Embedded Files
Lesson Objectives:
Define computer networks and describe their purpose
a. Define a computer network.
b. List the four purposes of a network.
c. Explain the elements of communication in a computer network.
d. List and describe the two types of networks.
What is Computer Network?
Ang computer network ay ang pagkakaugnay-ugnay ng mga computing devices (gaya ng laptops, desktops, servers, smartphones, at tablets) at ng mga lumalaki pang Internet of things(IoT) devices (gaya ng cameras, door locks, doorbells, refrigirators, audio/visual systems, thermostats, at iba-ibang sensors) na nagkakapag usap sa bawat isa.
Computer networking refers to connected computing devices (such as laptops, desktops, servers, smartphones, and tablets) and an ever-expanding array of IoT devices (such as cameras, door locks, doorbells, refrigerators, audio/visual systems, thermostats, and various sensors) that communicate with one another.
List the four(4) purposes of a network
Resource Sharing - The goal is to make all programs, equipment(like printers, cctvs, etc), and especially data, available to anyone on the network without regard to the physical location of the resource and the user.
Communication - A computer network can provide a powerful communication medium among employees. Virtually every company that has two or more computers now has e-mail (electronic mail), which employees generally use for a great deal of daily communication
eCommerce - to become more important in businesses is doing business with consumers over the Internet. Airlines, bookstores and music vendors have discovered that many customers like the convenience of shopping from home. This sector is expected to grow quickly in the future.
Data Centralization - Data can be stored on one server instead of several devices. For example, on a small home network, all the data can be centralized by using a server. By doing this, anyone with access to the network can work with the data stored on the central server without needing to connect several external hard drives or flash drives to a computer.
Elements of communication in a computer network
The different components of Data communication are shown in the following figure.
1. Message:
The message is the information (data) to be communicated. Popular forms of information include text, numbers, pictures, audio, and video.
2. Sender:
The sender is the device that sends the data message. It can be a computer, workstation, telephone handset, video camera, and so on.
3. Receiver:
The receiver is the device that receives the message. It can be a computer, workstation, telephone handset, television, and so on.
4. Transmission medium:
The transmission medium is the physical path by which a message travels from sender to receiver. Some examples of transmission media include twisted-pair wire, coaxial cable, fiber-optic cable, and radio waves.
5. Protocol:
A protocol is a set of rules that govern data communications. It represents an agreement between the communicating devices. Without a protocol, two devices may be connected but not communicating, just as a person speaking French cannot be understood by a person who speaks only Japanese.
If we think of a network as roads, highways, rails, and other means of transport, the network protocols are the "traffic rules." The network protocols define how two devices in the network communicate.
The two(2) types of network
Networks are divided into two types, a LAN (Local Area Network) or a WAN (Wide Area Network), which are generic terms referring to two important basic types of networks.
Local Area Networks (LAN) is widely used to share resources and exchange information by connecting personal computers and workstations in company office and factories. A LAN is a network that is limited to an area such as a building or school. In a LAN, computers and hardware such as printers can be connected by cable (copper wiring), fiber optic cabling (glass fibers) or using a wireless (radio waves) connection.
Advantages of LANs:
Hardware such as printers can be shared so individual workstations do not need their own printer. When they print, the data is stored in a queue on a server. The data is then passed to the printer.
All the users work can be stored in a central place (the dedicated file server) so a user can access their work through any computer on the network.
Software can be shared, software packages are stored on the server and downloaded to workstations as requested. Note that a licence still has to be bought for each copy of the software needed.
Data can be shared because database files stored in the server are available to users around the network; data from CD-ROMs can also be shared across the network.
Central back-up can take place automatically at regular intervals. A user will usually be able to retrieve work that has been deleted by mistake.
Messages can be sent to people working at other computers on the network which can save time and paper.
It is possible to set up a local intranet such as that on the KLB school network. The web pages of information can be accessed only over the LAN. An intranet is free because it does not involve phone links.
There is control over users’ access rights to programs and data.
Disadvantages of LANs:
Printing can be slow. Where a lot of workstations are served by only one or two printers, long print queues may develop.
A virus can spread more easily. If a virus gets into one computer, it is likely to spread quickly across the network because it will get into the central backing store.
As data is shared there is a greater need for security. Users of the network have to have authentication techniques such as user ids and passwords. Unique user ID’s control access to the files and settings on the network while passwords prevent unauthorised users from logging onto the network. Data may also have to be encrypted so that it is meaningless if intercepted.
If the server fails, all the workstations are affected. Work stored on shared hard disk drives will not be accessible and it will not be possible to use network printers either.
The cost of installing the equipment is greater. Cabling can be expensive to buy and to install.
Damage to cables can isolate computers. Some sections of the network can become isolated and will not be able to communicate with the rest of the network.
Because networks can be complicated to maintain, a network manager may be need to be employed to run the system.
A Wide Area Network (WAN) is not confined to one building. The computers and terminals forming part of the network can be spread around the world. External communication links such as satellites, microwaves, and telecommunication links and optical fibre will be used to connect the parts of a WAN. The connection must normally be paid for because the links are external.
The Internet is a worldwide WAN and a LAN can be connected to it using a router.
Advantages of WANs:
These are similar to those of LAN’s except the scale of sharing etc. becomes far greater and can be world-wide.
Disadvantages of WANs:
Again these are similar to those of LAN’s except that issues such as security become even more important as potential hackers could break into a computer system from anywhere in the world rather than having to physically be in a building.
Encryption of secure data such as financial transactions is necessary because it is even easier to intercept data.
SECURING NETWORKED INFORMATION
Isa sa maiuugnay na husay ng seguridad ng isang computer network ay ang pagkakaroon nito ng AUTHENTICATION MECHANISMS. Karamihan ng computer networks ay dumedepende sa username and passwords para sa authentication, at may iba naman na mas advanced pa sa mga ito gaya ng biometric device na gumagamit ng physical na bahagi ng isang tao gaya ng fingerprint or retinal scan
Page updated
Report abuse