Packet Walk Through and Statistical Multiplexing

Introductory TopicsEE122 TAs past and present

ComprehensionHow fast is my speech?~1000 ft/s (speed of sound)~125 words/minuteWhat about Steve Woodmore?~1000 ft/s (speed of sound)~640 words/minute (maybe)How long would it take:to hear me or Steve, if we shout Help (very loudly) from Stanford? (~40 miles [~200,000 feet] away)me or Steve to dictate War and Peace? (~600,000 words)N.B. If-I-am-actually-speaking-far-too-fasto r w a y t o o s l o w l y, let me know!propagation delaytransmission delayTransmission DelayTransmission DelayTime taken to push data onto linkMeasured fromwhen the first bit of data is pushed onto the link towhen the last bit of data is pushed onto the linkLimited by the Bandwidth of the linkPropagation DelayPropagation DelayTime taken by data to traverse a linkLimited by the speed of lightLatency of a link is the propagation delay to traverse the linkTransmission and Propagation DelayPropagation delay Transmission delayABABPacket7Queuing DelayQueuing DelayTime a packet spends in a buffer/queue of a switch / routerOnly when arrival rate > service rateEspecially when packet arrivals are burstyBurstyNot BurstyABCTransmission delay doublesBrown packet waits for half the trans. delay of blue packetQueuing DelayQueuing delay ABCTransmission delay doublesNo Queuing DelayBrown packet does not have to waitEnd-to-End DelayPropagation delayTransmission delayQueuing delayProcessing delaySum of all delaysEnd-to-End Delay+Round Trip Time (RTT)Time for packet to reach a destination AND a response to returnABPacketResponseWorksheetPropagation delay Transmission delayABSize of transfer / Bandwidth of linkPhysical distance / Speed of lightAB16Sharing in Circuit Switching

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