notes10 - TELENET 2120 Network Performance Review Asst....

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1 TELENET 2120 Network Performance Review Asst. Prof. Joseph Kabara, Ph.D Graduate Program in Telecommunications and Networking University of Pittsburgh 2 Review TELENET 2120: Network Performance Course Objective To develop the modeling, mathematical and programming tools necessary to determine the performance of computer systems and communication networks. Performance Study: Estimating one or more metrics via 1. measurement, 2. simulation 3. analysis Metrics are usually statistical quantities Throughput, Response Time, Availability, Call Blocking, etc 3 Review TELENET 2120: Network Performance Why Performance Modeling ? Determining network performance is a key element in “Design, Operation, and Management” – Set system parameters and design tradeoffs Example-1: How many terminals can connect to a mainframe computer system ? Example-2: Determine buffer requirements in a switch. Example-3: How should adaptive windowing work ? Example-4: What switch/router to buy ? Example-5: If add 40 computers on a LAN to campus backbone, what is the delay on the backbone going to be?
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2 4 Review TELENET 2120: Network Performance General Goals Specifying performance requirements Evaluating design alternatives Comparing two or more systems System tuning Bottleneck identification Workload characterization Capacity planning Forecasting 5 Review TELENET 2120: Network Performance History of Performance Modeling Orginated with Erlang in 1917 – Studied circuit switched telephone networks – determine how many operators to keep call blocking at reasonable level Kleinrock, Cerf studied data networks in 60’s – Studied delay in ARPANET Sauer, Chandy – computer systems in 60’s – Studied how disk drives interact with computer processing power, time sharing strategies 6 Review TELENET 2120: Network Performance Metrics, Parameters, Factors •M e t r i c s – Criteria to used to evaluate performance of a system Parameters – System parameters • h/w and s/w parameters. – Workload parameters • characteristics of user requests •F a c t o r s – Parameters to be varied during a study. – Values can be varied to different levels (i.e., numerical values) Metrics are usually statistical quantities
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3 7 Review TELENET 2120: Network Performance Performance Metrics Moments – Response time – Throughput – Utilization – Queue length Probabilities – Call blocking rate – Packet loss rate – Packet out of order rate – Distribution of response time – Bit error rates – Packet error rates Display as graph or table 8 Review TELENET 2120: Network Performance Performance Techniques Three basic techniques for performance analysis 1. Measurements ¾ Gather Experimental Data from prototype or existing system 2. Simulation ¾ Experiment with computer model of system 3. Queueing Theory ¾ Analytical model of system Complementary tools Should cross check them 9 Review TELENET 2120: Network Performance Measurements Run experiments on existing system or prototype.
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notes10 - TELENET 2120 Network Performance Review Asst....

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