Computers Semester 1 Grade 8

Advantages of Ring topology

- Easier to find faults in network - More nodes can be added easily - Less number of cables are required

Disadvantages of Client Server Network

- A network operating system is needed - The server is expensive - Staff specializing in network management is needed - If any part of the network fails, disturbance occurs

Advantages of Client Server Network

- All files are stored in 1 place - The users can access shared data - All the peripherals are controlled centrally - Backup is maintained - Network security is controlled centrally

Advantages of Star topology

- Easy to add and remove notes - Reliable - Good network security as 2 nodes can't communicate without going through the server

Advantages of Bus topology

- Easy to install - Easy to add nodes - Uses less cable compared to other network topologies

Disadvantages of star topology

- Expensive - Failure of central hub will stop the entire network from working - Extra hubs or switches might be required

Disadvantages of ring topology

- If 1 node is switched off, network wont work - If 1 cable is faulty, network shuts down - Since the data passes through every computer, it reaches late to its destination

Advantages of peer-to-peer network

- It doesn't need a network operating system - It doesn't need an expensive server - It's much easier to set and maintain and so doesn't need a specialized staff. - If 1 computer fails, it doesn't disturb the work of others.

Disadvantages of Bus topology

- Problem in backbone results in entire network to stop working - Difficult to identify the problem if the entire network stops working - Too many nodes will result in the data sharing to be slow

Disadvantages of peer-to-peer network

- When each computer is accessible to other users, this might slow down the performance - Files aren't centrally backed up causing loss of data - Files can be difficult to find or search for - There are security issues.

Switch

A switch in a network transfers data to a specific computer.

Types of network;

Computer networks can be classified on a basis of geographical spread. -Local Area Networks(LAN) -Personal Area Networks(PAN) -Metropolitan Area Network(MAN) -Wide Area Network(WAN)

Transmission Media

Computers in a network can be wired or wireless. The various types of transmission medium are; Twisted pain cable, coaxial cable, Optical fibre, Radio Link, Satellite link and Infrared Transmission.

Ethernet Network Interface Card

Ethernet is a networking technology. It's used in LAN and MAN networks. Ethernet cards are used to connect a computer to another computer or to a server by using a cable. The computers on Ethernet install a special card called Ethernet card, which is sometimes known as Network Interface Card(NIC). It's used to transmit data from the network to your computer using a network cable. The cable connection on the card is an RJ-45 connection.

What are the disadvantages of a computer network?

If something is wrong with the server, users can't run applications. If the network is faulty, devices connected to it wont work. If a lot of people are using the network at once, the transfer and sharing of files will become slow.

Describe WAN

In Wide Are Network(WAN) the computers in a network are spread across the cities, countries or continents. It facilitates efficient exchange of information at a high speed. The Internet and ATMs are examples of WAN.

Client Server Network

In this network, a single powerful computer acts a server. It's connected to multiple computers called clients. The servers stores all the files, database and complex apps. The server serves its clients by answering and providing results to the queries raised by clients. It also controls the access to hardware, software and other resources. For example, when you access your bank account from a computer, the client program will raise a request to the server program at bank. The server will process on the specific account and send back the request on the machine with the required details.

Peer-to-Peer Network

In this network, each computer has equivalent capabilities and responsibilities. These computers are connected in a network but don't have a server. The printer can be connected to a computer which is accessible to other computers. For example, 2 or more people with their computers to share files directly with one another.

Ring topology

In this, each node in the network is connected to 2 other nodes in the network. The 1st and last node connected to each other forms a ring. All data passes from one node to the next node in a circle until it reaches its destination. The data mostly flows in a single direction only.

Repeater

It's a device that renews the incoming signal. Then it places the same on the communication channel again. It's used to increase the length of a network.

Bridge

It's a device that's used to link 2 same networks. It reduces the amount of traffic on LAN as it doesn't send all the data packets. It can be programmed to reject packets from particular networks.

Radio Link

It's a wireless interface. It's used by cellular networks like GSM and CDMA. The transmission is made by radio frequencies. The transmitter and receiver are used to encode and decode the data transmitted and received respectively. It's cheaper than buying maintaining cables, but when weather conditions change, it make the data transfer difficult.

Infrared Transmission

It's a wireless medium of transmission. An infrared beam is used to replace the cables between different rooms. This is suitable for offices where position of communication devices are changed constantly. T.V. remotes and wireless speakers use infrared as a transmission mediums.

