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Computer Networks and Internets. Spring 2005 Assistant Professor JainShing Liu. 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. Networks.
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Computer Networksand Internets Spring 2005 Assistant Professor JainShing Liu
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
Networks • Telephone net tandem switch tandem switch Carrier network trunk End Office 900 End Office End Office 400 555 twist pair 555-6089 (10 lines) PBX 400-1547 400-2016 555-6201 Ext. 200
LAN Networks • Computer net
You Will Learn • Using and Building Internet Applications (Part I) • Motivation and tools • Network programming and Applications
You Will Learn (ctn.) • Data Transmission (Part II) • Transmission media • Local asynchronous communication (RS-232) • Long-Distance communication
You Will Learn (ctn.) • Packet Transmission (Part III) • Packet, frames, and error detection • LAN technologies • WAN technologies • Protocols and layering
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
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
What You Will NOT Learn • Commercial aspects • Products • Vendors • Prices • Network operating systems • How to purchase / configure / operate • How to design / implement protocol software
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
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
Configurations • IP address • Subnet Mask • Default gateway • DNS server Internet
Internet Tools Internet
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=2ms TTL=249 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
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.