Chapter 2. The OSI Model and TCP/IP Protocol Suite. PDF created with FinePrint pdffactory Pro trial version

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1 Chapter 2 The OSI Mdel and TCP/IP Prtcl Suite PDF created with FinePrint pdffactry Pr trial versin

2 Outline THE OSI MODEL LAYERS IN THE OSI MODEL TCP/IP PROTOCOL SUITE ADDRESSING TCP/IP VERSIONS PDF created with FinePrint pdffactry Pr trial versin

3 2.1 THE OSI MODEL The McGraw-Hill Cmpanies, Inc., 2000 PDF created with FinePrint pdffactry Pr trial versin

4 Figure 2-1 OSI Mdel The McGraw-Hill Cmpanies, Inc., 2000 PDF created with FinePrint pdffactry Pr trial versin

5 Layered Architecture Within a single machine Each layer calls upn the services f the layer just belw it Fr example, layer 3 uses the services prvided by layer 2 and prvides services fr layer 4 PDF created with FinePrint pdffactry Pr trial versin

6 Layered Architecture (Cnt.) Between machines Layer x n ne machine cmmunicates with layer x n anther machine This cmmunicatin is gverned by a series f rules and cnventins called prtcls PDF created with FinePrint pdffactry Pr trial versin

7 Layered Architecture (Cnt.) As the message travels frm A t B, it may pass thrugh intermediate ndes These intermediate ndes usually invlve nly the first three layers f the OSI mdel As shwn in the next slide PDF created with FinePrint pdffactry Pr trial versin

8 Figure 2-2 OSI Layers The McGraw-Hill Cmpanies, Inc., 2000 PDF created with FinePrint pdffactry Pr trial versin

9 Peer-t-Peer Prcesses The prcesses n each machine that cmmunicate at a given layer are called peer-t-peer prcesses Each layer in the sending device added its wn infrmatin t the message it receives frm the layer just abve it At the receiving machine, the message is unwrapped layer by layer PDF created with FinePrint pdffactry Pr trial versin

10 Headers are added t the data at layers 6, 5, 4, 3, and 2. Trailers are usually added nly at layer 2. PDF created with FinePrint pdffactry Pr trial versin The McGraw-Hill Cmpanies, Inc., 2000

11 Figure 2-3 An Exchange Using the OSI Mdel PDF created with FinePrint pdffactry Pr trial versin The McGraw-Hill Cmpanies, Inc., 2000

12 2.2 LAYERS IN THE OSI MODEL The McGraw-Hill Cmpanies, Inc., 2000 PDF created with FinePrint pdffactry Pr trial versin

13 Figure 2-4 Physical Layer The McGraw-Hill Cmpanies, Inc., 2000 PDF created with FinePrint pdffactry Pr trial versin

14 Physical Layer Physical characteristics f interface and media Interface between the devices and transmissin media The type f transmissin media Representatin f bits Define the type f encding (hw 0s and 1s are changed t signals) PDF created with FinePrint pdffactry Pr trial versin

15 Physical Layer (Cnt.) Data rate The number f bits sent each secnd Synchrnizatin f bits The sender and receiver must nt nly use the same bit rate but must als be synchrnized at the bit level PDF created with FinePrint pdffactry Pr trial versin

16 Physical Layer (Cnt.) Line cnfiguratin Be cncerned with the cnnectin f devices t the media Pint-t-pint cnfiguratin Tw devices are cnnected thrugh a dedicated link Multipint cnfiguratin A link is shared between several devices Physical tplgy Define hw devices are cnnected t make a netwrk Fr example, mesh, star, ring, r bus tplgy PDF created with FinePrint pdffactry Pr trial versin

17 Physical Layer (Cnt.) Transmissin mde Define the directin f transmissin between tw devices Simple mde nly ne device can send Half-duplex mde tw devices can send and receive but nt at the same time Full-duplex mde Tw devices can send and receive at the same time PDF created with FinePrint pdffactry Pr trial versin