Modem

It's derived from the word modular-demodulator. It converts the digital signals from the computer to another form that can be transmitted over telephone wires, and visa- versa.

What are the advantages of a computer network?

It's quick and easy. All the data is in one server so you don't need to upload, update and track files on independent computers. Resources like printers, scanners and modems can be shared in a network which saves space and money against buying too many resources. The cost of hardware for individual devices is reduced and it's secure; not everyone will have access to important files that are password protected, only specific people do.

Coaxial Cable

It's rigid or flexible. It's data transmission characteristics are much better than the Twisted pair cables. It's used by telephone companies, from their central offices to telephone poles near users. It's also used for LAN.

Hub

It's the most basic networking device that connects many computers or other network devices together. It's a single point of connection for devices in a network. It connects segments of a LAN. The NIC transfers data from a computer to a hub, which then transfers it to other connected computers.

Twisted Pain Cable

It's the most common form of wiring. It consists of 2 insulated copper wired twisted together. It can cover a long distance, is simple, flexible, weigh less and can be handled easily. Installation is easy and cheap.

Star topology

It's the most common network topology. Each node is connected to a central point link called hub or server. through this server, the drop cables extend in all directions. The data is transmitted between nodes in the network through this central node. It retransmits data to other nodes in the network. It's more reliable and used in offices and schools.

Bus Topology

It's the simplest of all the network topologies. The arrangement consists of a long communication channel(backbone) which connects all the nodes, printer and the server through small cable segments called drop cables. Both ends of a backbone cable are terminated.

Optical Fibre

It's used for data transmission over long distances(communication).It's also used as a medium for networking. The fibre of the wires is made of transparent plastic, glass or sometimes, both.

Gateway

It's used to connect 2 networks of different types. It acts as an entrance to another network. It can translate information into a format that is understood by another network. It can be implemented as software, hardware or both.

Router

It's used to forward data packets to other network when the destination address is outside its network. This process is known as routing. It supports different WAN technologies. The most common example is a home router that's used to share broadband internet connection.

Describe LAN

Local area network (LAN) is a network in a confined area like an office, building or collage campus. It's main purpose is to share resources, which can be hardware resources like printers, plotters, hard disks and modems, or soft resources like data, information and programs.

Describe MAN

Metropolitan Area Network(MAN) is a network spread over an entire city. Some examples of MAN are cable television, branches of a school/office/bank in the same city, and so on. It's owned by a single entity, like an organization.

Network Architecture

Network architecture means the design of a computer network. The 2 main types of network architecture are Client Server network and Peer-to-Peer network.

Who uses networks?

Network is very useful to the users who are working in large organizations or where the buildings are spread out. They can easily share files and hardware resources.

Describe PAN

Personal Area Network(PAN) is a computer network organized around an individual person. It usually involves a laptop, tablet or mobile phone. You can use these devices to transfer files like calendar appointments, digital photos and music. They are connected through wired or wireless connections. PAN covers a range of around 10m. Wireless PAN use Bluetooth or sometimes infrared connections. Bluetooth PANs are A.K.A piconets.

RJ-45

Registered Jack-45 is commonly used for computer network cables.

Network devices

Some of the network devices are required to connect computers and peripherals in a network are; Modem RJ-45, Ethernet, Hub, Switch, Repair, Bridge, Router and Gateway.

Node

The computer network is called a node. Each node is connected through cables, telephone lines, radio waves or infrared light.

Intranet

The network specific to the users within the organization is called the Intranet. It's a huge network and it's open to all.

Satellite Link

The satellite is placed above the surface of the Earth. It's function us to receive data from the Earth station and transmit the data to another station on Earth. The transmission in T.V. requires a satellite as a medium.

Network Topology

Topology is the arrangement of nodes connected to one another in a network. The way in which the nodes are connected depend on a number of factors, like arrangement, cost, flexibility and reliability. Arrangement(distance from 1 node to another); Nodes should be connected with minimum distance to reduce the total cost of networking Topology design should be flexible accommodate changes in the system. Insertion of new nodes should be easy. Reliability means fault- free working of the network. If 1 node fails, network performance shouldn't be affected. Some common network topologies are Bus topology, Star topology and Ring topology.

Network

When 2 or more computers or peripherals are connected together for sharing data or hardware resources, they form a network. Networks may vary in size, complexity and geographical speed.