1. The OSI Model and the TCP/IP Protocol Suite
Chapter 2
The OSI Model and the TCP/IP Protocol Suite
Objectives
Upon completion you will be able to:
Understand the architecture of the OSI model
Understand the layers of the OSI model and their functions
Understand the architecture of the TCP/IP Protocol Suite
Differentiate between the OSI model and the TCP/IP Suite
Differentiate between the three types of Internet addresses

2. CONTENTS THE OSI MODEL LAYERS IN THE OSI MODEL TCP/IP PROTOCOL SUITE
ADDRESSING
TCP/IP VERSIONS

3. 2.1 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.
The topics discussed in this section include:
Layered Architecture
Peer-to-Peer Processes
Encapsulation

4. 2.1 OSI 모델 Open System Interconnection
ISO 7498 OSI Basic Reference Model
모든 종류의 컴퓨터 시스템간 통신을 가능하게 하는 네트워크 설계를 위한 계층 구조
서로 연관된 7 계층으로 구성

5. ISO is the organization. OSI is the model
Note:
ISO is the organization. OSI is the model

6. 2.1 OSI 모델(계속)
OSI 모델

7. 2.1 OSI 모델(계속)
OSI 계층 구조

8. Headers are added to the data at layers 6, 5, 4, 3, and 2
Headers are added to the data at layers 6, 5, 4, 3, and Trailers are usually added only at layer 2.

9. 2.1 OSI 모델(계속)
OSI 모델을 이용한 교환

10. 2.2 Layers in the OSI Model
The functions of each layer in the OSI model is briefly described.
The topics discussed in this section include:
Physical Layer
Data Link Layer
Network Layer
Transport Layer
Session Layer
Presentation Layer
Application Layer
Summary of Layers

11. 2.2 OSI 모델의 계층 물리계층(physical layer)
물리적인 매체를 통하여 비트 스트림을 전송하는데 필요한 기능 제공

12. Note:
The physical layer is responsible for the movement of individual bits from one hop (node) to the next.

13. 2.2 OSI 모델의 계층(계속) 물리계층의 주요 기능 장치와 전송 매체간의 인터페이스 특성과 전송 매체 유형 규정
비트 표현 방법(부호화 유형)
데이터 전송 속도(bps)
비트의 동기화(송수신자간 클록)
회선 구성(점대점, 다중점)
접속형태(mesh, star, ring, bus, tree)
전송 모드(simplex, half-duplex, full-duplex)

14. 2.2 OSI 모델의 계층(계속)
데이터링크계층(data link layer)

15. 2.2 OSI 모델의 계층(계속) 데이터링크층의 주요 기능 프레임(frame) 구성 물리 주소 지정(송수신자 주소) 흐름 제어
오류 제어
접근 제어

16. Note:
The data link layer is responsible for moving frames from one hop (node) to the next.

17. 2.2 OSI 모델의 계층(계속)
노드-대-노드 전달

18. 2.2 OSI 모델의 계층(계속) 네트워크계층(network layer)
패킷(packet)을 네트워크를 통하여 발신지에서 목적지까지 전달 책임

19. Note:
The network layer is responsible for the delivery of individual packets from the source host to the destination host.

20. 2.2 OSI 모델의 계층(계속) 네트워크계층 주요 기능 논리 주소 지정 라우팅
패킷이 최종 목적지에 전달될 수 있도록 경로를 지정하거나 교환 기능 제공

21. 2.2 OSI 모델의 계층(계속)
종단-대-종단 전송

22. 2.2 OSI 모델의 계층(계속) 전송계층(transport layer)
발신지에서 목적지(종단-대-종단)까지 전체 메시지 전달기능 제공

23. Note:
The transport layer is responsible for the delivery of a message from one process to another.

24. 2.2 OSI 모델의 계층(계속) 전송계층 주요 기능 서비스 지점 주소지정(포트 주소)
분할과 재조립(Segmentation and reassembly)
연결 제어(Connection Control)
흐름 제어(Flow Control)
오류 제어(Error Control)

25. 2.2 OSI 모델의 계층(계속)
신뢰성 있는 종단-대-종단 메시지 전송

26. 2.2 OSI 모델의 계층(계속) 세션계층(session layer)
통신 시스템간의 상호 대화 설정, 유지, 동기화 기능 제공

27. 2.2 OSI 모델의 계층(계속)
세션계층의 주요 기능
대화 제어(반이중, 전이중)
동기화(검사점 추가)

28. 2.2 OSI 모델의 계층(계속)
표현계층(presentation layer)

29. 2.2 OSI 모델의 계층(계속) 표현계층의 주요 기능 변환(Translation) 암호화(Encryption)
압축(Compression)

30. 2.2 OSI 모델의 계층(계속) 응용계층(application layer)
사용자나 소프트웨어를 네트워크에 접근 가능하도록 하는 기능 제공

31. 2.2 OSI 모델의 계층(계속) 응용계층 주요 기능 네트워크 가상 터미널(Network Virtual Terminal)
파일 접근, 전송 및 관리(File Transfer, Access, and Management)
우편 서비스(Mail Service)
디렉토리 서비스(Directory Service)

