Chapter 2 Network Models Http netwk hannam ac

Chapter 2 네트워크 모델 (Network Models) Http: //netwk. hannam. ac. kr HANNAM UNIVERSITY 11

2장 네트워크 모델 2. 1 계층화된 임무 (Layered Tasks) 2. 2 OSI 모델 (Model) 2. 3 OSI 모델의 계층 (Layers) 2. 4 TCP/IP 프로토콜 그룹 (Suite) 2. 5 주소 지정 (Addressing) 2. 6 요약 (Summary) Http: //netwk. hannam. ac. kr HANNAM UNIVERSITY 22

2. 1 계층화된 임무 q 편지를 보내는 과정 Http: //netwk. hannam. ac. kr HANNAM UNIVERSITY 33

2. 2 OSI 모델 Http: //netwk. hannam. ac. kr HANNAM UNIVERSITY 77

대등 대 대등 프로세스(peer-to-peer process) Http: //netwk. hannam. ac. kr HANNAM UNIVERSITY 99

인터넷 모델을 이용한 변환 Http: //netwk. hannam. ac. kr HANNAM UNIVERSITY 10 10

2. 3 OSI 모델의 계층 q 물리 층(Physical Layer) q 데이터 링크 층(Data Link Layer) q 네트워크 층(Network Layer) q 전송 층(Transport Layer) q 세션 층(Session Layer) q 표현 층(Presentation Layer) q 응용 층(Application Layer) Http: //netwk. hannam. ac. kr HANNAM UNIVERSITY 11 11

물리층(계속) q 물리 층 Http: //netwk. hannam. ac. kr HANNAM UNIVERSITY 13 13

물리층(physical layer) 물리층은 개별 비트들을 한 노드에서 음 노드로 전달하는 책임을 갖는다. 다 The physical layer is responsible for movements of individual bits from one hop (node) to the next. Http: //netwk. hannam. ac. kr HANNAM UNIVERSITY 16 16

데이터 링크층(data link layer) Http: //netwk. hannam. ac. kr HANNAM UNIVERSITY 18 18

데이터 링크층(data link layer) 데이터링크층은 한 노드에서 다른 노드로 프레임을 전송하는 책임을 갖는다. The data link layer is responsible for moving frames from one hop (node) to the next. Http: //netwk. hannam. ac. kr HANNAM UNIVERSITY 19 19

홉-대-홉(hop-to-hop, node-to-node) 전달 Http: //netwk. hannam. ac. kr HANNAM UNIVERSITY 20 20

예1 Http: //netwk. hannam. ac. kr HANNAM UNIVERSITY 21 21

네트워크층(network layer) Http: //netwk. hannam. ac. kr HANNAM UNIVERSITY 23 23

네트워크층(network layer) 네트워크 계층은 발신지 호스트로부터 최종 목적지 호 스트로 패킷을 전달하는 책임을 갖는다. The network layer is responsible for the delivery of individual packets from the source host to the destination host. Http: //netwk. hannam. ac. kr HANNAM UNIVERSITY 24 24

발신지 대 목적지 전달 Http: //netwk. hannam. ac. kr HANNAM UNIVERSITY 25 25

예2 Http: //netwk. hannam. ac. kr HANNAM UNIVERSITY 26 26

전송층(transport layer) Http: //netwk. hannam. ac. kr HANNAM UNIVERSITY 28 28

전송층(transport layer) 전송층은 하나의 프로세스로부터 다른 프로세스로 메 시지를 전달하는 책임을 진다. The transport layer is responsible for the delivery of a message from one process to another. Http: //netwk. hannam. ac. kr HANNAM UNIVERSITY 29 29

전송층(transport layer) q 메시지의 프로세스 대 프로세스 전달 Http: //netwk. hannam. ac. kr HANNAM UNIVERSITY 30 30

전송층(transport layer) q 예3 Http: //netwk. hannam. ac. kr HANNAM UNIVERSITY 31 31

세션층(Session Layer) q 네트워크 대화 제어자 Http: //netwk. hannam. ac. kr HANNAM UNIVERSITY 32 32

세션층(계속) q 기능 ■ 세션 관리(Session management) ■ 동기화(Synchronization) ■ 대화 제어(Dialog control) ■ 원활한 종료(Graceful Close) 세션층은 대화 제어와 동기화에 책임을 갖는다. The session layer is responsible for dialog control and synchronization. Http: //netwk. hannam. ac. kr HANNAM UNIVERSITY 33 33

표현층(계속) q Presentation Layer Http: //netwk. hannam. ac. kr HANNAM UNIVERSITY 35 35

