Computer Network
Chapter Focuses on :
● What is Networking?
● Types of Network
● Disadvantages of Networking
● Network Architecture
● Network Components
● Advantages of Networking
● Network Topologies
WHAT IS NETWORKING?
A computer network is a set of computers connected together for the purpose of sharing resources. The most common resource shared today is connection to the Internet. Other shared resources can include a printer or a file server.
The Internet itself can be considered as a computer network. Computers on a network are called nodes. Communication links can be a copper wire, fibre optics, microwaves, infrared and communication satellites. These links allow the network components to work together. Computer networks can be of any size. A computer network can be created connecting two computers or millions of computers. When your computer is a part of a network using a cable or some other communication channels, you can become a network user, now you can share files, folders and
Network Ring computer hardware such as printers attached with one computer to other computers. These usual resources
Do You Know? referred to as local resources. Network can be classified
Wireless networking allows into LAN, MAN and WAN.
networks to be deployed without cabling. Spaces such as outdoor
NETWORK COMPONENTS
areas where cables cannot be put; To establish wired networking in a group of computers,can have wireless network. we require the following additional components :
a. Network Card A network card is used to physically attach a computer to a network, so that it can participate in network communication. Ethernet Network Card is the most commonly used network card.
b. Cables Cables are required to connect computers and resources on a network Various kinds of cables can be used depending on the type and size of the network. They are the information transfer medium on a computer network.
c. Hubs and Switches Network cards are used to send and receive data being transmitted over Ethernet cables. When a network has more than two computers, we cannot directly connect all the computers together. We need an interface through which the computers can be connected, and sending and receiving of data can take place. This function is performed by a hub or a switch. Hubs were the preferred medium in earlier times but now switches are being used because of their better efficiency.
d. Access Points or Routers These have a wireless antenna which increases the communication range of the radio signals. Access point can also be used to join a wired network. Thus, making the network a combination of wired as well as wireless network.
TYPES OF NETWORK
Networks are of different types and sizes. Distance is important as a classification metric because different techniques are used at different scales. Different types of networks are as follows:
1. LAN (Local Area Network) LAN refers to a network that connects computers spread over a limited geographical area such as a school, a building, adjacent buildings, etc. In LAN, two or more computers and peripheral devices are connected within a small area. In this network, computer terminals are physically connected with wires.
2. MAN (Metropolitan Area Network) A Metropolitan Area Network covers a city or a town. The best known example of MAN is the cable television network available in many cities. Metropolitan Area Network is wider than that of a Local Area Network.
3. WAN (Wide Area Network) This kind of network connects two or more computers located at far away places. They are linked by communication facilities like telecommunication or satellite signals. The most common example of WAN type network is telecom system. The usage of WAN is limited to a very large organizations and government agencies. The main characteristics of WAN is that it requires a public telecommunication media to transfer data. The best examples of WAN are:
· Internet and Intranet in a large multinational company.
· ATM facility is the result of WAN.
· Multinational bank customer services.
ADVANTAGES OF NETWORKING
Networking of computers has many advantages.
They are :
a. Communication A computer can provide a powerful communication medium among people. For example, in a large company, the employees and computers may be scattered in many countries. They have to communicate and send daily report to each other using e-mail facility.
b. Allows File Sharing Computer networking allows accessibility for the people to share their files easily. This greatly helps the people in saving their time and effort since they could already share some of the important files they need to share with other people effectively and accordingly. posted
c. Resource Sharing This benefit is very important, particularly for larger companies that really need to produce huge numbers of resources to be shared to all the people. Since the technology involves computer-based work, it is assured that the resources they wanted to get across would be completely shared by connecting to a computer network which their audience is also using.
d. Flexible to be used Computer networking is known to be very flexible since you are given the chance to explore everything about the software without affecting its functionality. You will have accessibility to all the information that needs to be shared.
e. It Increases Cost Efficiency With computer networking, you can use a lot of software products available on the market which can just be stored or installed in your system or server, and can then be used by various workstations.