32. 2.2 OSI 모델의 계층(계속)
계층별 요약

33. 2.3 TCP/IP Protocol Suite
The TCP/IP protocol suite is made of five layers: physical, data link, network, transport, and application. The first four layers provide physical standards, network interface, internetworking, and transport functions that correspond to the first four layers of the OSI model. The three topmost layers in the OSI model, however, are represented in TCP/IP by a single layer called the application layer.
The topics discussed in this section include:
Physical and Data Link Layers
Network Layer
Transport Layer
Application Layer

34. 2.3 TCP/IP 프로토콜
TCP/IP와 OSI 모델

35. 2.3 TCP/IP 프로토콜(계속) TCP/IP 프로토콜 물리계층과 데이터링크계층 네트워크 계층
기존의 모든 표준과 기술적인 프로토콜 지원
네트워크 계층
인터넷 프로토콜(IP) : host-to-host protocol
주소변환 프로토콜(ARP)
역주소변환 프로토콜(RARP)
인터넷 제어 메시지 프로토콜(ICMP)
인터넷 그룹 메시지 프로토콜(IGMP)

36. 2.3 TCP/IP 프로토콜(계속) 전송계층 응용계층 사용자 데이터그램 프로토콜(UDP) 전송 제어 프로토콜(TCP)
OSI 모델의 세션, 표현, 응용층을 합친것

37. 2.4 Addressing
Three different levels of addresses are used in an internet using the TCP/IP protocols: physical (link) address, logical (IP) address, and port address.
The topics discussed in this section include:
Physical Address
Logical Address
Port Address

38. 2.4 주소지정
TCP/IP에서 사용하는 주소

39. 2.4 주소지정(계속)
TCP/IP에서 주소와 계층간의 관계

40. 2.4 주소지정(계속) 물리 주소 링크 주소 WAN이나 LAN에서 정의된 노드의 주소
이더넷 네트워크 인터페이스 카드(NIC) 6바이트(48비트) 주소
유니캐스트(unicast), 멀티캐스트(multicast), 브로드캐스트(broadcast)

41. Example 1
In Slide 42 a node with physical address 10 sends a frame to a node with physical address 87. The two nodes are connected by a link. At the data link level this frame contains physical (link) addresses in the header. These are the only addresses needed. The rest of the header contains other information needed at this level. The trailer usually contains extra bits needed for error detection.

42. 2.4 주소지정(계속)
물리 주소

43. A 6-byte (12 hexadecimal digits) physical address.
Example 2
As we will see in Chapter 3, most local area networks use a 48-bit (6 bytes) physical address written as 12 hexadecimal digits, with every 2 bytes separated by a colon as shown below:
07:01:02:01:2C:4B
A 6-byte (12 hexadecimal digits) physical address.

44. 2.4 주소지정(계속) 인터넷 주소 현재 인터넷에 연결된 호스트 식별 : 32비트 주소 체계
유니캐스트(단일사용자), 멀티캐스트(그룹수신자), 브로드캐스트(네트워크 내의 모든 시스템)

45. Example 3
In Slide 47 we want to send data from a node with network address A and physical address 10, located on one LAN, to a node with a network address P and physical address 95, located on another LAN. Because the two devices are located on different networks, we cannot use link addresses only; the link addresses have only local jurisdiction. What we need here are universal addresses that can pass through the LAN boundaries. The network (logical) addresses have this characteristic.

46. Example 3 (Continued)
The packet at the network layer contains the logical addresses, which remain the same from the original source to the final destination (A and P, respectively, in the figure). They will not change when we go from network to network. However, the physical addresses will change as the packet moves from one network to another. The boxes labeled routers are internetworking devices, which we will discuss in Chapter 3.

47. 2.4 주소지정(계속)
IP 주소

48. 132.24.75.9 An internet address in IPv4 in decimal numbers
Example 4
As we will see in Chapter 4, an Internet address (in IPv4) is 32 bits in length, normally written as four decimal numbers, with each number representing 1 byte. The numbers are separated by a dot. Below is an example of such an address.
An internet address in IPv4 in decimal numbers

49. Example 5
Slide 51 shows an example of transport layer communication. Data coming from the upperlayers have port addresses j and k ( j is the address of the sending process, and k is the address of the receiving process). Since the data size is larger than the network layer can handle, the data are split into two packets, each packet retaining the service-point addresses ( j and k). Then in the network layer, network addresses (A and P) are added to each packet.

50. Example 5 (Continued)
The packets can travel on different paths and arrive at the destination either in order or out of order. The two packets are delivered to the destination transport layer, which is responsible for removing the network layer headers and combining the two pieces of data for delivery to the upper layers.

51. 2.4 주소지정(계속)
포트 주소

52. 753 A 16-bit port address represented as one single number.
Example 6
As we will see in Chapters 11, 12, and 13, a port address is a 16-bit address represented by one decimal number as shown below.
753 A 16-bit port address represented as one single number.

53. 2.5 IP Versions
IP became the official protocol for the Internet in As the Internet has evolved, so has IP. There have been six versions since its inception. We look at the latter three versions here.
The topics discussed in this section include:
Version 4
Version 5
Version 6

54. 알림
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