Week-1-Introduction-to-Computer-Network.pdf

NETWORKING 1: WEEK 1 Introduction to Computer Network OBJECTIVE: At the end of the lesson, the learner should be able to: 1. Explain what is data communication and networks. 2. Explain what computer network is. 3. Explain the different architecture of computer network. 4. Explain w...

NETWORKING 1: WEEK 1 Introduction to Computer Network OBJECTIVE: At the end of the lesson, the learner should be able to: 1. Explain what is data communication and networks. 2. Explain what computer network is. 3. Explain the different architecture of computer network. 4. Explain what are the components of computer network What is Computer Network? Computer Network is a group of computers connected with each other through wires, optical fibers or optical links so that various devices can interact with each other through a network. Classification of Computer Networks Computer networks are classified based on various factors. They include: Geographical span Inter-connectivity Administration Architecture Classification of Computer Networks 1. Geographical Span - Geographically a network can be seen in one of the following categories: It may be spanned across your table, among Bluetooth enabled devices, Ranging not more than few meters. Classification of Computer Networks It may be spanned across a whole building, including intermediate devices to connect all floors. It may be spanned across a whole city. It may be spanned across multiple cities or provinces. It may be one network covering whole world. Classification of Computer Networks 2. Inter-Connectivity - Components of a network can be connected to each other differently in some fashion. By connectedness we mean either logically, physically, or both ways. Every single device can be connected to every other device on network, making the network mesh. All devices can be connected to a single medium but geographically disconnected, created bus-like structure. Classification of Computer Networks Each device is connected to its left and right peers only, creating linear structure. All devices connected together with a single device, creating star-like structure. All devices connected arbitrarily using all previous ways to connect each other, resulting in a hybrid structure. Classification of Computer Networks 3. Administration - From an administrator’s point of view, a network can be private network which belongs a single autonomous system and cannot be accessed outside its physical or logical domain. A network can be public, which is accessed by all. Classification of Computer Networks 4. Network Architecture - Computer networks can be discriminated into various types such as Client- Server, peer-to-peer or hybrid, depending upon its architecture. There can be one or more systems acting as Server. Other being Client, requests the Server to serve requests. Server takes and processes request on behalf of Clients. Classification of Computer Networks Two systems can be connected Point-to-Point, or in back-to-back fashion. They both reside at the same level and called peers. There can be hybrid network which involves network architecture of both the above types. Classification of Computer Networks Network Applications - Computer systems and peripherals are connected to form a network. They provide numerous advantages: Resource sharing such as printers and storage devices Exchange of information by means of e-Mails and FTP Components of Computer Network NIC (Network Interface Card) - NIC is a device that helps the computer to communicate with another device. The network interface card contains the hardware addresses, the data-link layer protocol use this address to identify the system on the network so that it transfers the data to the correct destination. Components of Computer Network There are two types of NIC: wireless NIC and wired NIC. Wireless NIC: All the modern laptops use the wireless NIC. In Wireless NIC, a connection is made using the antenna that employs the radio wave technology. Wired NIC: Cables use the wired NIC to transfer the data over the medium. Components of Computer Network 2. Hub - Hub is a central device that splits the network connection into multiple devices. When computer requests for information from a computer, it sends the request to the Hub. Hub distributes this request to all the interconnected computers. Components of Computer Network 3. Switches - Switch is a networking device that groups all the devices over the network to transfer the data to another device. A switch is better than Hub as it does not broadcast the message over the network, i.e., it sends the message to the device for which it belongs to. Therefore, we can say that switch sends the message directly from source to the destination. Components of Computer Network 4. Cables and Connectors - Cable is a transmission media that transmits the communication signals. There are three types of cables: 1. Twisted pair cable: It is a high-speed cable that transmits the data over 1Gbps or more. 2. Coaxial cable: Coaxial cable resembles like a TV installation cable. Coaxial cable is more expensive than twisted pair cable, but it provides the high data transmission speed. Components of Computer Network 3. Fiber optic cable: Fiber optic cable is a high- speed cable that transmits the data using light beams. It provides high data transmission speed as compared to other cables. It is more expensive as compared to other cables, so it is installed at the government level. Components of Computer Network 5. Router - Router is a device that connects the LAN to the internet. The router is mainly used to connect the distinct networks or connect the internet to multiple computers. 