Computer Network Assignment A134591 & A135410

CONTENT
TYPICAL STRUCTURE OF THE ASSIGNMENT VIA WIKI IS:

I. INTRODCUTION

II. BACKGROUND

III. BENIFITS

IV. WHAT IS NETWORK CLASSIFICTION

V. TWO TYPS OF NETWORKS BASED ON PHYSICAL SCOPE

VI. BASIC HARDWARE COMPONENTS

VII. CONCLUSION

VIII. REFERENCES

INTRODUCTION
A computer network, often simply referred to as a network, is a group of computer and devices interconnected by communications channels that facilitate communications among users and allows users to share resources.Computer networks is an international, archival journal providing a publication vehicle for complete coverage of all topics of interest to those involved in the computer communications networking area.The connection can be done as peer-to-peer or client/server or simply by two connected computers.A computer network also referred to as client/server if (at least) one of the computers is used to "serve" other computers referred to as "clients". Besides the computers, other types of devices can be part of the network.

BACKGROUND
The field of computer networking and today's Internet trace their beginnings back to the early 1960s, a time at which the telephone network was the world's dominant communication network. The global Internet's origin was the Advanced Research Projects Agency Network (ARPANET) of the U.S. Department of Defense in 1969. Here are some of the highlights of the progression of computer networking within the last 35 years.

1974 - Ethernet is demonstrated by networking Xerox PARC’s new Alto computers.

1978 - The appearance of the first very small computers and their potential for communication via modem to dial up services.

1981 - Bill Joy incorporates the new TCP/IP suite into the next release of the UNIX operating system. The first “portable” computer is launched in the form of the Osborne, a 24 pound suitcase sized device.

1981 - The IBM PC is launched

1982 - TCP/IP (Transmission Control Protocol and Internet Protocol) is established as the standard for ARPANET.

1983 - ARPANET standardizes on the TCP/IP protocols adopted by the Department of Defense.

1986 - TCP/IP is available on workstations and PCs such as the newly introduced Compaq portable computer.

1987 - The number of network hosts breaks 10,000.

1989 - The number of hosts breaks 100,000.

1990 - ARPANET formally shuts down. Several search tools, such as ARCHIE, Gopher, and WAIS start to appear.

1991 - The NSFNET backbone upgrades to T3 (44 Mbps). A wide-area network developed under the auspices of the National Science Foundation. NSFnet replaced ARPANET as the main government network linking universities and research facilities.

1991- Tim Berners-Lee develops the World Wide Web. Lee is the director of the World Wide Web Consortium, which oversees its continued development. CERN also releases the first Web server.

1992 - The WWW bursts into the world and the growth of the Internet explodes.

BENIFITS

 * file sharing - Network file sharing between computers gives you more flexibity than using floppy drives or Zip drives. Not only can you share photos, music files, and documents, you can also use a home network to save copies of all of your important data on a different computer. Backups are one of the most critical yet overlooked tasks in home networking.


 * printer / peripheral sharing - Once a home network is in place, it's easy to then set up all of the computers to share a single printer. No longer will you need to bounce from one system or another just to print out an email message. Other computer peripherals can be shared similarly such as network scanners, Web cams, and CD burners.


 * Internet connection sharing - Using a home network, multiple family members can access the Internet simultaneously without having to pay an ISP for multiple accounts. You will notice the Internet connection slows down when several people share it, but broadband Internet can handle the extra load with little trouble. Sharing dial-up Internet connections works, too. Painfully slow sometimes, you will still appreciate having shared dial-up on those occasions you really need it.


 * multi-player games - Many popular home computer games support LAN mode where friends and family can play together, if they have their computers networked.


 * Internet telephone service - So-called Voice over IP (VoIP) services allow you to make and receive phone calls through your home network across the Internet, saving you money.

Although you can realize these same benefits with a wired home network, you should carefully consider building a wireless home network instead, for the following reasons:
 * home entertainment - Newer home entertainment products such as digital video recorders (DVRs) and video game consoles now support either wired or wireless home networking. Having these products integrated into your network enables online Internet gaming, video sharing and other advanced features.

1. Computer mobility. Notebook computers and other portable devices are much affordable than they were a few years ago. With a mobile computer and wireless home network, you aren't chained to a network cord and can work on the couch, on your porch, or wherever in the house is most convenient at the moment.

