NETWORKING

1. NETWORKING

2. COMPUTER NETWORKS • In this lesson you will learn • What is a network and what are its advantages? • What can be shared among the computers connected in a network? • What Are the advantages Of Networking? • What Are the types of Networks? • What are Components of a Network? • What are the categories of networks? • What are Server-Based Networks? • What are peer to peer Networks? • Where Peer-to-peer networks are suitable? • What are the features of both server based and peer-to-peer Networks?

3. What is a network and what are its advantages? • A Computer network is a communication system where a group of computers and other devices like printers are interconnected by cables and other hardware. The data residing in one computer can be shared between other computers. A network, besides facilitating data communication, allows resources (Files, sound bytes, printers etc.) to be shared among all the systems connected to the network.

4. Thus, users on the second floor of a building can use the printer on the eleventh floor if their computer and the printer are connected to the network. This concept of connected computers sharing resources is called networking. This is shown in Fig.

6. What can be shared among the computers connected in a network • Computers that are connected in a network can share : • Data like audio and other files of different formats • Messages • Printers • Hard Disks • CD-ROMs • Modems • Other hardware resources

7. What Are the advantages Of Networking? • Networks allow efficient management of resources. For example, multiple users can share a single high-quality printer, rather than having multiple, possibly lower quality printers on individual desktops. • Networks help keeping information reliable and up-to-date. A well-managed , centralized data storage system allows multiple users to access data from different locations Cont…

8. Networks help speed up data sharing. Transferring files across a network is always faster than other, non-network means of sharing files. • Services like electronic-mail being offered by computer networks, allows much more efficient communication among individuals.

9. 4. What Are the types of Networks? • Networks can be classified as follows : • a. Local Area Network (LAN) • If a network is confined to a single location, typically one building or complex, it is called a Local Area Network (LAN). The maximum distance from one end of a network to another is usually limited by the signal strength or the network systems built-in time limit for sending and receiving messages through a physical connection, such as a cable.

10. b. Wide Area Network (WAN) • As the advantages of networking become known, business saw the need to expand the networks. LANs could not adequately support the network needs of a large business, with offices and operations spread over a wide area. This led to the development of Wide Area Networks. • When a network is spread over wide areas, such as across cities, states or countries, it is called a Wide Area Network (WAN). Communication on a WAN takes place via telephone lines, satellites or microwave links, rather than through a physical cable.

11. c. Metropolitan Area Network (MAN) • In between LAN and WAN is the Metropolitan Area Network (MAN). A MAN is a network that covers an entire city, but uses LAN technology. Cable television networks are examples of MANs distributing television signals. The MANs we are interested in, carry information in the form of signals from one computer to another.

12. 5. What are Components of a Network? • The following are the components and features that all networks have in common • Servers – Computers that provide shared resources to network users. • Clients - Computers that access shared network resources provided by a server. • Media - The way in which the computers are connected. • Resources - Files, printers or other networks can be divided into two broad categories.

13. 6. What are the categories of networks? • Networks can be divided into two broad categories : • Server Based networks • Peer-to-Peer networks

14. 7. What are Server-Based Networks? • Most networks have a dedicated server. A dedicated server is a computer on a network that functions as a server, and is not used as a client or a workstation. A dedicated server is optimized to service requests from network clients.

15. Servers perform a wide variety of tasks. Usually, large networks have specialized servers for different tasks. Examples of specialized servers are : • File and print servers – manage user access and use of file and printer resources. • Application servers – make the data on the server available to clients. • Mail servers – manage electronic messaging between network users. • Communication servers – handle data flow and E-mail messages.

16. 8. What are Peer-to-Peer Networks? • In a peer-to-peer network, there are no dedicated servers. All the computers are equal and, therefore, are termed as peers. Normally, each computer functions as both a client and a server. • A peer-to-peer network has the advantage of simplicity in design and maintenance. It is usually less expensive to set up as compared to server based networks. Peer-to-peer networks are also called workgroups. The term workgroups implies a small group of users.

17. 9. Where Peer-to-peer networks are suitable? • Peer-to-peer networks are suitable for environments where : • There are limited users (usually 10 or less) • The users are located in the same area. • Security is not an important issue. • The organization and the network have limited growth. • Users need to freely access data and programs that reside on other computers across the network

18. In a peer-to-peer network, there is no one assigned as an administrator who is responsible for the entire network. Users administer their own computers. All users can share any of their resources. Note : Networkadministration involves tasks like managing users and security, making resource available, installing and upgrading software.

19. 10. What are the features of peer-to-peer and served-based networks.

20. A few lines regarding the networking model • Virtually all networks in use today are based on the Open Systems Interconnection (OSI) standard. OSI was developed in 1984 by the International Organization for Standardization (ISO), a global federation of national standards organizations representing approximately 130 countries. • The core of this standard is the OSI Reference Model, a set of seven layers that define the different stages that data must go through to travel from one device to another over a network.

