Some books quote the maximum size of an Ethernet frame as 1522 bytes instead of 1500 bytes. Are they wrong? Explain your answer.

An IP packet to be transmitted by Ethernet is 60 bytes long, including all its headers. If LLC is not in use, is padding needed in the Ethernet frame, and if so, how many bytes?

Name two networks that allow frames to be packed back-to-back. Why is this feature worth having?

Two CSMA/CD stations are each trying to transmit long (multiframe) files. After each frame is sent, they contend for the channel, using the binary exponential backoff algorithm. What is the probability that the contention ends on round k, and what is the mean number of rounds per contention period?

A 1-km-long, 10-Mbps CSMA/CD LAN (not 802.3) has a propagation speed of 200 m/$\mu$sec. Repeaters are not allowed in this system. Data frames are 256 bits long, including 32 bits of header, checksum, and other overhead. The first bit slot after a successful transmission is reserved for the receiver to capture the channel in order to send a 32-bit acknowledgement frame. What is the effective data rate, excluding overhead, assuming that there are no collisions?

Sketch the Manchester encoding on a classic Ethernet for the bit stream 0001110101.

What is the baud rate of classic 10-Mbps Ethernet?

A seven-story office building has 15 adjacent offices per floor. Each office contains a wall socket for a terminal in 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

(a) A star configuration with a single router in the middle?

(b) A classic 802.3 LAN?

Six stations, A through F, communicate using the MACA protocol. Is it possible for two transmissions to take place simultaneously? Explain your answer.

Consider five wireless stations, A, B, C, D, and E. Station A can communicate with all other stations. B can communicate with A, C and E. C can communicate with A, B and D. D can communicate with A, C and E. E can communicate A, D and B.

(a) When A is sending to B, what other communications are possible?

(b) When B is sending to A, what other communications are possible?

(c) When B is sending to C, what other communications are possible?

A store sells packages of comic books with a poster. $$ \begin{array}{|c|} \hline \text{1 poster + 6 comics}\\ \mathrm{$12.75}\\ \text{OR}\\ \text{1 poster + 13 comics}\\ \mathrm{$19.75}\\ \hline \end{array} $$ Write a linear function in the form y = mx + b that represents the cost, y, of a package containing any number of comic books, x.

Suppose that the three-statement while loop near the end of protocol 6 was removed from the code. Would this affect the correctness of the protocol or just the performance? Explain your answer.

If the procedure between in protocol 5 checked for the condition a $\le$ b $\le$ c instead of the condition a $\le$ b<c, would that have any effect on the protocol’s correctness or efficiency? Explain your answer.

What is the difference, if any, between the demodulator part of a modem and the coder part of a codec? (After all, both convert analog signals to digital ones.)