the need
          for a centralized router or server of any sort. Connected AppleTalk-equipped
          systems automatically assign addresses, update the distributed namespace, and
          configure any required inter-networking routing. It is a plug-n-play system.

Network Topology

Network topology is the arrangement of the various elements (links, nodes, etc.) of a computer network. Essentially, it is the topological structure of a network and may be depicted physically or logically.

Types of Network Topology

Bus Topology

• There is a single central cable (backbone) and all computers and other devices connect to it
• A lot number of nodes when extending network
• Easy to add and remove nodes
• Difficult to troubleshooting
• Network still can run if node fail
• Network still can if host fail
• No connection between nodes
• Host existence depends on network needs

Ring topology

• All computers and other devices are connected in a circle
• Limited number of nodes when extending network
• Difficult to add and remove nodes
• Depends on backbone. If there is a backbone problem, troubleshooting is difficult. If there is no backbone problem, the focus is on the two nodes not communicating
• Network will fail if node fail
• Network will fail if host fail
• Have connection between nodes
• Host existence depends on network needs

Star topology

• There is a central host and all nodes connect to it
• Limited number of nodes when extending network
• Average to add and remove nodes
• There is a central host and all nodes connect to it
• Network still can run if node fail
• Network will fail if host fail
• No connection between nodes
• Have host existance

Network Architecture

Network architecture is the design of a communication network. It is a framework for the specification of a network's physical components and their functional organization and configuration, its operational principles and procedures, as well as data formats used in its operation.

Types of Network Architecture

• Client/Server

           A client/server network is a network in which the shared files and applications
           are stored in the server but network users (clients) can still store files on their
           individual PCs

• Peer-to-Peer

           Peer-to-Peer network is a network with all the nodes acting as both severs and
           clients. Can access files located on another PC and can also provide files to
           other PCs. No server is needed, each computer in the network is called a peer. 
           Has equal responsibilities and capabilities use the resources available on the 
           network.

Computer Networks

Type of Computer Networks

• Local Area Network (LAN)

• Metropolitan Area Network (MAN)

• Wide Area Network (WAN)

A LAN covers a small region of space, typically a single building such as school lab.

• Small size of network
• Very high speed of network
• Transmission media; Twisted pair
• Smallest number of computer

A MAN is a collection of LANs with the same geographical area, for instance a city such as Kuala Lumpur

• Larger size of network
• High speed of network
• Transmission media; Twisted pair and Fibre Optic Cable
• Large number of computer

A WAN can be a collection of LANs or MANs or the mix of two with a very large geographical area, for instance a country or even beyond the border such as between Kuala Lumpur and London

• Largest size of network 
• Slow speed of network 
• Transmission media; Fibre Optic, Radio wave and Sattelite 
• Largest number of computer

Computer Network and Communication

Definition

• Computer Network

           Computer network is a system of interconnected computers and peripheral 

           devices. For example, it may connect computers, printers, scanners and 

           cameras

• Communication

           Communication is about the transfer of information from a sender, across a 

           distance, to a receiver. Using electricity, radio waves or light, information and 

           data in the form of codes are transmitted through a physical medium such as 

           wire, cable or even the atmosphere