2. No unsightly wires. Businesses can afford to lay cable under their floors or inside walls. But most of us don't have the time or inclination to fuss with this in our home. Unless you own one of the few newer homes pre-wired with network cable, you'll save substantial time and energy avoiding the cabling mess and going wireless.

3. Wireless is the future. Wireless technology is clearly the future of networking. In building a wireless home network, you'll learn about the technology and be able to teach your friends and relatives. You'll also be better prepared for future advances in network technology coming in the future.

Technically speaking networking can be defined as a bunch of computers that have with wires running in between them. If proper implementation of a network is done it acts as a system that provides unique capabilities, to its users. These are much beyond the abilities of individual machines and software applications associated with them. The benefits networking offers to its users can be separated into two main groups i.e. sharing and connectivity. Networks make computers and their users capable of being connected together. This facilitates sharing of resources and information between the users. The modern businesses are expanded all over the world. So, uses and significance of networking has gained momentum during the last years. The many benefits that networking offers to us are:

1.Helps to enhance connectivity .Networks connect and link unlimited number of computers'''. ''' This in turn connects the people using those computers. Individuals within a work group are connected through local area networks. Many LANs in far off locations are interconnected through larger wide area networks (WANs). These connections ease out communication between people using technologies like e-mail. Today e-mail has become the easiest, and cheapest mode of transformation of information between the users.

2.Networking helps in sharing of hardware: Networks help in sharing of different kinds of hardware devices. For example, sharing of a single printer in an office of twenty people is done through networking of wires. This saves lot of cost that could otherwise have incurred if twenty different printers were provided for each computer in use.

3.Eases out management of data. Networking provides the advantage of centralization of data from all the user systems to one system where it can be managed in an easy and better way. Administrators can thus manage all this data efficiently and in the best interest of the company. Even the access of this data becomes easy for the users.

4.Internet. The most beautiful gift of networking is internet that is massively used by people all over the world. Whenever you are accessing Internet, you are making use of a network. The benefits of internet need no mentioning. Thanks to the wonderful world of networking.

5.Data Sharing. Sharing of data through the use of networks helps save a lot of time and energy. It also facilitates the use of applications like databases that are based on ability of many individuals to access and to share exactly the same data.

6.Networking has promoted gaming Many internet games like WOW accounts are being played by players all over the world using common servers. These give fun and enjoyment to people and also improve their skills.Such are the varied benefits of networking to the people all over the world. The success of networking in providing benefits to people depends upon the frequency of its use. So, make the maximum out of this wonderful gift of technology to a man.

WHAT IS NETWORK CLASSIFICTION
1. Network Topology

Computer networks may be classified according to the Network Topology upon which the network is based, such as Bus Network, Star Network, Mesh Network, Bus-Star Network, Tree or Hierarchical topology network and etc. Network Topology signifies the way in which intelligent devices in the network see their logical relations to one another. The use of the word "logical" is significant. Thus the network Topology independent the "physical" layout of the network. Even if networked computers are physically placed in a linear arrangement, if they are connected via a hub, the network has a Star topology, rather than a Bus Topology. In this regard the visual and operational characteristics of a network are distinct; the logical network topology is not necessarily the same as the physical layout.

2. Connection method

Computer networks can be classified according to the hardware and software technology that is used to interconnect the individual devices in the network, such as ,optical fibre,Ethernet,wireless LAN,HomePNA,power line communication or G.hn. Ethernet uses physical wiring to connect devices. Frequently deployed devices include hubs, switches, bridges, or routers. Wireless LAN technology is designed to connect devices without wiring. These devices use radio waves or infrared signals as a transmission medium.ITU-G.hn technology uses existing homewriting(coaxial cable phone lines and power line) to create a high-speed (up to 1 Gigabit/s) local area network.

