Computer Science 825
                         Quiz 5              Name _______________________

1. A token bus system (not IEEE 802.4) works like this. When the token
   arrives at a station a timer is reset to 0.  The station then transmits
   priority 6 frames unitl the timer reaches T6. It then switches to
   priority 4 until the timer reaches T4.  This algorithm is repeated for
   with priority 2 and 0. If all stations use the values of 60, 100, 130,
   150 for T6 through T0 what percent of the bandwidth will be dedicated
   to class 4 (assume all stations have an infinite backlog of each class.)










2. In IEEE 802.4 the value TRT4 specifies:

   a. The time dedicated to class  b. The time left for transmission
      4 traffic at each token         of class 4 data when the time of
      possession.                     the last token rotation is subtracted
                                      from TRT 4


   c. The time left for transmission    d. Both a. and c. specify the
      of class 4 data when the time of     same value.
      the last token rotation + time
      spent transmitting class 6 is
      subtracted from TRT 4

3. For the IEEE token bus match the control packets with the conditions
   underwhich they are used. (Some answers may or may not be used
   multiple times and some may or may not be used at all.)

   ____ a. A station is powered up, listens     1. SOLICIT_SUCCESSOR_2
           for the token and doesn't hear one.
                                                2. WHO_LEADS
   ____ b. A station wishes to leave the net.
                                                3. WHO_FOLLOWS

   ____ c. A station transmits the token twice  4. RESOLVE_CONTENTION
           without hearing its successor
           transmit a token or a packet.        5. CLAIM_TOKEN

   ____ d. A station wishes to invite a new     6. SOLICIT_SUCCESSOR
           station to enter the network.
                                                7. SET_SUCCESSOR
   ____ e. A station recognizes a WHO_FOLLOWS
           packet specifying its predecessors   8. WHO_KNOWS
           address.
                                                9. LEAD_FOLLOW_OR_
   ____ f. A station transmits WHO_FOLLOWS         GET_OFF_THE_DAMN_BUS
           and receives no response.


4. The maximum length of an ethernet segment is:

   a. 5 meters                   b. 5 miles

   c. 500 miles                  d. 500 meters

5. Which of the following best characterizes the difference between
   an ethernet bridge and a repeater.

   a. Both bridges and repeaters  b. Bridges forward all traffic but
      forward all traffic to         repeaters attempt to forward only
      connected segments.            those packets that need to go to
                                     the connected segment.

   c. Repeaters forward all traffic but
      bridges attempt to forward only
      those packets that need to go to
      the connected segment.



6. a. In a token ring LAN is the sender xor 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.





7. Suppose bit transmission rate is 4,000,000 b.p.s and signal propogation is
   200,000 KM / sec. How long must a cable be to hold an entire 24 bit token.