文档介绍：WORKS
FOURTH EDITION
PROBLEM SOLUTIONS
ANDREW S. TANENBAUM
Vrije Universiteit
Amsterdam, herlands
PRENTICE HALL PTR
UPPER SADDLE RIVER, NJ 07458
© 2003 Pearson Education, Inc.
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ISBN 0-13-046002-8
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PROBLEM SOLUTIONS 1
SOLUTIONS TO CHAPTER 1 PROBLEMS
1. The dog can carry 21 gigabytes, or 168 gigabits. A speed of 18 km/hour
equals km/sec. The time to travel distance x km is x/ = 200x sec,
yielding a data rate of 168/200x Gbps or 840/x Mbps. For x< km, the
dog has a higher rate than munication line.
2. The LAN model can be grown incrementally. If the LAN is just a long cable.
it cannot be brought down by a single failure (if the servers are replicated) It
is probably cheaper. It provides puting power and better interactive
interfaces.
3. A transcontinental fiber link might have many gigabits/sec of bandwidth, but
the latency will also be high due to the speed of light propagation over
thousands of kilometers. In contrast, a 56-kbps modem calling puter in
the same building has low bandwidth and low latency.
4. A uniform delivery time is needed for voice, so the amount of jitter in -
work is important. This could be expressed as the standard deviation of the
delivery time. Having short delay but large variability is actually worse than
a somewhat longer delay and low variability.
5. No. The speed of propagation is 200,000 km/sec or 200 meters/µsec. In 10
µsec the s