Transcript 슬라이드 제목 없음

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
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CONTENTS
• THE OSI MODEL
• LAYERS IN THE OSI MODEL
• TCP/IP PROTOCOL SUITE
• ADDRESSING
• TCP/IP VERSIONS
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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
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2.1 OSI 모델
 Open System Interconnection
 ISO 7498 OSI Basic Reference Model
 모든 종류의 컴퓨터 시스템간 통신을 가능하게 하
는 네트워크 설계를 위한 계층 구조
 서로 연관된 7 계층으로 구성
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Note:
ISO is the organization.
OSI is the model
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2.1 OSI 모델(계속)
OSI 모델
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2.1 OSI 모델(계속)
OSI 계층 구조
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Headers are added
to the data at layers
6, 5, 4, 3, and 2.
Trailers are usually
added only at layer 2.
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2.1 OSI 모델(계속)
OSI 모델을 이용한 교환
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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
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2.2 OSI 모델의 계층
물리계층(physical layer)
물리적인 매체를 통하여 비트 스트림을 전송하는데
필요한 기능 제공
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Note:
The physical layer is responsible
for the movement of individual bits
from one hop (node) to the next.
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2.2 OSI 모델의 계층(계속)
물리계층의 주요 기능
장치와 전송 매체간의 인터페이스 특성과 전송 매
체 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)
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2.2 OSI 모델의 계층(계속)
데이터링크계층(data link layer)
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2.2 OSI 모델의 계층(계속)
데이터링크층의 주요 기능
프레임(frame) 구성
물리 주소 지정(송수신자 주소)
흐름 제어
오류 제어
접근 제어
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Note:
The data link layer is responsible for
moving frames from one hop (node) to
the next.
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2.2 OSI 모델의 계층(계속)
노드-대-노드 전달
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2.2 OSI 모델의 계층(계속)
네트워크계층(network layer)
패킷(packet)을 네트워크를 통하여 발신지에서 목적
지까지 전달 책임
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Note:
The network layer is responsible for
the delivery of individual packets from
the source host to the destination host.
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2.2 OSI 모델의 계층(계속)
네트워크계층 주요 기능
논리 주소 지정
라우팅
 패킷이 최종 목적지에 전달될 수 있도록 경로를 지정하거
나 교환 기능 제공
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2.2 OSI 모델의 계층(계속)
종단-대-종단 전송
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2.2 OSI 모델의 계층(계속)
전송계층(transport layer)
발신지에서 목적지(종단-대-종단)까지 전체 메시
지 전달기능 제공
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Note:
The transport layer is responsible for
the delivery of a message from one
process to another.
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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)
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2.2 OSI 모델의 계층(계속)
신뢰성 있는 종단-대-종단 메시지 전송
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2.2 OSI 모델의 계층(계속)
세션계층(session layer)
통신 시스템간의 상호 대화 설정, 유지, 동기화 기능 제
공
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2.2 OSI 모델의 계층(계속)
세션계층의 주요 기능
대화 제어(반이중, 전이중)
동기화(검사점 추가)
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2.2 OSI 모델의 계층(계속)
표현계층(presentation layer)
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2.2 OSI 모델의 계층(계속)
표현계층의 주요 기능
변환(Translation)
암호화(Encryption)
압축(Compression)
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2.2 OSI 모델의 계층(계속)
응용계층(application layer)
사용자나 소프트웨어를 네트워크에 접근 가능하도록
하는 기능 제공
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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)
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2.2 OSI 모델의 계층(계속)
계층별 요약
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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
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2.3 TCP/IP 프로토콜
TCP/IP와 OSI 모델
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2.3 TCP/IP 프로토콜(계속)
 TCP/IP 프로토콜
1. 물리계층과 데이터링크계층
 기존의 모든 표준과 기술적인 프로토콜 지원
2. 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)
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2.3 TCP/IP 프로토콜(계속)
3. 전송계층
 사용자 데이터그램 프로토콜(UDP)
 전송 제어 프로토콜(TCP)
4. 응용계층
 OSI 모델의 세션, 표현, 응용층을 합친것
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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
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2.4 주소지정
TCP/IP에서 사용하는 주소
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2.4 주소지정(계속)
TCP/IP에서 주소와 계층간의 관계
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2.4 주소지정(계속)
물리 주소
링크 주소
WAN이나 LAN에서 정의된 노드의 주소
이더넷 네트워크 인터페이스 카드(NIC) 6바이트(48
비트) 주소
유니캐스트(unicast), 멀티캐스트(multicast), 브로드
캐스트(broadcast)
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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.
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2.4 주소지정(계속)
물리 주소
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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.
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2.4 주소지정(계속)
인터넷 주소
현재 인터넷에 연결된 호스트 식별 : 32비트 주소 체계
유니캐스트(단일사용자), 멀티캐스트(그룹수신자),
브로드캐스트(네트워크 내의 모든 시스템)
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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.
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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.
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2.4 주소지정(계속)
IP 주소
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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.
132.24.75.9
An internet address in IPv4 in decimal numbers
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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.
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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.
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2.4 주소지정(계속)
포트 주소
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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.
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2.5 IP Versions
IP became the official protocol for the Internet in 1983. 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
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알림
연습문제 풀이해서
Report로 다음주까지(일주일 후)
제출해 주세요!
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