1. Free Powerpoint Templates Page 1 Internetworking Models

2. Free Powerpoint Templates Page 2 The Layered Approach A reference model is a conceptual blueprint of how communications should take place. It addresses all the processes required for effective communication and divides these processes into logical groupings called layers. When a communication system is designed in this manner, it’s known as layered architecture

3. Free Powerpoint Templates Page 3 Advantages of Reference Models Allows multiple-vendor development through standardization of network components Allows various types of network hardware and software to communicate Prevents changes in one layer from affecting other layers, so it does not hamper development

4. Free Powerpoint Templates Page 4 OSI is the Open System Interconnection reference model for computer communication in a networking environment. The concept of a 7 layer model was provided by the work of Charles Bachman, Honeywell Information Services. Various aspects of OSI design evolved from the ARPANET. Work on a layered model of network architecture was started in the late 1970s based on a proposal developed by the International Standards Organization (ISO). Because of rapid prolification of TCP/IP protocol suite in 1990’s, OSI lagged behind. OSI protocols are still in existence and are used around the world. The OSI Reference Model

5. Free Powerpoint Templates Page 5 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

6. Free Powerpoint Templates Page 6 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 Port 0---1023 Application Presentation Session Transport Network Data Link Physical Application

7. Free Powerpoint Templates Page 7 7 Example of HTTP request ClientWeb Server http://www.zoomgroup.com

8. Free Powerpoint Templates Page 8 8 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

9. Free Powerpoint Templates Page 9 9 Example of FTP request ClientFTP Server ftp://ftp.microsoft.com

10. Free Powerpoint Templates Page 10 10 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

11. Free Powerpoint Templates Page 11 Examples of Networking Services Service Port No. HTTP80 FTP21 SMTP 25 TELNET23 TFTP69

12. Free Powerpoint Templates Page 12 Application 218025675369 How data flows from Application Layer Data Presentation Session Transport Network Data Link Physical

13. Free Powerpoint Templates Page 13 Presentation Layer Presentation Layer is responsible for converting data into standard format. Examples : ASCII, EBCDIC, JPEG, MPEG,WAV, MP3 Following tasks are perform at Presentation layer : Encoding – Decoding Encryption – Decryption Compression – Decompression Application Presentation Session Transport Network Data Link Physical Presentation

14. Free Powerpoint Templates Page 14 How data flows from Presentation Layer Data Application Presentation Session Transport Network Data Link Physical

15. Free Powerpoint Templates Page 15 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

16. Free Powerpoint Templates Page 16 How data flows from Session Layer Data Application Presentation Session Transport Network Data Link Physical

17. Free Powerpoint Templates Page 17 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 Segmentation Sequencing & Reassembling Flow Control Error Correction Application Presentation Session Transport Network Data Link Physical Transport

18. Free Powerpoint Templates Page 18 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

19. Free Powerpoint Templates Page 19 Connection Oriented ( TCP )

20. Free Powerpoint Templates Page 20 Segmentation Hello! How are you ? Hello!HowAreYou? Hello! How are you ? AB

21. Free Powerpoint Templates Page 21 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

22. Free Powerpoint Templates Page 22 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 ?

23. Free Powerpoint Templates Page 23 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

24. Free Powerpoint Templates Page 24 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

25. Free Powerpoint Templates Page 25 How data flows from Transport Layer Data TH Segment Application Presentation Session Transport Network Data Link Physical

26. Free Powerpoint Templates Page 26 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

27. Free Powerpoint Templates Page 27 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 ?

28. Free Powerpoint Templates Page 28 Routing Protocols A www.zoomgroup.com

29. Free Powerpoint Templates Page 29 How data flows from Network Layer Data Segment NH e.g. Router Packet Application Presentation Session Transport Network Data Link Physical

30. Free Powerpoint Templates Page 30 Datalink 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

31. Free Powerpoint Templates Page 31 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

32. Free Powerpoint Templates Page 32 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

33. Free Powerpoint Templates Page 33 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

34. Free Powerpoint Templates Page 34 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

35. Free Powerpoint Templates Page 35 Physical Layer Example Frame 1010101010101010 Frame Hello! How are you ? AB 01010110101010101010101011010101101010101010101010010101101010101010101010110101011010101010101010100101011010101010101010101