18 Data Link Layer Transfrm the physical layer t a reliable link Make the physical layer appear errr free t the upper layer PDF created with FinePrint pdffactry Pr trial versin

19 Figure 2-5 Data Link Layer The McGraw-Hill Cmpanies, Inc., 2000 PDF created with FinePrint pdffactry Pr trial versin

20 Data Link Layer Framing Divide the stream f bits int frames Physical addressing nly ne hp Flw cntrl Errr cntrl Detect and retransmit damaged r lst frames Prevent duplicatin f frames PDF created with FinePrint pdffactry Pr trial versin

21 Data Link Layer (Cnt.) Access cntrl Determine which device has cntrl ver the link at any given time PDF created with FinePrint pdffactry Pr trial versin

22 Figure 2-6 Nde-t-Nde (Hp-t-Hp) Delivery PDF created with FinePrint pdffactry Pr trial versin The McGraw-Hill Cmpanies, Inc., 2000

23 Netwrk Layer Be respnsible fr the surce-t-destinatin delivery f a packet pssibly acrss multiple netwrks (links) Data link layer take care f the delivery f the packet between tw systems n the same netwrk (links) Netwrk layer ensures the delivery f a packet frm its pint f rigin t it final destinatin PDF created with FinePrint pdffactry Pr trial versin

24 Figure 2-7 Netwrk Layer The McGraw-Hill Cmpanies, Inc., 2000 PDF created with FinePrint pdffactry Pr trial versin

25 Netwrk Layer Lgical addressing Physical addressing in the data link layer handles the addressing prblem lcally If a packet pass the netwrk bundary Ruting We need anther addressing system t distinguish the surce and destinatin systems PDF created with FinePrint pdffactry Pr trial versin

26 Figure 2-8 End-t-End Delivery by the Netwrk Layer PDF created with FinePrint pdffactry Pr trial versin The McGraw-Hill Cmpanies, Inc., 2000

27 Transprt Layer Be respnsible fr surce-t-destinatin (endt-end) delivery f the entire message Netwrk layer nly versees the end-t-end delivery f individual packets Oversee bth errr cntrl and flw cntrl at the surce-t-destinatin level PDF created with FinePrint pdffactry Pr trial versin

28 Figure 2-9 Transprt Layer The McGraw-Hill Cmpanies, Inc., 2000 PDF created with FinePrint pdffactry Pr trial versin

29 Transprt Layer Service-pint addressing Service-pint address: prt address The netwrk layer gets each packet t the crrect cmputer The transprt layer gets the entire message t the crrect prcess n that cmputer Segmentatin and reassembly PDF created with FinePrint pdffactry Pr trial versin

30 Transprt Layer (Cnt.) Cnnectin cntrl Cnnectinless Cnnectin-riented Flw cntrl End t end flw cntrl The flw cntrl, hwever, at the data link layer is acrss a single link PDF created with FinePrint pdffactry Pr trial versin

31 Transprt Layer (Cnt.) Errr cntrl End t end errr cntrl that makes sure that the entire message arrives withut errr (damage, lss, r duplicatin) Errr crrectin is usually achieved thrugh retransmissin The errr cntrl, hwever, at the data link layer is acrss a single link and applies t a single frame PDF created with FinePrint pdffactry Pr trial versin

32 Figure 2-10 Reliable End-t-End Delivery f a Message end-t-end delivery by the transprt layer PDF created with FinePrint pdffactry Pr trial versin The McGraw-Hill Cmpanies, Inc., 2000

33 Sessin Layer Sessin layer is the netwrk dialg cntrller It establishes, maintains, and synchrnizes the interactin between cmmunicatin systems PDF created with FinePrint pdffactry Pr trial versin

34 Figure 2-11 Sessin Layer The McGraw-Hill Cmpanies, Inc., 2000 PDF created with FinePrint pdffactry Pr trial versin

35 Sessin Layer Dialg cntrl Allw tw systems t enter a dialg Allw the cmmunicatin between tw prcesses in Half-duplex Full-duplex Synchrnizatin Allw a prcess t add checkpints (synchrnizatin pints) int a stream f data PDF created with FinePrint pdffactry Pr trial versin

