Lecture-03 - Introduction To Network.pptx

Explore the fundamentals of computing with 'Introduction to Computer'.

1. Introduction To Network By Md. Sakhawat Hossain

2. What is a computer network? A computer network , or data network , is a digital telecommunications network which allows nodes to share resources . In computer networks, computing devices exchange data with each other using connections (data links) between nodes. Two or more computers connected together through a communication medium to share resources is called computer network.

3. What is a computer network?

4. Why is a network needed? Network is nothing but a medium to transfer message or simply say data. let us clear this with a real life example, suppose you are travelling by your car from Dhaka to Khulna , in that scenario the road is a network and your car is the packet travelling through this network and you of course are the data enclosed in the packet.

5. Application Sharing of resources such as printers Sharing of expensive software's and database Communication from one computer to another computer Exchange of data and information among users via network Sharing of information over geographically wide areas.

6. Computer Network There are two types of computers used in computer network. Terminal/Node The computers, which take part in the activities of the network, are called terminal or node. Server It is a central computer in a network, which controls all the terminals of the network. It is used to fulfill all the requests from terminals.

7. Computer Network

8. Advantages of Computer Network

9. Advantages of Computer Network FILE SHARING – Networks offer a quick and easy way to share files directly. RESOURCE SHARING – All computers in the network can share resources such as printers, fax machines, scanners, and modems. COMMUNICATION –Those on the network can communicate with each other via e-mail, instant messages, etc. Flexible Access - Networks allow their users to access files from computers throughout the network. Sharing of Information - Computer networks enable us to share data and information with the computers that are located geographically large distance apart.

10. Types of Network Based on the size and the coverage area, networks are categorized into the following types: Personal Area Networks (PANs) Local Area Networks (LANs) Metropolitan Area Networks (MANs) Wide Area Networks (WANs) Campus Area Network (CANs)

11. Personal Area Networks (PANs) PAN stand for Personal Area Network . A personal area network (PAN) refers to the interconnection of information technology devices or gadgets within the environment of an individual user . Typically the range lies within 10 meters or 33 feet . These interconnected devices might include laptop computers, PDAs, cellphones, printers, PCs or other wearable computer devices.

12. Personal Area Networks (PANs) Also known as a wireless personal network (WPAN) Typically uses Bluetooth for connecting devices. NFC is a newly emerged type of PAN technology. PANs can be wired, such as USB or FireWire, or they can be wireless, such as Bluetooth and ultrawideband.

13. Personal Area Networks (PANs) What can personal networks are do? Wireless connections between PCs and peripherals can free up floor space , remove unwanted cables and liberate floor plans. Connected Bluetooth devices can automatically synchronize data downloads and uploads, and exchange information. Mobile employees can use Bluetooth-equipped devices to access office-based peripherals such as printers, if these support Bluetooth technology.

14. Personal Area Networks (PANs) Advantages and disadvantages: PANs are efficient, cost-effective and convenient . Some PANs can interact badly with other wireless networking technologies using the same radio bands. Bluetooth networks are relatively secure , but have slow data rates . Bluetooth is a short-range solution – up to ten meters - and is not suitable for wireless connection over larger distances.

15. Local Area Networks (LANs) A local area network (LAN) is a network that connects computers and devices in a limited geographical area such as a home, school, office building, or closely positioned group of buildings . Each computer or device on the network is a node . LAN connection speeds can be 10 Mbps or 100 Mbps or 1000 Mbps also. LAN uses Physical Media (Wired).

16. Local Area Networks (LANs) Advantages of LAN: The basic LAN implementation does not cost too much . It is easy to control and manage the entire LAN as it is available in one small region . The LAN configuration is very easy due to availability of required protocols in the Operating System (OS) itself. It is easy to share common resources such as printers and internet line among multiple LAN users.

17. Local Area Networks (LANs) Disadvantages of LAN LAN covers small geographical area . Security issues are big concern as it is easy to have access to programs and data of peers. Special security measures are needed to stop unauthorized access . It is difficult to setup and maintain LAN and requires skilled technicians and network administrators . In the server based LAN architecture, if server develops some fault, all the users are affected.

18. Metropolitan Area Networks (MANs) It is relatively larger than LAN and extends across a city or a metropolitan . It is created by connecting two or more LANs located at different locations in a city.

19. Metropolitan Area Networks (MANs) Advantages of MAN It utilizes drawbacks of both LAN and WAN to provide larger and controllable computer network. MAN requires fewer resources compare to WAN. This saves the implementation cost. It helps people interface fast LANs together. This is due to easy implementation of links. It provides higher security compare to WAN.

20. Metropolitan Area Networks (MANs) Disadvantages of MAN: It is difficult to manage the network once it becomes large. It is difficult to make the system secure from hackers and industrial espionage. Network installation requires skilled technicians and network administrators . This increases overall installation and management costs. It requires more cables for connection from one place to the other compare to LAN.

21. Metropolitan Area Networks (MANs )

22. Wide Area Networks (WANs) A Wide Area Network (WAN) is a computer network that covers a large geographic area such as a country or the world . One of the most prominent examples of the existing WAN is the Internet . Transmission Media Fibre Optic, Microwave transmission and Satellite.