36. Free Powerpoint Templates Page 36 How data flows from Physical Layer Data Segment Packet Frame Bits e.g. Hub Application Presentation Session Transport Network Data Link Physical

37. Free Powerpoint Templates Page 37 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

38. Free Powerpoint Templates Page 38 TCP/IP reference model TCP/IP also has a network model. TCP/IP was on the path of development when the OSI standard was published and there was interaction between the designers of OSI and TCP/IP standards. The TCP/IP model is not same as OSI model. OSI is a seven-layered standard, but TCP/IP is a four layered standard. The OSI model has been very influential in the growth and development of TCP/IP standard, and that is why much OSI terminology is applied to TCP/IP.

39. Free Powerpoint Templates Page 39 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

40. Free Powerpoint Templates Page 40 Layer 4. Application Layer The top most layer of four layer TCP/IP model. Application layer is present on the top of the Transport layer. Application layer defines TCP/IP application protocols and how host programs interface with transport layer services to use the network. Application layer includes all the higher-level protocols like DNS (Domain Naming System), HTTP (Hypertext Transfer Protocol), Telnet, FTP (File Transfer Protocol), TFTP (Trivial File Transfer Protocol), SNMP (Simple Network Management Protocol), SMTP (Simple Mail Transfer Protocol), DHCP (Dynamic Host Configuration Protocol), X Windows, RDP (Remote Desktop Protocol) etc.

41. Free Powerpoint Templates Page 41 Layer 3. Transport Layer Transport Layer is the third layer of the four layer TCP/IP model. The position of the Transport layer is between Application layer and Internet layer. The purpose of Transport layer is to permit devices on the source and destination hosts to carry on a conversation. Transport layer defines the level of service and status of the connection used when transporting data. The main protocols included at Transport layer are TCP (Transmission Control Protocol) and UDP (User Datagram Protocol).

42. Free Powerpoint Templates Page 42 Layer 2. Internet Layer Internet Layer is the second layer of the four layer TCP/IP model. The position of Internet layer is between Network Access Layer and Transport Layer. Internet layer pack data into data packets known as IP datagrams, which contain source and destination address (logical address or IP address) information that is used to forward the datagrams between hosts and across networks. The Internet layer is also responsible for routing of IP datagrams.

43. Free Powerpoint Templates Page 43 Layer 1. Network Access Layer Network Access Layer is the first layer of the four layer TCP/IP model. Network Access layer defines details of how data is physically sent through the network, including how bits are electrically or optically signaled by hardware devices that interface directly with a network medium, such as coaxial cable, optical fiber, or twisted pair copper wire.

44. Free Powerpoint Templates Page 44 Cisco 3-layer Hierarchical Model

45. Free Powerpoint Templates Page 45 Core layer Responsible for transporting large amounts of traffic reliably and quickly. Only purpose is to switch traffic as fast as possible (speed and latency are factors). Failure at the Core layer can affect every user, design for fault tolerance at this level. Design specifications Don't Do at this layer –Don't use access lists, packet filtering, or VLAN Routing. –Don't support workgroup access here. –Don't expand (i.e. more routers), upgrade devices instead (faster with more capacity). Do at this layer –Design for high reliability (FDDI, Fast Ethernet with redundant links, or ATM). –Design for speed and low latency. –Use routing protocols with low convergence times.

46. Free Powerpoint Templates Page 46 Distribution layer Also called workgroup layer, this is the communication point between the access and core layers. Primary functions include routing, filtering, WAN access, and determining how packets can access the Core layer if necessary. Determines fastest/best path and sends request to the Core layer. Core layer will then quickly transport the request to the correct service. Place to implement network policies. Distribution Layer Functions Access lists, packet filtering, queuing. Security and network policies such as address translation and fire-walling. Re-distribution between routing protocols including static routing. Routing between VLANs and other workgroup support functions. Departmental or workgroup access. Definition of broadcast and multicast domains. Any media transitions that need to occur.

47. Free Powerpoint Templates Page 47 Access layer Controls local end user access to internetwork resources. Also called desktop layer. The resources most users need will be available locally. Distribution layer handles traffic for remote services. Continued use of access lists and filters. Creation of separate collision domains (segmentation). Workgroup connectivity at Distribution layer. Technologies such as DDR and Ethernet switching are seen in the Access layer. Static routing is here

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