36 Presentatin Layer Be cncerned with the syntax and semantics f the infrmatin exchanged between tw systems PDF created with FinePrint pdffactry Pr trial versin

37 Figure 2-12 Presentatin Layer The McGraw-Hill Cmpanies, Inc., 2000 PDF created with FinePrint pdffactry Pr trial versin

38 Presentatin Layer Translatin Different cmputers use different encding systems The presentatin layer is respnsible fr interperability between these different encding methds Encryptin Cmpressin PDF created with FinePrint pdffactry Pr trial versin

39 Applicatin Layer The applicatin layer enables the user, whether human r sftware, t access the netwrk PDF created with FinePrint pdffactry Pr trial versin

40 Figure 2-13 Applicatin Layer The McGraw-Hill Cmpanies, Inc., 2000 PDF created with FinePrint pdffactry Pr trial versin

41 Applicatin Layer Specific services prvided by the applicatin layer Netwrk virtual terminal File transfer, access, and management (FTAM) Mail services Directry services PDF created with FinePrint pdffactry Pr trial versin

42 Figure 2-14 Summary f Layers PDF created with FinePrint pdffactry Pr trial versin The McGraw-Hill Cmpanies, Inc., 2000

43 2.3 TCP/IP PROTOCOL SUITE PDF created with FinePrint pdffactry Pr trial versin

44 TCP/IP Prtcl Suite TCP/IP prtcl suite was develped prir t the OSI mdel and is made f five layers Physical, data link, netwrk, transprt, and applicatin layers The first fur layers crrespnd t the first fur layer f the OSI mdel PDF created with FinePrint pdffactry Pr trial versin

45 TCP/IP Prtcl Suite The three tpmst layers is OSI mdel are represented in TCP by a single layer called the applicatin layer PDF created with FinePrint pdffactry Pr trial versin

46 Figure 2-15 TCP/IP and OSI Mdel PDF created with FinePrint pdffactry Pr trial versin The McGraw-Hill Cmpanies, Inc., 2000

47 Physical and Data Link Layers TCP/IP des nt define any specific prtcl TCP/IP supprts all f the standard and prprietary prtcls PDF created with FinePrint pdffactry Pr trial versin

48 Netwrk Layer Internetwrking Prtcls (IP) Fur supprting prtcls ARP RARP ICMP IGMP PDF created with FinePrint pdffactry Pr trial versin

49 Internetwrking Prtcl (IP) The packets in IP are called datagrams Unreliable and cnnectinless datagram prtcl Best-effrt delivery services Prvide n errr checking r tracking PDF created with FinePrint pdffactry Pr trial versin

50 Address Reslutin Prtcl (ARP) Assciate an IP address with the physical address Data in LAN are transmitted by the physical address PDF created with FinePrint pdffactry Pr trial versin

51 Reverse Address Reslutin Prtcl (RARP) Discver a hst s internet address via its physical address Used when A cmputer is first cnnected t the netwrk When a diskless cmputer is bted PDF created with FinePrint pdffactry Pr trial versin

52 Internet Cntrl Message Prtcl (ICMP) A mechanism used t send ntificatin f datagram prblems back t the sender ICMP sends query and errr reprting messages PDF created with FinePrint pdffactry Pr trial versin

53 Internet Grup Message Prtcl (IGMP) Facilitate the simultaneus transmissin f a message t a grup f recipients PDF created with FinePrint pdffactry Pr trial versin

54 Transprt Layer TCP/UDP A prcess-t-prcess prtcl IP A hst-t-hst prtcl PDF created with FinePrint pdffactry Pr trial versin

55 User Datagram Prtcl (UDP) Add nly Prt numbers Checksum errr cntrl length PDF created with FinePrint pdffactry Pr trial versin