23. Wide Area Networks (WANs) Advantages of WAN: WAN covers larger geographical area . Hence business offices situated at longer distances can easily communicate. Like LAN, it allows sharing of resources, application and software among distributed workstations or users . The software files are shared among all the users . Hence all will have access to latest files. Organizations can form their global integrated network through WAN. Moreover it supports global markets and global businesses .

24. Wide Area Networks (WANs) Disadvantages of WAN Initial investment costs are higher. It is difficult to maintain the network. It requires skilled technicians and network administrators. There are more errors and issues due to wide coverage and use of different technologies. Often it requires more time to resolve issues due to involvement of multiple wired and wireless technologies. It has lower security compare to LAN and MAN due to wider coverage and use of more technologies.

25. LAN - WAN-MAN

26. D ISTINGUISH BETWEEN LAN-WAN - MAN PARAMETERS LAN WAN MAN Ownership of network Private Private or public Private or public Geographical area covered Small Very large Moderate Design and maintenance Easy Not easy Not easy Communication medium Coaxial cable PSTN or satellite links Coaxial cables, PSTN, optical fibre, cables, wireless Bandwidth Low High moderate Data rates(speed) High Low moderate

27. Campus Area Network (CANs) The campus area network is made up of an interconnection of LAN with limited geographical area. Network equipment such as switches, routers and the transmission media i.e. optical fibre etc are almost entirely owned by the campus owner.

28. HOW ARE NETWORKS CATEGORIZED? Networks are usually classified using three properties: Architecture Topology Protocol

29. Classification of Network Architecture The architecture of a network is a logical design that determines how the devices in the network communicate. The commonly used architectures for computer networks are: Client-server architecture Peer-to-peer architecture Hybrid architecture

30. Classification of Network Architecture Client-server Architecture On a network built using the client-server architecture, the devices communicate to other devices through a central computer referred to as a server. The server is a terminal with high processing power , which provides services for the other computers on the network. The client is a terminal that accesses the resources available on a server.

31. Classification of Network Architecture Client-server Architecture

32. Classification of Network Architecture Peer-to-peer Architecture On a network built using the peer-to-peer architecture, no specific distinction exists between a client and a server. Any node can provide a service as well as send a  request for a service from another node on the network. The peer-to-peer network architecture allows sharing of resources, data, and users. Each node on the network has full control over the  network resources.

33. Classification of Network Architecture Peer-to-peer Architecture

34. Classification of Network Architecture Peer-to-peer Architecture

35. Classification of Network Architecture Hybrid Architecture A hybrid is a composition of two different types of elements. A hybrid network architecture is created to get the benefits of both , the peer-to-peer and the client-server architectures, in a network.

36. NETWORK TOPOLOGY The pattern of interconnection of nodes in a network is called the Topology. The physical topology of a network refers to the configuration of cables, computers and other peripherals. The different types of network topologies that can be used to set up a network are: Bus Topology Ring Topology Star Topology Mesh Topology Hybrid Topology

37. BUS TOPOLOGY The bus topology has each node connected to a main communication channel. If one node is faulty this has no effect on the rest of the network If the bus is faulty, the whole network is “down” Advantage = Easy to add new stations Disadvantage = Each node may have to compete with each other in order to transmit and receive data

38. RING TOPOLOGY Signals are sent around the network from node to node . Data travels in one direction . If one of the nodes on the network stops, the entire network stops functioning. If a communications channel fails, the network fails.

39. STAR TOPOLOGY All peripheral nodes are connected to a central node. If a peripheral node fails it has no effect on the network. If the central node fails the whole network is “ down ”. Advantage = Easy to add new stations Disadvantage = Central node may get congested with network traffic

40. MESH TOPOLOGY Each node is connected to more than one node . This provide an alternate route mechanism . Supports back-up and rerouting . This type topology generally use in military area . Advantage = A node failure has no effect on the rest of the network. Disadvantage = Expensive to set up with a lot of cabling.

41. HYBRID TOPOLOGY The hybrid topology can be a combination of two or more basic topologies , such as bus, ring, star, mesh, or tree. Hybrid networks combine more than two topologies, which, in turn, enable  you to get advantages of the constituent topologies.

42. Difference Bus Topology Ring Topology Star Topology Structure there is a single central cable (backbone) and all computers and other devices connect to it all computers and other devices are connected in a circle there is a central host and all nodes connect to it Host existence depends on network needs depends on network needs yes Connection between nodes It has no connection between the nodes. yes no Host failure network can still run network will fail network will fail Node failure network can still run network will fail network can still run Ease of tr o u bl e s h oo ti n g difficult. Need to search for the problematic node one by one depends on backbone. If there is a backbone, troubleshooting is difficult. If there is no backbone, the focus is on the two nodes not communicating depends on the host. It is easier to repair the problematic host. However, if the nodes fail, then each node has to be searched Ease of adding or removing nodes easy difficult average Number of nodes when extending network many limited limited

43. NETWORK PROTOCOLS A network protocol defines rules and conventions for communication between network devices. Protocols specify interactions between the communicating entities .

44. NETWORK PROTOCOLS Network Protocol has five types-

45. NETWORK PROTOCOLS File transfer protocol (FTP) – used to transmit files. Simple mail transfer protocol (SMTP) – used to transmit e-mail messages. Post office protocol (POP) – allows the recipient to retrieve messages. Wireless application protocol – enables wireless devices to access and use the Internet using a client/server network. 802.11 – protocol for wireless LAN technology

46. Thank You