표현층(계속) q 기능 ■ 변환(Translation) ■ 암호화(Encryption) ■ 압축(Compression) ■ 보안(Security) 표현층은 변환, 압축, 암호화에 책임을 갖는다 The presentation layer is responsible for translation, compression, and encryption. Http: //netwk. hannam. ac. kr HANNAM UNIVERSITY 36 36

응용층(application layer) Http: //netwk. hannam. ac. kr HANNAM UNIVERSITY 37 37

응용층(application layer) 응용 층은 사용자에게 서비스를 제공하는 책임을 진다. The application layer is responsible for providing services to the user. Http: //netwk. hannam. ac. kr HANNAM UNIVERSITY 39 39

각 계층의 기능 요약 Http: //netwk. hannam. ac. kr HANNAM UNIVERSITY 40 40

2 -4 TCP/IP 프로토콜 그룹 (SUITE) TCP/IP 프로토콜 그룹(protocol suite)의 계층구조는 OSI 모 델과 정확하게 일치하지 않는다. 원래의 TCP/IP 프로토콜 그룹은host-to-network, internet, transport, 그리고 application 라는 4개의 계층구조를 갖는 것으로 규정되었다. 그렇지만, TCP/IP를 OSI와 비 교 할 때 , TCP/IP 프 로 토 콜 그 룹 은 physical, data link, network, transport, 그 리 고 application라 는 5개의 계층으로 되어 있다고 말할 수 있다. Topics discussed in this section: Physical and Data Link Layers Network Layer Transport Layer Application Layer Http: //netwk. hannam. ac. kr HANNAM UNIVERSITY 41 41

TCP/IP and OSI model Http: //netwk. hannam. ac. kr HANNAM UNIVERSITY 42 42

2 -5 주소지정(ADDRESSING) Physical, logical, port, 그리고 specific 라는 4개의 주소 레 벨이 TCP/IP 프로토콜을 사용하는 인터넷에서 사용된다. Topics discussed in this section: Physical Addresses Logical Addresses Port Addresses Specific Addresses Http: //netwk. hannam. ac. kr HANNAM UNIVERSITY 43 43

TCP/IP 주소 지정 Http: //netwk. hannam. ac. kr HANNAM UNIVERSITY 44 44

TCP/IP 계층과 주소의 관계 Http: //netwk. hannam. ac. kr HANNAM UNIVERSITY 45 45

Figure 2. 19 Physical addresses Http: //netwk. hannam. ac. kr HANNAM UNIVERSITY 47 47

Example 2. 2 As we will see in Chapter 13, most local-area networks use a 48 -bit (6 -byte) physical address written as 12 hexadecimal digits; every byte (2 hexadecimal digits) is separated by a colon, as shown below: 07: 01: 02: 01: 2 C: 4 B A 6 -byte (12 hexadecimal digits) physical address. Http: //netwk. hannam. ac. kr HANNAM UNIVERSITY 48 48

Example 2. 3 Figure 2. 20 shows a part of an internet with two routers connecting three LANs. Each device (computer or router) has a pair of addresses (logical and physical) for each connection. In this case, each computer is connected to only one link and therefore has only one pair of addresses. Each router, however, is connected to three networks (only two are shown in the figure). So each router has three pairs of addresses, one for each connection. Http: //netwk. hannam. ac. kr HANNAM UNIVERSITY 49 49

IP 주소 (IP Address) Http: //netwk. hannam. ac. kr HANNAM UNIVERSITY 50 50

Example 2. 4 Figure 2. 21 shows two computers communicating via the Internet. The sending computer is running three processes at this time with port addresses a, b, and c. The receiving computer is running two processes at this time with port addresses j and k. Process a in the sending computer needs to communicate with process j in the receiving computer. Note that although physical addresses change from hop to hop, logical and port addresses remain the same from the source to destination. Http: //netwk. hannam. ac. kr HANNAM UNIVERSITY 51 51

포트 주소(Port address) Http: //netwk. hannam. ac. kr HANNAM UNIVERSITY 52 52

The physical addresses will change from hop to hop, but the logical addresses usually remain the same. Http: //netwk. hannam. ac. kr HANNAM UNIVERSITY 53 53

Example 2. 5 As we will see in Chapter 23, a port address is a 16 -bit address represented by one decimal number as shown. 753 A 16 -bit port address represented as one single number. Http: //netwk. hannam. ac. kr HANNAM UNIVERSITY 54 54

2. 6 요 약 Http: //netwk. hannam. ac. kr HANNAM UNIVERSITY 55 55