1. Performance Metrics Neil Tang 9/10/2008
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2. Outline Bandwidth (Throughput) Latency (Delay) Delay  Bandwidth
Jitter
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3. Bandwidth (Throughput)
Bandwidth: the number of bits that can be transmitted from one end to another in a certain period of time.
Link Bandwidth VS. End-to-End Bandwidth
Why “Width”: Each bit can be looked as a pulse of some “width”.
Another Meaning of Bandwidth: the width of a frequency (spectrum) band.
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4. Latency (Delay)
Latency: how long it takes for a message to travel from one end to another.
Link Latency VS. End-to-End Latency
Latency:
Latency = Propagation delay + Transmit delay + Queuing delay
Propagation delay = Distance / Speed-of-Light
Transmit delay = PacketSize / Bandwidth
Round Trip Time (RTT) (only includes propagation delay)
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5. Effective Throughput TransferTime = one-way latency + setup time
Effective Throughput = TransferSize/TransferTime
TransferSize only includes DATA bits
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6. Delay  Bandwidth
Delay  Bandwidth : The number of bits the channel can hold (the volume of the pipe).
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7. Jitter The bandwidth needs may vary.
Jitter: It is the variation in packet latency and caused by queuing delay.
Solution: Buffering at the receiver
Network
Interpacket gap
Packet
source
sink 1 2 3 4
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