Introduction to Computer Networks

1. Introduction to Computer Networks Chapter 1 Introduction to computer network

2. Introduction to Computer Networks Networks • A network is a set of devices (often referred to as nodes) connected by communication links. A node can be a computer, printer, or any other device capable of sending and/or receiving data generated by other nodes on the network. By: Jigar M. Pandya

3. Introduction to Computer Networks Rules For Communication • Transmission should take place without error. • Transmission should be Less. • The cost of Transmission should be less. • The message should be safe and secure. Bu: Jigar M. Pandya

4. Introduction to Computer Networks 5 Components For Communication Bu: Jigar M. Pandya

5. Introduction to Computer Networks Data Flow Of Messages Bu: Jigar M. Pandya

6. Bu: Jigar M. Pandya Introduction to Computer Networks Applications of Networks • Resource Sharing • Hardware (computing resources, disks, printers) • Software (application software) • Information Sharing • Easy accessibility from anywhere (files, databases) • Search Capability (WWW) • Communication • Email • Message broadcast

7. Introduction to Computer Networks Network Topology • The network topology defines the way in which computers, printers, and other devices are connected. A network topology describes the layout of the wire and devices as well as the paths used by data transmissions. Bu: Jigar M. Pandya

8. Introduction to Computer Networks Bus Topology • Commonly referred to as a linear bus, all the devices on a bus topology are connected by one single cable. Bu: Jigar M. Pandya

9. Bu: Jigar M. Pandya Introduction to Computer Networks Star & Tree Topology • The star topology is the most commonly used architecture in Ethernet LANs. • Larger networks use the extended star topology also called tree topology. When used with network devices that filter frames or packets, like bridges, switches, and routers, this topology significantly reduces the traffic on the wires by sending packets only to the wires of the destination host.

10. Bu: Jigar M. Pandya Introduction to Computer Networks Ring Topology • A frame travels around the ring, stopping at each node. If a node wants to transmit data, it adds the data as well as the destination address to the frame. • The frame then continues around the ring until it finds the destination node, which takes the data out of the frame. • Single ring – All the devices on the network share a single cable • Dual ring – The dual ring topology allows data to be sent in both directions.

11. Introduction to Computer Networks Mesh Topology • The mesh topology connects all devices (nodes) to each other for redundancy and fault tolerance. • It is used in WANs to interconnect LANs and for mission critical networks like those used by banks and financial institutions. • Implementing the mesh topology is expensive and difficult. Bu: Jigar M. Pandya

12. Introduction to Computer Networks Types of Connection Bu: Jigar M. Pandya

13. Physical Media Interconnecting Devices Computers Networking Software Applications Bu: Jigar M. Pandya Introduction to Computer Networks Network Components

14. Bu: Jigar M. Pandya Introduction to Computer Networks LAN, MAN & WAN • Network in small geographical Area (Room, Building or a Campus) is called LAN (Local Area Network) • Network in a City is call MAN (Metropolitan Area Network) • Network spread geographically (Country or across Globe) is called WAN (Wide Area Network)

15. Introduction to Computer Networks Applications • E-mail • Searchable Data (Web Sites) • E-Commerce • News Groups • Internet Telephony (VoIP) • Video Conferencing • Chat Groups • Instant Messengers • Internet Radio Bu: Jigar M. Pandya

16. Network Models

17. Two Types Of Connections are there • Connection Oriented service • Connectionless service • Connection Oriented Service. • Similar to the telephone system • Establish Connection • Use Connection • Release connection. • Connectionless service. • Same as postal service, each message has full add. • Order may differ of delivery. • Five primitives are used. • Listen • Connect • Receive • Send • Disconnect

18. LAYERED TASKS We use the concept of layers in our daily life. As an example, let us consider two friends who communicate through postal mail. The process of sending a letter to a friend would be complex if there were no services available from the post office.

19. Tasks involved in sending a letter

20. THE OSI MODEL Established in 1947, the International Standards Organization (ISO) is a multinational body dedicated to worldwide agreement on international standards. An ISO standard that covers all aspects of network communications is the Open Systems Interconnection (OSI) model. It was first introduced in the late 1970s.