Wired technologies

a. Twisted pair wire is the most widely used medium for telecommunication. Twisted-pair wires are ordinary telephone wires which consist of two insulated copper wires twisted into pairs and are used for both voice and data transmission. The use of two wires twisted together helps to reduce crosstalk and electromagnet induction. The transmission speed ranges from 2 million bits per second to 100 million bits per second.

b. Coaxial cable is widely used for cable television systems, office buildings, and other worksites for local area networks. The cables consist of copper or aluminum wire wrapped with insulating layer typically of a flexible material with a high dielectric constant, all of which are surrounded by a conductive layer. The layers of insulation help minimize interference and distortion. Transmission speed range from 200 million to more than 500 million bits per second.

c. Optic fibre cable consists of one or more filaments of glass fiber wrapped in protective layers. It transmits light which can travel over extended distances. Fiber-optic cables are not affected by electromagnetic radiation. Transmission speed may reach trillions of bits per second. The transmission speed of fiber optics is hundreds of times faster than for coaxial cables and thousands of times faster than a twisted-pair wire

Wireless technologies

a. Terrestrial microwave – Terrestrial microwaves use Earth-based transmitter and receiver. The equipment look similar to satellite dishes. Terrestrial microwaves use low-gigahertz range, which limits all communications to line-of-sight. Path between relay stations spaced approx, 30 miles apart. Microwave antennas are usually placed on top of buildings, towers, hills, and mountain peaks.

b. Communications satellite – The satellites use microwave radio as their telecommunications medium which are not deflected by the Earth's atmosphere. The satellites are stationed in space, typically 22,000 miles (for geosynchronous satellites) above the equator. These Earth-orbiting systems are capable of receiving and relaying voice, data, and TV signals.

c. Cellular and PCS systems – Use several radio communications technologies. The systems are divided to different geographic areas. Each area has a low-power transmitter or radio relay antenna device to relay calls from one area to the next area. d. Wireless LANs – Wireless local area network use a high-frequency radio technology similar to digital cellular and a low-frequency radio technology. Wireless LANs use spread spectrum technology to enable communication between multiple devices in a limited area. An example of open-standards wireless radio-wave technology is IEEE. e. Infrared Communication - which can transmit signals between devices within small distances not more than 10 meters peer to peer or ( face to face ) without any body in the line of transmitting.

Scale

Networks are often classified as local area network(LAN),wide area network (WAN), metropolitan area network (MAN), personal area network (PAN), virtual privatge network (VPN), campusarea network (CAN), storagearea network (SAN), and others, depending on their scale, scope and purpose, e.g., controlled area network (CAN) usage, trust level, and access right often differ between these types of networks. LANs tend to be designed for internal use by an organization's internal systems and employees in individual physical locations, such as a building, while WANs may connect physically separate parts of an organization and may include connections to third parties.

Functional relationship (network architecture)

Computer networks may be classified according to the functional relationships which exist among the elements of the network, e.g.,active network and peer-to-peer (workgroup) architecture.

Individual networked devices are assigned to appropriate VLANs based on the type of users which have access to them. The possible network classifications are:

The user categories map to the network categories as follows:
 * Undergraduate Network
 * Postgraduate Coursework Network
 * Postgraduate Research Network
 * Staff Network
 * Wireless Network
 * Unregistered Network
 * Restricted Network
 * External Network

The other network types are for special purposes (regardless of the type of users).
 * Undergraduate Student, Student Visitors and Guests Undergraduate Network
 * Honours Student, Postgraduate Coursework Student Postgraduate Coursework Network
 * Postgraduate Research Student, Staff Visitors and Guests Postgraduate Research Network
 * Staff Members Staff Network

Comments on implementation
The user and network classifications above are based on the level of trust that the Department places in each type of user. It is intended that this policy is one step abstracted from the actual implementation. For example, there can be separate VLANs for Technical, Admin and Academic staff members, but all will have the same access privileges as they will all be classified as Staff Networks.

The following lists of allowed and denied traffic will need to be modified once this policy is implemented based on actual results. These lists are a best approximation in the absence of empirical evidence.

TWO TYPES OF NETWORKS BASED ON PHYSICAL SCOPE
1. LOCAL AREA NETWORK(LAN) - A local area network (LAN) is a network that connects computers and devices in a limited geographical area such as home, school, computer laboratory, office building, or closely positioned group of buildings. Each computer or device on the network is a node. Current wired LANs are most likely to be based on Ethernet technology, although new standards like ITU-T G.hn also provide a way to create a wired LAN using existing home wires (coaxial cables, phone lines and power lines).

