Exercise 5 |
1. (1 pt) A group of N stations share a 56 kbps slotted
ALOHA channel. Each station outputs a 2000 bit frame once every 100 sec, even if
the previous one has not yet been sent (e.g. the stations are buffered). What is
the maximum value of N?
2. (1 pt) Ten thousand airline reservation stations are
competing for the use of a single slotted ALOHA channel. The average station
makes 40 requests/hour. A slot is 250 microseconds. What is the approximate
total channel load (i.e. % of slots used of the total possible)?
3. (1 pt) Six stations, A-F, communicate using the MACA
protocol. Is it possible that two transmissions take place simultaneously?
Explain your answer.
4. (2 pt) Recover the transmitted value of C from S3 and S4.
5. (2) A seven-story building has 15 adjacent office per floor.
Each office contains a wall socket for a terminal on the front wall so the
sockets form a rectangular grid in the vertical plane with a separation of 4 m
between sockets both horizontally and vertically. Assuming that it is feasible
to run a straight cable between any pair of sockets, horizontally, vertically,
or diagonally, how many meters of cable are needed to connect all sockets using
802.3 LAN?
6. (1) An IP packet to be transmitted by Ethernet is 40 bytes long, including all its headers. If LLC is not used, is padding needed in the Ethernet frame and if so, how many padding bytes?
7. (3) From Figure 4-44b of the text, assume H7 is a host on LAN 7
and H9 is a host on LAN 9. What are the contents of the bridge frame forwarding
tables after initializing and H7 transmits a frame to H9 and H9 acknowledges the
frame receipt?
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