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Computer Networksand Internets

Spring 2005

Assistant Professor JainShing Liu

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NetworksNetworks

What is a network? electric net, telephone net, computer net

Network architecturesNetwork payload (voice net, data network)Network protocolsCircuit-switching vs. packet switching

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NetworksNetworks

Telephone net

EndOffice

PBX

Ext. 200

555-6089 (10 lines)

555-6201

555EndOffice

400-1547 400-2016

400

EndOffice

900

tandemswitchtandem

switchCarrier network

trunk

twist pair

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NetworksNetworks

Computer net

LAN

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You Will LearnYou Will Learn

Using and Building Internet Applications

(Part I)Motivation and toolsNetwork programming and Applications

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You Will Learn (ctn.)You Will Learn (ctn.)

Data Transmission (Part II)Transmission mediaLocal asynchronous communication (RS-232)Long-Distance communication

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You Will Learn (ctn.)You Will Learn (ctn.)Packet Transmission (Part III)

Packet, frames, and error detectionLAN technologiesWAN technologiesProtocols and layering

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You Will Learn (ctn.)You Will Learn (ctn.)Internetworking (Part IV)

Concepts and ProtocolsInternet Protocol (IP) datagram and ForwardingAddress binding (ARP)Internet control messages (ICMP)User Datagram Protocol (UDP)Transmission Control Protocol (TCP)Network Address Translation (NAT)Internet Routing

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You Will Learn (ctn.)You Will Learn (ctn.)

Network applications (Part V)Client-server paradigm, Socket InterfaceDomain name system (DNS)Voice over IP (VoIP)E-mail, File transfer (FTP), Remote login

(TELNET)Email transfer (SMTP)Web technologies and protocolsSNMP

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What You Will NOT LearnWhat You Will NOT Learn

Commercial aspectsProductsVendorsPricesNetwork operating systems

How to purchase / configure / operateHow to design / implement protocol software

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Ch 1. Introduction

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Growth of the InternetGrowth of the Internet

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Growth of Computer Networking

Growth of Computer Networking

Computer networks are everywhereAdvertising, 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

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Ch 2. Motivation and Tools

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Motivation for NetworkingMotivation for Networking

Information sharingResource sharing

Computing powerPeripheral devices such as a printer or a diskHuman power

Interaction among cooperative application programs

E.g., earthquake alarm

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ConfigurationsConfigurations

IP addressSubnet MaskDefault gatewayDNS server

Internet

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Internet

Internet ToolsInternet Tools

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Internet ToolsInternet ToolsPing

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=249Reply from 163.23.1.73: bytes=32 time=2ms TTL=249Reply from 163.23.1.73: bytes=32 time=2ms TTL=249Reply from 163.23.1.73: bytes=32 time=1ms TTL=249Ping 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

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Internet ToolsInternet 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 of30 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.