DISADVANTAGES OF NETWORKING
a. Presence of Computer Viruses and Other Malware There are instances that the stored file you have in your gadget is already destroyed because there are already viruses that corrupt your file. Hence you need to have regular check-up on your gadget at the same time to the stored files you have.
b. Lack of Independence Since computer networking is a process operated through computers, people are already relying more of the works of the computer rather than exerting an effort for their works.
c. It lacks Robustness If a computer network's main server breaks down, the entire system would become useless. Also, if it has a bridging device or a central linking server that fails, the entire network would also come to a standstill. To deal with these problems, huge networks should have a powerful computer to serve as file server to make setting up and maintaining the network easier.
d. It Requires an Efficient Handler For a computer network to work efficiently and optimally, it requires high technical skills and know-how of its operations and administration. A person just having basic skills cannot do this job. Take note that the responsibility to handle such a system is high, as allotting permissions and passwords can be daunting. Similarly, network configuration and connection is very tedious and cannot be done by an average technician who does not have advanced knowledge.
NETWORK TOPOLOGIES
The term topology refers to the way in which computers are physically attached together on the network. Below are given some important network topologies.
1. Bus Topology Bus topology
Bus Topology Bus topology uses one main cable to which all nodes are directly connected. The main cable acts as a backbone for the network. One of the computers in the network typically acts as the computer server. It is the simplest of network topologies. Every workstation communicates with the other device through this bus.
Advantages of Bus Topology
a. It is easy to set-up and extend bus network.
b. Bus topology costs very less.
c. This topology is mostly used in small networks. It is good for LAN.
d. Cable length required for this topology is the least compared to other networks.
Disadvantages of Bus Topology
a. The cable length and number of nodes that can be connected are limited.
b. It is difficult to detect and troubleshoot fault at individual station.
c. It is not suitable for networks with heavy traffic.
d. Security is very low because all the computers receive the sent signal from the source.
2. Ring Topology In ring topology,
the computer in the network are connected in a circular fashion. Each computer is directly connected to the next computer, forming a single pathway for signals through the network. This type of network is easy to install and manage. Data travels around the network in one direction. Advantages of Ring Topology
a. This type of network topology is very organised. Each node gets to send the data when it receives an empty token. This helps to reduce chances of collision.
b. Even when the load on the network increases, its performance is better than that of bus topology
c. There is no need for network server to control the connectivity between workstations.
d. Additional components do not affect the performance of network.
Disadvantages of Ring Topology
a. If one workstation goes down, the entire network gets affected.
b. Network is highly dependent on the wire which connects different components.
c. Because all stations are wired together, to add a station you must shut down the network
temporarily. In order for all computers to communicate with each other, all computers must be turned on.
3. Star Topology In star topology,
each computer is connected to a central hub using a point-to-point connection. The central hub can be a computer server that manages the network, or it can be a much simpler device that only makes the connections between computers over the network possible. All the data on the star topology passes through the central device before reaching the intended destination.
Advantages of Star Topology
1. As compared to bus topology, it gives far much better performance, signals don't necessarily get transmitted to all the workstations. A sent signal reaches the intended destination after passing through not more than 3-4 devices and links.
2. It is easy to connect new nodes and devices in this topology.
3. It has a centralized management which helps in monitoring the network
4. Failure of one node or link doesn't affect the rest of the network. At the same time, its easy to detect the failure and troubleshoot it.
Disadvantages of Star Topology
1. It is very expensive to install.
2. Extra hardware is needed in this topology.
3. If the connecting network device fails, nodes attached are disabled and cannot participate in network communication.
4.Tree Topology
A tree topology joins multiple star topologies together into a bus. In its simplest form, only hub devices connect directly to the tree bus, and each hub functions as the root of a tree of devices. In this topology, the number of star networks are connected using bus. Thus main cable seems like a main stem of a tree and other star networks as the branches. It is also called Expanded Star Topology.
Advantages of Tree Topology
1. Expansion of network is possible and easy.
2. Error detection and correction is easy.
3. If one segment is damaged, other segments are not affected.
4. A tree network provides enough room for future expansion. Disadvantages of Tree Topology
1. With increase in size beyond a point, the management becomes difficult.
2. Scalability of the network depends on the type of cable used.
3. Because of its basic structure, tree topology relies heavily on the main bus cable, if it breaks whole network is crippled.