21. The seven layers, which separate into two sets, are: • Application Set • Layer 7: Application - This is the layer that actually interacts with the operating system or application whenever the user chooses to transfer files, read messages or perform other network-related activities

22. Layer 6: Presentation - Layer 6 takes the data provided by the Application layer and converts it into a standard format that the other layers can understand. • Layer 5: Session - Layer 5 establishes, maintains and ends communication with the receiving device.

23. Transport Set • Layer 4: Transport - This layer maintains flow control of data and provides for error checking and recovery of data between the devices. Flow control means that the Transport layer looks to see if data is coming from more than one application and integrates each application's data into a single stream for the physical network

24. Layer 3: Network - The way that the data will be sent to the recipient device is determined in this layer. Logical protocols, routing and addressing are handled here. • Layer 2: Data - In this layer, the appropriate physical protocol is assigned to the data. Also, the type of network and the packet sequencing is defined.

25. Layer 1: Physical - This is the level of the actual hardware. It defines the physical characteristics of the network such as connections, voltage levels and timing.

26. Lesson Summary • In this lesson you had learnt • A network is inter connection of computers and other hardware devices. • Data and other hardware peripherals like CD-ROM, hard disk, printer can be shared among the users in a network. • The advantages Of Networking are it reduces the investment on hardware and software in an office and accessibility of resources from any point of network. • The types of Networks are LAN, WAN and MAN and its suitability to various environment

27. The Components of a Network like servers, clients, media and resources. • The categories of networks like server based and Peer-to peer network. • The Server-Based Networks used in a large network with one computer providing central authentication to users and computers and providing other services

28. Peer to peer Networks are suitable up to 10 computers and there will be no central authority and the users had to administer their computers. • All networks are based on OSI model developed by ISO. It consists of seven layers which are divided in to two set viz. Application set and Transport set.

29. Lesson 2Network topologies • In this lesson you will learn • The standard network topologies • What is a Bus Topology? • What is a Star Topology? • What is a Ring Topology? • The advantages and disadvantages of each type of topology. • Other Topologies being used

30. protocol • A set of rules and conventions* for sending information over a network. These rules govern the content, format, timing, sequencing, and error control of messages exchanged among network devices. *A generally accepted rule or practice based on custom, usage, etc.

31. Transmission Control Protocol/Internet Protocol (TCP/IP) • A set of networking protocols widely used on the Internet that provides communications across interconnected networks of computers with diverse* hardware architectures and various operating systems. TCP/IP includes standards for how computers communicate and conventions for connecting networks and routing traffic. * mixed

32. Internet Protocol (IP) • A routable protocol in the TCP/IP protocol suite that is responsible for IP addressing, routing, and the fragmentation and reassembly of IP packets Internet service provider (ISP) A company that provides individuals or companies access to the Internet and the World Wide Web. An ISP provides a telephone number, a user name, a password, and other connection information so users can connect their computers to the ISP's computers. An ISP typically charges a monthly or hourly connection fee.

41. 1. What are STANDARD TOPOLOGIES? • Networks can be configured in the following basic topologies : • Bus • Star • Ring

42. 2. What is a Bus Topology? • The bus topology is also known as linear bus, it consists of several computers which are attached to a common cable called the trunk line as in Fig.1. • In the bus topology, data on the network is sent to all the computers on the network. However, the data is accepted only by the computer that has the address matching the address in the signal. Only one computer at a time can send messages. Cont>>>

43. . The bus topology is a passive topology in which the computers on the bus are not responsible for moving data. In this, failure of one computer does not affect the performance of the network. The performance on a bus network can be affected by the following factors : • Number of computes on the network • Hardware capabilities of computers on the network • Frequency of data transmission • Types of cable used on the network • Distance between computers on the network.

44. Note : Every computer on the network has an unique address. It is known as IP address. Data that is sent from any computer contains the address of the recipient computer to which it is sent.

46. What is a Star Topology? • In the star topology, computers are connected by cable segments to a centralized device known as hub or switch as in Fig. 2. This configuration is very popular and is widely used. Signals are transmitted from the sending computer through the controller on the central hub to the receiving computer. As each computer is connected to a central point, this topology requires a great deal of cabling. Also, if the central controller fails, the entire network is disabled. However, if one computer, or the cable that connects it to the hub fails, the rest of the network continues to function normally.

48. 4. What is a Ring Topology? • In ring technology, computers are connected through a single circle of cable as shown in Fig. There are no terminated ends. The signals travel around the loop in one direction and pass through each computer. The ring is an active topology where each computer acts like a repeater to boost the signal, and sends it on to the next computer. Failure of one computer in a ring network can affect the entire network. This system suffers from disadvantages and is not widely used.

50. 5. List the advantages and disadvantages of each type of topology?