Network Computing Lab. (http://nclab.chonbuk.ac.kr)1

Network Programming:Syllabus

Spring 2009,

Prof. Kihyun Pyun

Evolution of Data Communication Networks (1) A key motivation

A typical key cost : communication media installation cost

Equipments are relatively cheap!

Evolution of Data Communication Networks (2) If a new technology requires a new

network infrastructure, reconsider it! Is it worth for investing a BIG money? As an example, think about the video

conferencing technologies in 1970s xDSL technologies are good examples for

success

Evolution of Data Communication Networks (3) Due to a tremendous initial investment

for a network backbone infrastructure traditionally telecommunication companies

leads the trend• E.g., FrameRelay, ATM (Asynchronous Transfer

Mode), … existing infrastructures are reused as much

as possible• However, equipments can be replaced more

easily than transmission media

5

Evolution of Data Communication Networks (4)

인터넷 서비스 제공자(ISP)

ISP

라우터 PC

서버노트북

가정망

회사망

LAN

WAN

저비용 , 이더넷

고비용 , 기존망 활용

( 케이블 모뎀 ,xDSL, etc)

인터넷 망 전체 구조

무선 AP

Evolution of Data Communication Networks (5) An example

컴퓨터 전화 모뎀 전화모뎀

( )컴퓨터 고성능 컴퓨터

컴퓨터 전화 모뎀 전화모뎀

컴퓨터 전화 모뎀 전화모뎀

인터넷

인터넷 검색 인터넷 연결을 위한 중간 다리 역할

가정

가정

가정

전화망

~ Km ,수십 수백 거리56 Kbps 이하

Evolution of Data Communication Networks (6)

컴퓨터 ADSL 모뎀분리기

(splitter)

중계기(MSLAM)분리기

(splitter)

인터넷

전화망

전화선로

300 m ,이하 거리10 Mbps 이상

가정

컴퓨터 ADSL 모뎀분리기

(splitter)

분리기(splitter)

전화선로가정

300 m ,이하 거리10 Mbps 이상

Another example

McGraw-Hill ©The McGraw-Hill Companies, Inc., 2004

Figure 16.1 Connecting devices

McGraw-Hill ©The McGraw-Hill Companies, Inc., 2004

Figure 16.2 Repeater

McGraw-Hill ©The McGraw-Hill Companies, Inc., 2004

Figure 16.3 Function of a repeater

McGraw-Hill ©The McGraw-Hill Companies, Inc., 2004

Figure 16.4 Hubs

Dummy hub : multi-port repeater

McGraw-Hill ©The McGraw-Hill Companies, Inc., 2004

Figure 16.12 Star backbone

McGraw-Hill ©The McGraw-Hill Companies, Inc., 2004 Introduction 1-13

Residential access: cable modems

Diagram: http://www.cabledatacomnews.com/cmic/diagram.html

McGraw-Hill ©The McGraw-Hill Companies, Inc., 2004 Introduction 1-14

Cable Network Architecture: Overview

home

cable headend

cable distributionnetwork (simplified)

Typically 500 to 5,000 homes

McGraw-Hill ©The McGraw-Hill Companies, Inc., 2004 Introduction 1-15

Cable Network Architecture: Overview

home

cable headend

cable distributionnetwork (simplified)

McGraw-Hill ©The McGraw-Hill Companies, Inc., 2004 Introduction 1-16

Cable Network Architecture: Overview

home

cable headend

cable distributionnetwork

server(s)

McGraw-Hill ©The McGraw-Hill Companies, Inc., 2004 Introduction 1-17

Cable Network Architecture: Overview

home

cable headend

cable distributionnetwork

Channels

VIDEO

VIDEO

VIDEO

VIDEO

VIDEO

VIDEO

DATA

DATA

CONTROL

1 2 3 4 5 6 7 8 9

FDM:

McGraw-Hill ©The McGraw-Hill Companies, Inc., 2004

Evolution of Data Communication Networks (6) A short history

Telegraphiccommunication

Telephonenetworks

Telephone andData networks

Message Voice Voice, data

ISDN(Integrated

ServicesDigital Network)

Voice, video, data

B-ISDN(Broadband

ISDN)

Internet

Voice, video, data

Data, voice by VoIP, video

Analog wirelesscommunications

Digital wirelesscommunications

GSM CDMACDMA2000,

HSDPA, …

Voice Voice Voice Voice, data Voice, video, data

ALL IP ?!Winner?

Network Computing Lab. (http://nclab.chonbuk.ac.kr)

프로토콜 스택 (Protocol Stack)

다양한 통신선과 장비가 서로 통신할 수 있도록 정한 규약들 전화선 , 동선 , 광케이블 등 국제 표준화가 필요

Layering 을 통해 복잡성을 줄임 하위 계층의 기능을 상위 계층에서 활용

19

Network Computing Lab. (http://nclab.chonbuk.ac.kr)

ISO 의 OSI reference model

OSI (Open Systems Interconnection) reference model ISO 에서 만듦 7 계층 참고 모델일 뿐 !

20

Application

Presentation

Session

Transport

Network

Data Link

Physical

Introduction 1-21

Internet protocol stack application: supporting network

applications FTP, SMTP, STTP

transport: host-host data transfer TCP, UDP

network: routing of datagrams from source to destination IP, routing protocols

link: data transfer between neighboring network elements PPP, Ethernet

physical: bits “on the wire”

application

transport

network

link

physical

Introduction 1-22

Protocol layering and data

Each layer takes data from above adds header information to create new data unit passes new data unit to layer below

applicationtransportnetwork

linkphysical

applicationtransportnetwork

linkphysical

source destination

M

M

M

M

Ht

HtHn

HtHnHl

M

M

M

M

Ht

HtHn

HtHnHl

message

segment

datagram

frame

스택구조로 사용먼저 넣은 것이 가장 늦게 나옴

Network Computing Lab. (http://nclab.chonbuk.ac.kr)

토론 마당

새로운 선 , 예들 들면 USB 선에 연결된 마우스를 인터넷에서 접속하는 것이 가능할까 ? 어떻게 ?

혹은 CDMA 망에 인터넷은 어떻게 ?

23

CDMA

Physical

IP

TCP

CDMA

Physical

Network Computing Lab. (http://nclab.chonbuk.ac.kr)

프로토콜 예제

24

Ethernet

UTP

TCP/IP

X.25/…

Coaxial

TCP/IP

WCDMA/Wibro

Wireless channel

TCP/IP

Ethernet

UTP

TCP/IP

X.25/…

Coaxial

TCP/IP

WCDMA/Wibro

Wireless channel

TCP/IP

하부망 특정 프로토콜( 예 : ARP, RARP)

하부망 특정 프로토콜( 예 : 기지국 찾기 , …)

네트워크 프로그래밍은 넓은 관점에서는 위의 모든 프로토콜 영역에 적용할 수 있어야 함 .그러나 하부망 특정 프로토콜 영역은 ( 소켓프로그래밍에서 Raw 패킷 ) 이 과목에서 주로 다루지 않음

Network Computing Lab. (http://nclab.chonbuk.ac.kr)

고려해야 할 프로토콜들

TCP 오류없는 데이터 전송 보장

UDP 효율적인 데이터 전송 ( 패킷 소실 가능 )

응용 프로토콜 FTP, Telnet, …

25

TCP UDP

IP

FTP HTTP RIPOSPF