21. ISO is the organization.OSI is the model.

22. Seven layers of the OSI model

23. The interaction between layers in the OSI model

24. Physical layer The physical layer is responsible for movements of individual bits from one hop (node) to the next.

25. Data link layer The data link layer is responsible for moving frames from one hop (node) to the next.

26. Figure 2.7 Hop-to-hop delivery

27. Network layer The network layer is responsible for the delivery of individual packets from the source host to the destination host.

28. Transport layer The transport layer is responsible for the delivery of a message from one process to another.

29. Session layer The session layer is responsible for dialog control and synchronization.

30. Presentation layer The presentation layer is responsible for translation, compression, and encryption.

31. Presentation layer • Data translation ,compression and encryption. • Encrypt data to hide it. • Compress data from last message to small no of messages.

32. Application layer The application layer is responsible for providing services to the user.

33. Application layer • Login password checking, file transfer are some of the application. • Provide direct access to network device. • Interface between user and system.Examples • File transfer • Emails • www • Protocols • ftp, smtp, telnet….

34. Summary of layers

35. QUESTIONS What is Connection Oriented Service ? What Is Connection Less Service ? Example Of Connation Less ? Example Of Connection Oriented ? Full Form Of OSI Full Form OF ISO What is OSI Model ? How many Layers are there in OSI Model ? Task Of Application layer ? Task Of Presentation layer ? Task Of Session layer ? Task Of Transport layer ? Task Of Network layer ? Task Of Data-link layer ? Task Of Physical layer ?

36. TCP/IP Model The layers in the TCP/IP MODEL do not exactly match those in the OSI model. The original TCP/IP protocol suite was defined as having four layers: host-to-network, internet, transport, and application. However, when TCP/IP is compared to OSI, we can say that the TCP/IP protocol suite is made of five layers: physical, data link, network, transport, and application.

37. TCP/IP Model ( Transmission control protocol / internet protocol ) The TCP/IP reference model.

38. TCP/IP Model ( Transmission control protocol / internet protocol ) • IT Was earlier used by ARPA(Advanced Research Project Agency) • Used to connect Military networks together. • Basically work for the internet . • TCP/IP offers a simple naming and addressing scheme. • Info is carried in packets. • IP is used to put message in Packet. • Each packet has address of sender and receiver (IP Address) • Divide large message in to small packets. • It is not necessary for all packets to follow same route. • HTTP helps it to Share HTML Doc with the help of WWW.

39. TCP/IP Model Layers Host – to – Network Layer • Lowest Layer in model • Combination of Physical and Data-link Layer. • The host has to connect to the network using some protocol, so it can send IP packets over it. • Protocol may vary based on host or network.

40. TCP/IP Model Layers Internet Layer • It holds whole architecture together. • The task is to insert packet into any network and make them travel. • The order of packets may differ ,the higher layer support it to arrange packets. • It Defines Packet format and protocol called IP. • Routing of packets and congestion control are important issues. • Almost same as the network layer in OSI model.

41. TCP/IP Model Layers Transport Layer • Same Function as Transport layer in OSI layer. • It allows entities to converse with each other. • The Protocols Used Are TCP & UDP. • TCP is Connection Oriented Service, No Error ,Handles Flow of control. • UDP is Connection less service, Chances Of Error , Prompt delivery is more important then accurate.

42. TCP/IP Model Layers Application Layer • IT Doesn't Have Session or Presentation Layer. • All upper level protocols are supported by This layer. • Main task is to provide user interface. • Provide services that can be used by other services. • For Example . • SMTP :- Mailing Service • Telnet :- Remote Logon Service • FTP :- File Transfer Service.

43. TCP/IP and OSI model

44. Comparing OSI and TCP/IP Models • Concepts central to the OSI model • Services • Interfaces • Protocols

45. Comparing OSI and TCP/IP Models • Why OSI did not take over the world • Bad timing • Bad technology • Bad implementations • Bad politics

46. Comparing OSI and TCP/IP Models • Problems In TCP / IP : • Service, interface, and protocol not distinguished • Not a general model • Host-to-network “layer” not really a layer • No mention of physical and data link layers • Minor protocols deeply embedded, hard to replace

49. Hybrid Model

50. Design Issues For Layers • Addressing - whom am I going to talk to? i.e., how do we identify senders and receivers? • Rules for data transfer: Simplex ,half-duplex and full duplex • Error control: This is all about communicating along imperfect channels and error correction in such cases. • Large messages: Procedures for disassembling, transmitting and reassembling.