Homework #4

All submitted work must be your own contribution and nobody else's! Collaboration in homework is not allowed.

1. [15 points]Text, Problem 6-10.
2. [15 points]Text, Problem 6-17.
3. [10 points]Text, Problem 6-38.
4. [15 points]Text, Problem 6-40 (b).
5. [15 points]Text, Problem 6-52.
6. [15 points]Suppose A, B, and C all make their first carrier sense, as part of an attempt to transmit, while a fourth station D is transmitting. Draw a timeline showing one possible sequence of transmissions, attempts, collisions, and binary exponential backoff choices. Your timeline should also meet the following criteria: (i) initial transmission attempts should be in the order A, B, C, but successful transmissions should be in the order C, B, A and (ii) there should be at least four collisions.
7. [15 points] Suppose the round trip propagation delay for Ethernet is 46.4us. This yields a minimum packet size 512 bits (464 bits corresponding to propagation delay + 48 bits of jam signal).
   • What happens to the minimum packet size if the delay time is held constant, and the transmission rate rises to 100Mbps?
   • What are the drawbacks to so large a minimum packet size?
   • If compatibility were not an issue, how might the specification be written so as to permit a smaller minimum packet size?

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