6. Modem - Modem connects the computer to the internet over the existing telephone line. A modem is not integrated with the computer motherboard. A modem is a separate part on the PC slot found on the motherboard. Uses of Computer Network Resource sharing: Resource sharing is the sharing of resources such as programs, printers, and data among the users on the network without the requirement of the physical location of the resource and user. Server-Client model: Computer networking is used in the server-client model. A server is a central computer used to store the information and maintained by the system administrator. Clients are the machines used to access the information stored in the server remotely. Uses of Computer Network Communication medium: Computer network behaves as a communication medium among the users. For example, a company contains more than one computer has an email system which the employees use for daily communication. E-commerce: Computer network is also important in businesses. We can do the business over the internet. For example, amazon.com is doing their business over the internet, i.e., they are doing their business over the internet. Features of Computer network 1. Communication speed 2. File sharing 3. Back up and Roll back is easy 4. Software and Hardware sharing 5. Security 6. Reliability 7. Scalability Features of Computer network 1. Communication speed - Network provides us to communicate over the network in a fast and efficient manner. For example, we can do video conferencing, email messaging, etc. over the internet. Therefore, the computer network is a great way to share our knowledge and ideas. 2. File sharing - File sharing is one of the major advantages of the computer network. Computer network provides us to share the files with each other. Features of Computer network 3. Back up and Roll back is easy - Since the files are stored in the main server which is centrally located. Therefore, it is easy to take the back up from the main server. 4. Software and Hardware sharing - We can install the applications on the main server, therefore, the user can access the applications centrally. So, we do not need to install the software on every machine. Similarly, hardware can also be shared. Features of Computer network 5. Security - Network allows the security by ensuring that the user has the right to access the certain files and applications. 6. Reliability - Computer network can use the alternative source for the data communication in case of any hardware failure. Features of Computer network 7. Scalability - Scalability means that we can add the new components on the network. Network must be scalable so that we can extend the network by adding new devices. But, it decreases the speed of the connection and data of the transmission speed also decreases, this increases the chances of error occurring. This problem can be overcome by using the routing or switching devices. Computer Network Architecture Computer Network Architecture is defined as the physical and logical design of the software, hardware, protocols, and media of the transmission of data. Simply we can say that how computers are organized and how tasks are allocated to the computer. The two types of network architectures are used: Peer-To-Peer network Client/Server network The two types of network architectures are used: 1. Peer-To-Peer network Peer-To-Peer network is a network in which all the computers are linked together with equal privilege and responsibilities for processing the data. Peer-To-Peer network is useful for small environments, usually up to 10 computers. Peer-To-Peer network has no dedicated server. Special permissions are assigned to each computer for sharing the resources, but this can lead to a problem if the computer with the resource is down. The two types of network architectures are used: Advantages of Peer-To-Peer Network: 1. It is less costly as it does not contain any dedicated server. 2. If one computer stops working but, other computers will not stop working. 3. It is easy to set up and maintain as each computer manages itself. Disadvantages of Peer-To-Peer Network: 1. In the case of Peer-To-Peer network, it does not contain the centralized system. Therefore, it cannot back up the data as the data is different in different locations. 2. It has a security issue as the device is managed itself. The two types of network architectures are used: 2. Client/Server Network Client/Server network is a network model designed for the end users called clients, to access the resources such as songs, video, etc. from a central computer known as Server. The central controller is known as a server while all other computers in the network are called clients. A server performs all the major operations such as security and network management. The two types of network architectures are used: A server is responsible for managing all the resources such as files, directories, printer, etc. All the clients communicate with each other through a server. For example, if client1 wants to send some data to client 2, then it first sends the request to the server for the permission. The server sends the response to the client 1 to initiate its communication with the client 2. The two types of network architectures are used: Advantages of Client/Server network: A Client/Server network contains the centralized system. Therefore we can back up the data easily. A Client/Server network has a dedicated server that improves the overall performance of the whole system. Security is better in Client/Server network as a single server administers the shared resources. It also increases the speed of the sharing resources. The two types of network architectures are used: Disadvantages of Client/Server network: Client/Server network is expensive as it requires the server with large memory. A server has a Network Operating System (NOS) to provide the resources to the clients, but the cost of NOS is very high. It requires a dedicated network administrator to manage all the resources. Thank you for listening Question and Answer