Privately-owned networks covering a small geographic area, like a home, office, building or group of buildings (e.g. campus). They are widely used to connect computers in company offices and factories to share resources (e.g., printers) and exchange information. LANs are restricted in size, which means that the worst-case transmission time is bounded and known in advance. Knowing this bound makes it possible to use certain kinds of designs that would not otherwise be possible. It also simplifies network management. Traditional LANs run at speeds of 10 Mbps to 100 Mbps, have low delay (microseconds or nanoseconds), and make very few errors. Newer LANs operate at up to 10 Gbps. The interprocessor distance is 10 meters to 1 kilometer and the processors are located in a room or a building or a campus.

All interconnected devices must understand the network layer (layer 3), because they are handling multiple subnets (the different colors). Those inside the library, which have only 10/100 Mbit/s Ethernet connections to the user device and a Gigabit Ethernet connection to the central router, could be called "layer 3 switches" because they only have Ethernet interfaces and must understand IP. It would be more correct to call them access routers, where the router at the top is a distribution router that connects to the Internet and academic networks' customer access routers.

The defining characteristics of LANs, in contrast to WANs (Wide Area Networks), include their higher data transfer rates, smaller geographic range, and no need for leased telecommunication lines. Current Ethernet or other IEEE 802.3 LAN technologies operate at speeds up to 10 Gbit/s. This is the data transfer rate. IEEE has projects investigating the standardization of 40 and 100 Gbit/s.

2.WIDE AREA NETWORKS(WAN) -

A wide area network (WAN) is a computer network that covers a large geographic area such as a city, country, or spans even intercontinental distances, using a communications channel that combines many types of media such as telephone lines, cables, and air waves. A WAN often uses transmission facilities provided by common carriers, such as telephone companies. WAN technologies generally function at the lower three layers of the OSI reference model: the physical layer, the data link layer, and the network layer.

Computer network that covers a large geographical area, often a country or continent. (any network whose communications links cross metropolitan,regional, or national boundaries). Less formally, a network that uses routers and public communications links. The interprocessor distance is from 100 kilometers to 1000 kilometers and the processors are located in a country or a continent.

BASIC HARDWARE COMPONENTS
Computers come in all types and sizes. There are primarily two main sizes of computers. They are: The portable computer comes in various sizes and are referred to as laptops, notebooks, and hand-held computers. These generally denote different sizes, the laptop being the largest, and the hand-held is the smallest size. This document will mainly talk about the desktop computer although portable computer issues are also discussed in various areas.
 * Portable
 * Desktop

Computer Components:
Computers are made of the following basic components:
 * 1) Case with hardware inside:
 * 2) Power Supply - The power supply comes with the case, but this component is mentioned separately since there are various types of power supplies. The one you should get depends on the requirements of your system. This will be discussed in more detail later


 * 1) Motherboard - This is where the core components of your computer reside which are listed below. Also the support cards for video, sound, networking and more are mounted into this board.
 * 2) Microprocessor - This is the brain of your computer. It performs commands and instructions and controls the operation of the computer.
 * 3) Memory - The RAM in your system is mounted on the motherboard. This is memory that must be powered on to retain its contents.
 * 4) Drive controllers - The drive controllers control the interface of your system to your hard drives. The controllers let your hard drives work by controlling their operation. On most systems, they are included on the motherboard, however you may add additional controllers for faster or other types of drives.
 * 5) Hard disk drive(s) - This is where your files are permanently stored on your computer. Also, normally, your operating system is installed here.


 * 1) CD-ROM drive(s) - This is normally a read only drive where files are permanently stored. There are now read/write CD-ROM drives that use special software to allow users to read from and write to these drives.


 * 1) Floppy drive(s) - A floppy is a small disk storage device that today typically has about 1.4 Megabytes of memory capacity.


 * 1) Other possible file storage devices include DVD devices, Tape backup devices, and some others.
 * 2) Monitor - This device which operates like a TV set lets the user see how the computer is responding to their commands.


 * 1) Keyboard - This is where the user enters text commands into the computer.

These various parts will be discussed in the following sections.
 * 1) Mouse - A point and click interface for entering commands which works well in graphical environments.

All networks are made up of basic hardware building blocks to interconnect network nodes, such as Network Interface Cards (NICs), Bridges, Hubs, Switches, and Routers. In addition, some method of connecting these building blocks is required, usually in the form of galvanic cable (most commonly Category 5 cable). Less common are microwave links (as in IEEE 802.12) or optical cable ("optical fiber").

