1. 1 Computer Networks and Internets Spring 2005 Assistant Professor JainShing Liu

2. 2 Networks  What is a network? electric net, telephone net, computer net  Network architectures  Network payload (voice net, data network)  Network protocols  Circuit-switching vs. packet switching

3. 3 Networks  Telephone net End Office PBX Ext. 200 555-6089 (10 lines) 555-6201 555 End Office 400-1547400-2016 400 End Office 900 tandem switch tandem switch Carrier network trunk twist pair

4. 4 Networks  Computer net LAN

5. 5 You Will Learn  Using and Building Internet Applications (Part I) Motivation and tools Network programming and Applications

6. 6 You Will Learn (ctn.)  Data Transmission (Part II) Transmission media Local asynchronous communication (RS-232) Long-Distance communication

7. 7 You Will Learn (ctn.)  Packet Transmission (Part III) Packet, frames, and error detection LAN technologies WAN technologies Protocols and layering

8. 8 You Will Learn (ctn.)  Internetworking (Part IV) Concepts and Protocols Internet Protocol (IP) datagram and Forwarding Address binding (ARP) Internet control messages (ICMP) User Datagram Protocol (UDP) Transmission Control Protocol (TCP) Network Address Translation (NAT) Internet Routing

9. 9 You Will Learn (ctn.)  Network applications (Part V) Client-server paradigm, Socket Interface Domain name system (DNS) Voice over IP (VoIP) E-mail, File transfer (FTP), Remote login (TELNET) Email transfer (SMTP) Web technologies and protocols SNMP

10. 10 What You Will NOT Learn  Commercial aspects Products Vendors Prices Network operating systems  How to purchase / configure / operate  How to design / implement protocol software

11. 11 Ch 1. Introduction

12. 12 Growth of the Internet

13. 13 Growth of Computer Networking  Computer networks are everywhere Advertising, shopping, …  An entire industry has emerged that develops networking technologies, products, and services  Produces a strong demand in all jobs for people with more networking expertise  Programmers are expected to design network application software

14. 14 Ch 2. Motivation and Tools

15. 15 Motivation for Networking  Information sharing  Resource sharing Computing power Peripheral devices such as a printer or a disk Human power  Interaction among cooperative application programs E.g., earthquake alarm

16. 16 Configurations  IP address  Subnet Mask  Default gateway  DNS server Internet

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18. 18

19. 19 Internet Internet Tools

20. 20 Internet Tools  Ping ping 163.23.1.73 (or ping mail.dyu.edu.tw) Pinging 163.23.1.73 with 32 bytes of data: Reply from 163.23.1.73: bytes=32 time=2ms TTL=249 Reply from 163.23.1.73: bytes=32 time=1ms TTL=249 Ping statistics for 163.23.1.73: Packets: Sent = 4, Received = 4, Lost = 0 (0% loss), Approximate round trip times in milli-seconds: Minimum = 1ms, Maximum = 2ms, Average = 1ms

21. 21 Internet Tools  traceroute (tracert for MS Windows) tracert www.nctu.edu.tw Tracing route to mail.dyu.edu.tw [163.23.1.73] over a maximum of 30 hops: 1 <1 ms <1 ms <1 ms 2sch-g.pu.edu.tw [140.128.19.254] 2 <1 ms <1 ms <1 ms ssrccc-mgt.pu.edu.tw [140.128.20.254] 3 1 ms <1 ms <1 ms frouter1.pu.edu.tw [140.128.30.253] 4 2 ms 1 ms 1 ms 140.128.251.42 5 2 ms 2 ms 2 ms 140.128.251.33 6 13 ms 12 ms 13 ms 163.23.32.254 7 2 ms 1 ms 2 ms mail.dyu.edu.tw [163.23.1.73] Trace complete.