2. OSI means Open System Interconnect model. OSI means Open System Interconnect model. Developed by the International Organization for Standardization in 1974. Developed by the International Organization for Standardization in 1974. It consists of seven layers. It consists of seven layers. Each layer has a different but specific processing function. Each layer has a different but specific processing function. OSI Model

3. Advice Person Sales Take Not DoDo Please OSI Model Layers Application Presentation Session Transport Network Data Link Physical Layer - 7 Layer - 6 Layer - 5 Layer - 4 Layer - 3 Layer - 2 Layer - 1 Upper Layer or Software Layer Lower Layer or Hardware Layer Heart of OSI

4. Application Layer Application Layer is responsible for providing Networking Services to user. It also known as Desktop Layer. Identification of Services is done using Port Numbers. Ports are nothing but Socket i.e. Entry and Exit Point to the Layer Total No. Ports 0 – 65535 Reserved Ports 0 – 1023 Open Ports 1024 – 65535 Application Presentation Session Transport Network Data Link Physical Application

5. Example of HTTP request ClientWeb Server http://www.zoomgroup.com

6. Example of HTTP request ClientWeb Server HTTP Request http:// www.zoomgroup.com Webpage HTTP Request Listen on Port 80 Sending HTTP Reply Webpage Received HTTP Reply http://www.zoomgroup.com Webpage

7. Example of FTP request ClientFTP Server ftp://ftp.microsoft.com

8. Example of FTP request FTP Request ftp://ftp.microsoft.com FTP Request Listen on Port 21 Sending FTP Reply Received FTP Reply ftp://ftp.microsoft.com ClientFTP Server

9. Examples of Networking Services Service Port No. HTTP80 FTP21 SMTP 25 TELNET23 TFTP69

10. Application 218025675369 How data flows from Application Layer Data Presentation Session Transport Network Data Link Physical

11. Presentation Layer Presentation Layer is responsible for converting data into standard format. Examples : ASCII, EBCDIC, JPEG, MPEG, BMP, MIDI, WAV, MP3 Following tasks are perform at Presentation layer : Encoding – Decoding Encryption – Decryption Compression – Decompression Application Presentation Session Transport Network Data Link Physical Presentation

12. How data flows from Presentation Layer Data Application Presentation Session Transport Network Data Link Physical

13. Session Layer Session Layer is responsible establishing, maintaining and terminating session. Session ID also works at Session Layer. Examples : RPC  Remote Procedure Call SQL  Structured Query language NFS  Network File System Application Presentation Session Transport Network Data Link Physical Session

14. How data flows from Session Layer Data Application Presentation Session Transport Network Data Link Physical

15. Transport Layer Transport Layer is responsible for end-to-end connectivity. It is also known as heart of OSI Layers. Following task are performed at Transport Layer : - Identifying Service Multiplexing & De-multiplexing Segmentation Sequencing & Reassembling Flow Control Error Correction Application Presentation Session Transport Network Data Link Physical Transport

16. Identifying Service Transmission Control Protocol Connection Oriented Acknowledgement Reliable Slower Port No. 6 e.g. HTTP, FTP, SMTP User Datagram Protocol Connection Less No Acknowledgement Unreliable Faster Port No. 17 e.g. DNS, DHCP, TFTP TCPUDP

17. Application Presentation Session Multiplexing & De-multiplexing 218025675369 Transport TCP - 6UDP - 17 Network Data Link Physical

18. Segmentation Hello! How are you ? Hello!HowAreYou? Hello! How are you ? AB

19. Sequencing & Reassembling Hello! How are you ? Hello! How AreYou? Hello! How are you ? AB You Hello! How ? Are Hello! How AreYou? you Hello! How ? are

20. Sequencing & Reassembling Hello! How are you ? Hello! 1/5 How 2/5 Are 3/5 You 4/5 ? 5/5 Hello! How are you ? AB Hello! 1/5 How 2/5 Are 3/5 You 4/5 ? 5/5 Hello! 1/5 How 2/5 Are 3/5 You 4/5 ? 5/5 Hello! How are you ?

