Computer Science 825
                         Quiz 5              Name _______________________

1. Two standard measures of network performance are sustained throughput
   and mean packet delay. High sustained throughput is good and low mean
   packet delay is good.  For each of the following select the answer that
   bests compares CSMA/CD with token passing.

   a. Sustained throughput at very high loads
      1. CSMA/CD is better          2. Token passing is better
      3. No measureable difference

   b. Packed delay at very high loads
      1. CSMA/CD is better          2. Token passing is better
      3. No measureable difference

   c. Sustained throughput at very low loads
      1. CSMA/CD is better          2. Token passing is better
      3. No measureable difference

   d. Packet delay at very low loads
      1. CSMA/CD is better          2. Token passing is better
      3. No measureable difference

2. Answer the following T or F.

   ___ a. Increasing the bit rate of a CSMA/CD LAN will shorten the length
          of the contention interval and thus make the efficiency of the
          LAN higher.

   ___ b. Increasing the average packet size will tend to make the efficiency
          of a CSMA CD LAN higher.

   ___ c. A token ring lan must be physically long enough to hold an entire
          packet in transmission.

   ___ d. A token ring lan must be physically long enough to hold an entire
          token.

3. Suppose a token bus system has 3 priority classes 3, 2, and 1. The token
   holding times for the classes are respectively 1000us 300us and 100us.
   What percent of the bandwidth is dedicated to class 2 traffic?






4. a. In a token ring LAN is the sender or receiver responsible for removing
      a data packet from the ring?


   b. What is the BIGGEST problem associated with having the other party
      perform the function.





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3. For the IEEE token bus match the control packet that will be generated
   under each of the following conditions.

   ____ a. A station crashes or is powered off  1. SOLICIT_SUCCESSOR_2
           just after receiving the token.
                                                2. WHO_FOLLOWS
   ____ b. A station wishes to leave the net.
                                                3. SET_SUCCESSOR

   ____ c. A collision occurs when two          4. RESOLVE_CONTENTION
           stations try to join the net at
           the same time.                       5. CLAIM_TOKEN

   ____ d. A station wishes to invite a new     6. SOLICIT_SUCCESSOR
           station to enter the network.

   ____ e. A station recognizes a WHO_FOLLOWS
           packet specifying its predecessors
           address.