Lecture 1 Overview - Data Communications, Data Networks ...

1 8/25/2013 CPE400/ECG600 Fall 20131 data AND COMPUTER COMMUNICATIONSMei YangBased on Lecture slides by William StallingsLecture 1 Overview - data Communications, data Networks , and the Internet1 OUTLINE| data Communications and networking for Today s Enterprise|A Communications Model| data Communications| Networks |The Internet28/25/2013 CPE400/ECG600 Fall 20132 DATACOMMUNICATIONS ANDNETWORKING FORTODAY SENTERPRISE|TrendsyThree forces that drive the architecture and evolution of data communications and networking Development of new services Advances in technologyTraffic growth at a high & steady rate348/25/2013 CPE400/ECG600 Fall 20133 TECHNOLOGYTRENDS|Four technology trends are particularly notable.

2 YThe trend toward faster and cheaper, both in computing and communications, continuesyBoth voice-oriented telecommunications Networks and data Networks are more intelligent than everyThe Internet, the Web, and associated applications have emerged as dominant features of both business and personal worldyThere have been a trend toward ever-increasing mobility for decades5 TECHNOLOGYTRENDS(CONT D)68/25/2013 CPE400/ECG600 Fall 20134 SIGNIFICANTCHANGES INREQUIREMENTS|Emergence of high-speed LANsyExamples: centralized server farms, power workgroups, and high-speed local backbone|Corporate WAN needsyDriven by the needs of centralized data processing model and distribution of multiple offices.

3 |Digital electronics7 CONVERGENCE|The merger of previously distinct telephony and information technologies and markets|Layers: applications|these are seen by the end users enterprise services|services the information network supplies to support applications infrastructure| communication links available to the enterprise88/25/2013 CPE400/ECG600 Fall 20135 CONVERGENCELAYERS9 BENEFITSE fficiency better use of existing resources, and implementation of centralized capacity planning, asset and policy managementEffectiveness the converged environment provides users with flexibility, rapid standardized service deployment and enhanced remote connectivity and mobilityTransformation enables the enterprise-wide adoption of global standards and associated service levels|Convergence benefits include.

4 108/25/2013 CPE400/ECG600 Fall 20136A COMMUNICATIONSMODEL11 COMMUNICATIONSTASKST ransmission system utilization AddressingInterfacingRoutingSignal generationRecoverySynchronizationMessage formattingExchange managementSecurityError detection and correctionNetwork managementFlow control128/25/2013 CPE400/ECG600 Fall 20137 DATACOMMUNICATIONSMODEL13|The basic building block of any communications facility is the transmission line. |The business manager is concerned with a facility providing the required capacity, with acceptable reliability, at minimum cost. CapacityTransmissionLineTransmission LinesReliabilityCost148/25/2013 CPE400/ECG600 Fall 20138 TRANSMISSIONMEDIUM|selection is a basic choiceyinternal use entirely up to businessylong-distance links made by carrier|rapid technology advances change mixyfiber opticywireless15 networking |growth of number & power of computers is driving need for interconnection|also seeing rapid integration of voice, data , image & video technologies|two broad categories of communications Networks .

5 YLocal Area Network (LAN)yWide Area Network (WAN)168/25/2013 CPE400/ECG600 Fall 20139 WIDEAREANETWORKS|span a large geographical area|cross public rights of way|rely in part on common carrier circuits|alternative technologies used include:yleased lineycircuit switchingypacket switching: , frame relayyAsynchronous Transfer Mode (ATM)17188/25/2013 CPE400/ECG600 Fall 201310 CIRCUITSWITCHING|uses a dedicated communications path established for duration of conversation|comprising a sequence of physical links|with a dedicated logical channel| telephone network19 PACKETSWITCHING| data sent out in sequence of small chunks (packets)

6 |packets passed from node to node between source and destination|used for terminal to computer and computer to computer communications208/25/2013 CPE400/ECG600 Fall 201311 FRAMERELAY|Motivationypacket switching systems have large overheads to compensate for errorsymodern systems are more reliable, errors can be caught in end system|Frame Relay yprovides higher speeds with most error control overhead removed, up to 2 Mbps21 ASYNCHRONOUSTRANSFERMODE|evolution of frame relay and circuit switchingyfixed packet (called cell) length via virtual channelsywith little overhead for error controlybandwidth from 10 Mbps to Gbpsyconstant data rate using packet switching technique with multiple virtual circuits228/25/2013 CPE400/ECG600 Fall 201312 LOCALAREANETWORKS(LAN)23 METROPOLITANAREANETWORKS(MAN)

7 248/25/2013 CPE400/ECG600 Fall 201313 THE INTERNET|Internet evolved from ARPANET yfirst operational packet networkyapplied to tactical radio & satellite nets alsoyhad a need for interoperabilityyled to standardized TCP/IP protocols25 INTERNET ELEMENTS268/25/2013 CPE400/ECG600 Fall 201314 INTERNET ARCHITECTURE27 EXAMPLE CONFIGURATION288/25/2013 CPE400/ECG600 Fall 201315 SUMMARY|Trends challenging data communications:ytraffic growthydevelopment of new servicesyadvances in technology|Transmission mediumsyfiber opticywireless|Network categories:yWANyLAN|Internetyevolved from the ARPANETyTCP/IP foundation29