21. Error Correction Hello! How are you ? Hello! 1/5 How 2/5 Are 3/5 You 4/5 ? 5/5 Hello! How are you ? Hello! 1/5 Are 3/5 You 4/5 ? 5/5 Hello! 1/5 Are 3/5 You 4/5 ? 5/5 Segment Missing Hello! 1/5 Are 3/5 You 4/5 ? 5/5 How 2/5 How 2/5 Hello! How are you ? Hello! How are you ? AB

22. Flow Control - Windowing Sending 3-window Received 3-window Ack-Rec- 3 Sending 5-window Received 4-window AB Ack. Received- 4 PC-A can send 4 Segment at a time to PC-B PC-A can send 4 Segment at a time to PC-B

23. How data flows from Transport Layer Data TH Segment Application Presentation Session Transport Network Data Link Physical

24. Network Layer Network Layer is responsible for providing best path to data to reach destination. Logical Addressing sits on this layer. Device working on Network Layer is Router. It is divided into two parts Routed Protocols e.g. IP, IPX, Apple Talk. Routing Protocols e.g. RIP, IGRP, OSPF, EIGRP Application Presentation Session Transport Network Data Link Physical Network

25. Routed Protocols Hello! How are you ? 192.168.1.1192.168.1.2 AB Segment Source IP 192.168.1.1 Destination IP 192.168.1.2 Source IP 192.168.1.1 Destination IP 192.168.1.2 Segment Hello! How are you ?

26. Routing Protocols A www.zoomgroup.com

27. How data flows from Network Layer Data Segment NH e.g. Router Packet Application Presentation Session Transport Network Data Link Physical

28. Data link Layer Datalink Layer is divided into two Sub Layers : LLC – Logical Link Control It talks about Wan protocols e.g. PPP, HDLC, Frame-relay MAC – Media Access Control It talks about Physical Address. It is 48 bit Addressing i.e. 12 digit Hexadecimal No. It is also responsible for Error Detection Device working on Data Link Layer is Switch, Bridge, NIC. Application Presentation Session Transport Network Data Link Physical Data Link

29. Error Detection – CRC Check Hello! How are you ? Packet Source MAC 00-20-18-C0-07-71 Destination MAC 00-20-18-C0-07-72 000003243422222896965543499323434349943446323111143333300000324342222289696554349932343434994344632311114Error Detected 192.168.1.1 00-20-18-C0-07-71 192.168.1.2 00-20-18-C0-07-72 AB PC-A CRC No. 33333 PC-B CRC No. 11114 Error Detected For Error Correction Contact Source Transport layer PC-A CRC No. 33333 PC-B CRC No. 11114 Error Detected For Error Correction Contact Source Transport layer

30. Error Detection – CRC Check Packet Source MAC 00-20-18-C0-07-71 Destination MAC 00-20-18-C0-07-72 00000324342222289696554349932343434994344632311114202020000032434222228969655434993234343499434463231111420202 Source MAC 00-20-18-C0-07-71 Destination MAC 00-20-18-C0-07-72 Packet Hello! How are you ? 192.168.1.1 00-20-18-C0-07-71 192.168.1.2 00-20-18-C0-07-72 AB

31. e.g. Switch How data flows from Data Link Layer Data Segment DH Packet DT Application Presentation Session Transport Network Data Link Physical Packet Frame

32. Physical Layer Physical Layer is responsible for electrical, mechanical or procedural checks. Data will be converted in Binary that is 0’s & 1’s. Data will be in the form of electrical pulses if it is Coaxial or Twisted Pair cable and in the form of Light if it is Fiber Optic Cable. Devices working at Physical Layer are Hubs, Repeaters, Cables, Modems etc. Application Presentation Session Transport Network Data Link Physical

33. Physical Layer Example Frame 1010101010101010 Frame Hello! How are you ? AB 01010110101010101010101011010101101010101010101010010101101010101010101010110101011010101010101010100101011010101010101010101

34. How data flows from Physical Layer Data Segment Packet Frame Bits e.g. Hub Application Presentation Session Transport Network Data Link Physical

35. Segment Packet Frame A B Packet Data Bits Data Segment Data Encapsulation & De-capsulation Packet Data Application Presentation Session Transport Network Data Link Physical Application Presentation Session Transport Network Data Link Physical Bits DHDTNH TH Segment Packet DT Packet DHDTDH NH Segment NHTH Data TH Frame Packet

36. Application Transport Internet Network Access Network Access Comparing OSI with TCP/IP Layers OSI LayersTCP/IP Layers Application Presentation Session Transport Network Data Link Physical