Network interface cards
A network card, network adapter, or NIC (network interface card) is a piece of computer hardware designed to allow computers to communicate over a computer network. It provides physical access to a networking medium and often provides a low-level addressing system through the use of MAC addresses.

Repeaters
A repeater is an electronic device that receives a signal, cleans it of unnecessary noise, regenerates it, and retransmits it at a higher power level, or to the other side of an obstruction, so that the signal can cover longer distances without degradation. In most twisted pair Ethernet configurations, repeaters are required for cable that runs longer than 100 meters. Repeaters work on the Physical Layer of the OSI model.

Hubs
A network hub contains multiple ports. When a packet arrives at one port, it is copied unmodified to all ports of the hub for transmission. The destination address in the frame is not changed to a broadcast address.It works on the Physical Layer of the OSI model.

Bridges
A network bridge connects multiple network segments at the data link layer (layer 2) of the OSI model. Bridges broadcast to all ports except the port on which the broadcast was received. However, bridges do not promiscuously copy traffic to all ports, as hubs do, but learn which MAC addresses are reachable through specific ports. Once the bridge associates a port and an address, it will send traffic for that address to that port only.

Bridges learn the association of ports and addresses by examining the source address of frames that it sees on various ports. Once a frame arrives through a port, its source address is stored and the bridge assumes that MAC address is associated with that port. The first time that a previously unknown destination address is seen, the bridge will forward the frame to all ports other than the one on which the frame arrived.

Bridges come in three basic types:
 * Local bridges: Directly connect local area networks (LANs)
 * Remote bridges: Can be used to create a wide area network (WAN) link between LANs. Remote bridges, where the connecting link is slower than the end networks, largely have been replaced with routers.
 * Wireless bridges: Can be used to join LANs or connect remote stations to LANs.

Switches
A network switch is a device that forwards and filters OSI layer 2 datagrams (chunk of data communication) between ports (connected cables) based on the MAC addresses in the packets.[8] A switch is distinct from a hub in that it only forwards the frames to the ports involved in the communication rather than all ports connected. A switch breaks the collision domain but represents itself as a broadcast domain.

Switches make forwarding decisions of frames on the basis of MAC addresses. A switch normally has numerous ports, facilitating a star topology for devices, and cascading additional switches.[9] Some switches are capable of routing based on Layer 3 addressing or additional logical levels; these are called multi-layer switches. The term switch is used loosely in marketing to encompass devices including routers and bridges, as well as devices that may distribute traffic on load or by application content (e.g., a Web URL identifier).

Conclusion
The York/Habitat Networking Initiative showed that in the absence of resources allocated to promote collaborative activities among people busy with their own current endeavours, it is very difficult to maintain interpersonal interactions. A great deal of organizing must be done by those most involved in establishing a new network, especially one that links people across several traditional fields.

The Native Computer Communications Network Project was a good example of how a focus on creating a network of computers does not necessarily ensure the interpersonal networking of the potential users of that technology. If the people were not communicating with each other before, developing another method of communication doesn't mean they'll start.

Habnet was a project that tried to overcome the limitations of these initiatives. It succeeded as an exploration of the potentials of online interactions, but failed to thrive when it ceased to grow. It again showed how difficult it is to create an online network without sufficient numbers of people to maintain enough interaction, and thereby enough interest, to make it worthwhile to use.

Computer communication, it seems, will become a much more useful networking tool when large numbers of people with similar interests acquire access to the technology. Though it can expedite the formation of new interpersonal networks by overcoming the space and time barriers faced by traditional networking techniques, it still requires a great deal of concentrated effort and resources to get the people to use it. This problem should become increasingly minimized over the coming years as the technological innovations become more diffused throughout society.

While the age-old concept of the network is foundational in virtually all areas of society, Computer Networks and Protocols have forever changed the way humans will work, play, and communicate. Forging powerfully into areas of our lives that no one had expected, digital networking is further empowering us for the future. New protocols and standards will emerge, new applications will be conceived, and our lives will be further changed and enhanced. While the new will only be better, the majority of digital networking's current technologies are not cutting-edge, but rather are protocols and standards conceived at the dawn of the digital networking age that have stood solid for over thirty years.