Network Computing Lab. ( 1 Network Programming: Syllabus Spring 2009, Prof. Kihyun Pyun

Evolution of Data Communication Networks (1) r A key motivation r A typical key cost : communication media installation cost r Equipments are relatively cheap!

Evolution of Data Communication Networks (2) r If a new technology requires a new network infrastructure, reconsider it! m Is it worth for investing a BIG money? m As an example, think about the video conferencing technologies in 1970s m xDSL technologies are good examples for success

Evolution of Data Communication Networks (3) r Due to a tremendous initial investment for a network backbone infrastructure m traditionally telecommunication companies leads the trend E.g., FrameRelay, ATM (Asynchronous Transfer Mode), … m 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 서버 노트북 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) r An example

Evolution of Data Communication Networks (6) 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 Star backbone

McGraw-Hill©The McGraw-Hill Companies, Inc., 2004 Introduction1-13 Residential access: cable modems Diagram:

McGraw-Hill©The McGraw-Hill Companies, Inc., 2004 Introduction1-14 Cable Network Architecture: Overview home cable headend cable distribution network (simplified) Typically 500 to 5,000 homes

McGraw-Hill©The McGraw-Hill Companies, Inc., 2004 Introduction1-15 Cable Network Architecture: Overview home cable headend cable distribution network (simplified)

McGraw-Hill©The McGraw-Hill Companies, Inc., 2004 Introduction1-16 Cable Network Architecture: Overview home cable headend cable distribution network server(s)

McGraw-Hill©The McGraw-Hill Companies, Inc., 2004 Introduction1-17 Cable Network Architecture: Overview home cable headend cable distribution network Channels VIDEOVIDEO VIDEOVIDEO VIDEOVIDEO VIDEOVIDEO VIDEOVIDEO VIDEOVIDEO DATADATA DATADATA CONTROLCONTROL FDM:

McGraw-Hill©The McGraw-Hill Companies, Inc., 2004 Evolution of Data Communication Networks (6) A short history Telegraphic communication Telephone networks Telephone and Data networks MessageVoiceVoice, data ISDN (Integrated Services Digital Network) Voice, video, data B-ISDN (Broadband ISDN) Internet Voice, video, data Data, voice by VoIP, video Analog wireless communications Digital wireless communications GSMCDMA CDMA2000, HSDPA, … Voice Voice, dataVoice, video, data ALL IP ?! Winner?

Network Computing Lab. ( 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. ( 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 m FTP, SMTP, STTP  transport: host-host data transfer m TCP, UDP  network: routing of datagrams from source to destination m IP, routing protocols  link: data transfer between neighboring network elements m 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 application transport network link physical application transport network link physical source destination M M M M H t H t H n H t H n H l M M M M H t H t H n H t H n H l message segment datagram frame 스택구조로 사용 먼저 넣은 것이 가장 늦 게 나옴

Network Computing Lab. ( 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. ( 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. ( 고려해야 할 프로토콜들  TCP  오류없는 데이터 전송 보장  UDP  효율적인 데이터 전송 ( 패킷 소실 가능 )  응용 프로토콜  FTP, Telnet, … 25 TCPUDP IP FTPHTTPRIP OSPF