Computer Networks POWERPOINT Presentation

Introduction

Computer networks are the backbone of modern communication and information systems. They allow computers to connect, share resources, and exchange data, forming the foundation for services such as the internet, email, and cloud computing. The principles of computer networks encompass a wide range of concepts, including network architecture, protocols, data transmission, security, and management. Understanding these principles is essential for designing, implementing, and maintaining effective and secure networks.

1. Network Architecture

Network architecture refers to the overall design of a computer network, including its physical and logical components. The architecture defines how different network devices (such as routers, switches, and servers) are interconnected and how data flows between them. There are several types of network architectures, including:

Client-Server Architecture: In this model, clients (end-user devices like computers and smartphones) request services from a central server that provides resources or data.
Peer-to-Peer (P2P) Architecture: In a P2P network, each device can act as both a client and a server, sharing resources directly with other devices without a central server.
Hybrid Architecture: This combines elements of both client-server and P2P architectures, often used in modern networks to optimize performance and resource sharing.
2. Types of Networks

Computer networks can be classified based on their size, geographic scope, and the technologies they use. The main types include:

Local Area Network (LAN): A LAN is a network that connects devices within a limited area, such as a single building or campus. LANs are typically used for internal communication and resource sharing within organizations.
Wide Area Network (WAN): A WAN covers a larger geographic area, often spanning cities, countries, or even continents. The internet is the most extensive example of a WAN. WANs connect multiple LANs and other networks.
Metropolitan Area Network (MAN): A MAN is larger than a LAN but smaller than a WAN, typically covering a city or large campus.
Personal Area Network (PAN): A PAN is a small network that connects devices in a personal workspace, such as a Bluetooth connection between a smartphone and a laptop.
3. Network Topologies

Network topology refers to the physical or logical arrangement of devices in a network. The topology determines how data is transmitted and how devices interact. Common network topologies include:

Bus Topology: All devices are connected to a single central cable (the bus). Data sent by one device is available to all others, but only the intended recipient processes it. Bus topology is simple but can be prone to collisions and faults.
Star Topology: Devices are connected to a central hub or switch. The hub/switch manages data transmission and directs data to the correct device. Star topology is reliable and easy to manage but can be expensive due to the extra cabling.
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1. Computer Networks

2.  A computer network is an interconnection of two or more computers that are able to exchange information.  The computer may be connected via any data communication link, like copper wires, radio links, etc.  They may be personal computers or large main frames.

3.  The computer network may be located in a room, building, city, country, or anywhere in the world.  Computer networks have opened up an entire frontier in the world of computing called the client/server model.

4.  FI L E S H A R IN G – Netw o r k s offe r a q u ic k and easy way to share files directly. RE S O U R C E SH ARIN G – A l l co m p u ter s i n the ca n sh a re fax machines, scanners, reso u r ce s su c h as and network printers, m o d e ms.  COMMUNICATION –Those on the network can communicate with each other via e-mail, instant messages, etc.

5.  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.

6. The different types of network are based on following: S i z e o f th e n e tw o r k – Refer s t o t he are a ov e r which the network is spread. Connection – Refers to the transmission media and protocols used for connecting. Network topology – Arrangement of computers on the network.

7. ON THE BASIS OF SIZE

8.  LAN is a computer network widely used for local communication.  LAN connects computers in a small area like a room, building, office, or a campus spread up to a few kilometers.  They are privately owned networks, to exchange information.

9.  Star, Bus, and Ring are some of the common LAN networking topologies.  LAN runs at a speed of 10 mbps to 100 mbps and has low delays.  A LAN based on wifi wireless network technology is called wireless local area network(WLAN).

10. METROPOLITIAN AREA NET W ORK (MAN)

11.  MAN is a computer network spread over a city. The computers in a MAN are connected using cables.  MAN connects several LAN spread over a city.  It covers the distance upto 30-50 km.  Example- Cable television network.

12. WIDE AREA NET W ORK (WAN)

13.  WAN is a network that connects computers over long distances like cities, countries, continents or world wide.  WAN uses public, leased, or private communication links to spread over long distances.  WAN uses telephone lines, satellite link and radio link to connect.

14.  The need to be able to connect any number of computers at any number of sites, results in WAN technology to be different from the LAN technology.  It is slower and less reliable than a LAN.  INTERNET is a common example of WAN.

15. I t i s t h e ph ysical way i n which com p uters are interconnected. Five basic network structures are :

16. D e v i ce s ar e co n n e cte d t o a ce n tr a l co m p u ter called HUB .  A Star network is particularly appropriate for organizations that require a centralized data base or a centralized processing facility.  For example, a star network may be used in banking for centralized record keeping in an on-line branch office environment.