5. Hybrid Topology
Hybrid, as the name suggests, is a mixture of two different things. Similarly in this type of topology, we $
3 0 0 integrate two or more different topologies to form a resultant topology which has good points (as well as u weaknesses) of all the constituent basic topologies rather than having characteristics of one specific topology. This combination of topologies is done according to the requirements of the organization. Se
Hybrid Topology
Advantages of Hybrid Topology
a. Unlike other networks, fault detection and troubleshooting is easy in this type of topology. The part in which fault is detected can be isolated from the rest of network and required corrective measures can be taken without affecting the functioning of the rest of the network.
b. These networks are constructed in a modular fashion that allows for easy integration of new hardware components like additional concentration points.
c. Hybrid network can be designed according to the requirements of the organization and by optimizing the available resources.
Disadvantages of Hybrid Topology
a. The network hubs required for hybrid technology networking are expensive to purchase and maintain.
b. As hybrid architectures are usually larger in scale, they require a lot cables, cooling systems, sophisticated network devices, etc.
6. Mesh Topology
Mesh topology introduces the concept of routes. Unlike each of the previous topologies, messages sent on a mesh network can take any of several possible paths from source to destination. Some WANs, most notably the Internet employ mesh routing.
Advantages of Mesh Topology
a. In this topology, data is transmitted from different devices cumulatively.
b. It removes or eliminates the traffic problems in the form of link sharing
Disadvantages of Mesh Topology
a. This topology is difficult to install and control or maintain.
b. It is expensive.
c. High opportunity of redundancy.
NETWORK ARCHITECTURE
Network architecture is an overall design of a computer network that describes how a computer network configured and what strategies are being used. Computer networks are of two main types:
1. Client-Server Network A client-server network is designed for end-users, called clients, to access resources such as files, songs, video collections, or some other service from a central computer called a server. A server is a computer that provides services to clients and controls access to hardware, software and other resources. Clients are the computer which request services like data retrieval, storage, etc. from the server.
2. Peer-To-Peer Network Peer-to-Peer is a network where a few computer having equal capacity and capabilities are connected together to use the resources available on the network. In peer-to-peer network, there is no central server. Each computer can act as a server as well as client.
Let's RECAPITULATE
· A computer network is a set of computers connected together for the purpose of sharing resources.
· Network card, cables, hubs and switches, routers are important network components.
· LAN, MAN and WAN are the three types of networks.
· The term topology refers to the way in which computers are physically attached together on the network. * Bus, Ring, Star, Tree, Hybrid and Mesh are the different types of topologies. + Computer architecture consists of two types of network; Client-Server network and Peer-to-peer network.
Assessment TIME (do your self)
A. Tick () the correct option.
1) Two or more computers are connected together in a .......
a. school
b. network
c. building
d. home
2) A network ideal for networking in a large geographical area is .
a. MAN
b. LAN T
c. WAN
d. CAN
3) Which topology uses one main cable to which all nodes are directly connected?
a. Star
b. Ring
c. Bus
d. Mesh
4) In a topology, data travels around the network in one direction.
a. tree
b. ring
c. hybride
d. bus
5) Which topology is a combination of two topologies?
a. Hybrid
b. Mesh
c. Bust
d. Ring
B. Fill in the blanks.
1. Computers on a network are called .....nada......
2...... ... ........ are the information transfer medium on a computer network.
3. Cheshpult network card is the most commonly used network card.
4. A...H A.......... area network covers a city or a town.
5. All the data on the .....65.....Ha....... topology passes through the central device before reaching
the intended destination.
C. State whether the following statements are True or False.
1. A computer network can be created by connecting two computers or millions of computers.
2. In a network, distance is not important as a classification metric.
3. A computer can provide a powerful communication medium among people.
4. ATM facility is the result of WAN.
5. A tree topologies join multiple ring topologies in a bus.
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