56 Transmissin Cntrl Prtcl (TCP) Reliable cnnectin-riented prtcl PDF created with FinePrint pdffactry Pr trial versin

57 2.4 ADDRESSING PDF created with FinePrint pdffactry Pr trial versin The McGraw-Hill Cmpanies, Inc., 2000

58 Figure 2-16 Addresses in TCP/IP The McGraw-Hill Cmpanies, Inc., 2000 PDF created with FinePrint pdffactry Pr trial versin

59 Figure 2-17 RelatinshipfLayers andaddressesin TCP/IP PDF created with FinePrint pdffactry Pr trial versin The McGraw-Hill Cmpanies, Inc., 2000

60 Physical Address Als called link address, the address f a nde as defined by its LAN r WAN Ethernet: 6 byte LcalTalk: 1 byte Physical address can be either Unicast address Multicast address Bradcast address PDF created with FinePrint pdffactry Pr trial versin

61 Example 1 Figure 2.18 shws an example f physical addresses. PDF created with FinePrint pdffactry Pr trial versin The McGraw-Hill Cmpanies, Inc., 2000

62 Figure 2-18 Physical Addresses PDF created with FinePrint pdffactry Pr trial versin The McGraw-Hill Cmpanies, Inc., 2000

63 Example 2 Mst lcal area netwrks use a 48-bit (6 bytes) physical address written as 12 hexadecimal digits, with every 2 bytes separated by a hyphen as shwn belw: C-4B A 6-byte (12 hexadecimal digits) physical address PDF created with FinePrint pdffactry Pr trial versin The McGraw-Hill Cmpanies, Inc., 2000

64 Internet Address Prvide universal cmmunicatin services that are independent f underlying physical netwrk Different netwrks can have different address frmat A universal addressing system is thus needed Internet address can als be either in unicast, multicast and bradcast 4 bytes lng in IPv4 PDF created with FinePrint pdffactry Pr trial versin

65 Example 3 Next slide shws an example f Internet addresses. Netwrk address A and physical address 10 => send data t => Netwrk address P and physical address 95 IP address des nt change alng the trip Hwever, physical address changes frm netwrk t netwrk PDF created with FinePrint pdffactry Pr trial versin The McGraw-Hill Cmpanies, Inc., 2000

66 Figure 2-19 IP Addresses The McGraw-Hill Cmpanies, Inc., 2000 PDF created with FinePrint pdffactry Pr trial versin

67 Example 4 As we will see in Chapter 4, an Internet address (in IPv4) is 32 bits in length, nrmally written as fur decimal numbers, with each number representing 1 byte. The numbers are separated by a dt. Belw is an example f such an address PDF created with FinePrint pdffactry Pr trial versin The McGraw-Hill Cmpanies, Inc., 2000

68 Prt Address A label assigns t a prcess 16 bits lng PDF created with FinePrint pdffactry Pr trial versin

69 Example 5 Next slide shws an example f transprt layer cmmunicatin. Prcess with prt address j send data t anther prcess with prt address k The McGraw-Hill Cmpanies, Inc., 2000 PDF created with FinePrint pdffactry Pr trial versin

70 Figure 2-20 Prt Addresses The McGraw-Hill Cmpanies, Inc., 2000 PDF created with FinePrint pdffactry Pr trial versin

71 Example 6 As we will see in Chapters 11 and 12, a prt address is a 16-bit address represented by ne decimal number as shwn belw. 753 A 16-bit prt address PDF created with FinePrint pdffactry Pr trial versin The McGraw-Hill Cmpanies, Inc., 2000

72 2.5 TCP/IP VERSIONS The McGraw-Hill Cmpanies, Inc., 2000 PDF created with FinePrint pdffactry Pr trial versin

73 Versin Versin 4 What we current used Versin 5 Only a prpsal Based n the OSI mdel Versin 6 Als called IPng (IP next generatin) PDF created with FinePrint pdffactry Pr trial versin