17.  It is easy to add new and remove nodes.  A node fail u r e doe s n o t brin g le t down the entire network.  It is easier to diagnose network problems through a central hub.

18.  If the central hub fails, the whole network ceases to function.  It costs more to cable a star configuration than other topologies because more cable is required than other topologies.

19.  In Bus topology a single network cable runs in the building or campus and all nodes are linked along with this communication line with two endpoints called the bus or backbone.  Thi s s tr uct u r e i s very po p ul a r f o r l o c a l area networks

20.  R e lia b l e i n very small net wo r k s as well as easy to use and understand.  Requires the least amount of cable to connect the computers together and therefore is less expensive than other cabling arrangements.

21.  Hea v y netw o r k t raffi c ca n s lo w a bus considerably.  Each connection between cables weakens the electrical signal.

22.  In Ring topology the network cable passes from one node to another until all nodes are connected in the form of a “loop or ring”.  Transmits in only one direction.  Used in LAN’S and WAN’S.

23.  R in g n et w ork s ca n s p a n lo n g e r d ist a nc e s than other types of networks.  Ring networks are easily extendable.

24.  Relatively expensive and difficult to install.  Failur e o f on e compute r o n t he ne t w o r k can affect the whole network.  Adding or removing computers can disrupt the network.

25.  In mesh network, there is random connection of nodes using communication links.  M esh to p ol o gy i s th e g e ner a l t op o l o gy for wide area network.  A me s h net wor k ma y b e fully conn e c te d or connected with only partial links.

26.  The reliability is very high as there are always alternate paths available if direct link between two nodes is down.  Yields the greatest amount of redundancy in the event that one of the nodes fails where network traffic can be redirected to another node.

27.  The cost of installation and maintenance is high ( more cable is required than any other configuration).

28.  A tree topology connects one star network to the other star network.  It is an extension of star topology.  Here, we divided the whole network into segment which can be easily managed and maintained.

29.  Each segment is provided with dedicated point-to-point wiring to central hub.  Error detection and correction is easy.  If one segment is damaged, other segment are not affected.  Expansion of network is possible and easy.

30.  As multiple segments are connected to a central hub, the networks depend heavily on the hub. Its failure affects the entire network.  Maintenance is not easy and cost are high.  With increase in size beyond a point, the management becomes difficult.

31.  A network protocol defines rules and conventions for communication between network devices.  Protocols specify interactions between the communicating entities.

32. Protocol has Five types- TCP (Transmission Control Protocol) IP (Internet Protocol) HTTP (Hyper Text Transfer Protocol) FTP (File Transfer Protocol) HTTPS (Hyper Text Transfer Protocol Secure)

33.  It provides reliable transport service i.e. it ensures that messages sent from sender to receiver are properly routed and arrive at the destination.  TCP converts messages into a set of packages at the source which are then reassemble back into messages at the destination. For this, TCP operates with the packet switching techniques.

34. Packet Switching Techniques –  The message is divided into small packets.  Each p a ck e t co nt ain s a d d res s and information.  The address is used to route the packet to its destination .

35. diff e ren t c om puters to  IP allows communicat e.  IP handles the dispatch of packets over the network.  It handles the addressing of packets, and ensures that a packet reaches its destination travelling through multiple networks.

36. TCP/IP protocol makes it possible for any pair of computers connected to internet to communicate, despite their hardware differences.

37.  The File Transfer Protocol (FTP) is a standard network protocol used to transfer computer files from one host to another.  FT P i s b u il t o n c lien t s e rv e r architecture.

38. HTTP is the underlying protocol used by the World Wide Web. HTTP defines how messages are formatted and transmitted and what actions web servers and browsers should take in response to various commands.

39.  For example, when you enter a URL in your browser, this actually sends an HTTP commands to the Web server directing it to fetch and transmit the requested Web page.

40.  HTTPS stands for Hyper Text Transfer Protocol over SSL(Secure Socket Layer). It is used by Web servers to transfer and display web content securely.  HTTPS used by any website that is collecting sensitive customer data such as banking information or purchasing information

41. HUB REPEA T ER BRIDGE ROUTER GATEWAY

42. A hub is a multiport connecting device that is used to interconnect LAN devices.  A hub can be used to extend the physical length of a network.

43. Repeater boost or amplifies the signal before passing it through to the next section of cable.

44.  It connects the network with same protocol and topology.  The main task of a bridge computer is to receive and pass data from one LAN to another.

45.  A router is a device that connects multiple networks using similar or different protocols.  Routers are used when several networks are connected together.

46.  Gateway is a device that connects two or more networks with different types of protocol.  It receives data from one network and converts it according to the protocol of other network.