A client sends a 128-byte request to a server located 100 km away over a 1-gigabit optical fiber. What is the efficiency of the line during the remote procedure call? We assume the speed of light in fiber optics is 200 km/msec, and treat 128 bytes as 1000 bits.

Suppose a file of 10,000 bytes is to be sent over a line at 2400 bps. A. Calculate the overhead in bits and time in using asynchronous communication. Assume one start bit and a stop element of length one bit, and 8 bits to send the byte itself for each character. The 8-bit character consists of all data bits, with no parity bit. B. Calculate the overhead in bits and time using synchronous communication. Assume that the data are sent in frames. Each frame consists of 1000 characters = 8000 bits and an overhead of 48 control bits per frame. C. What would the answers to parts (a) and (b) be for a file of 100,000 characters?

A processor uses a serial link to communicate with a keyboard for word processing. A typist using this keyboard can type at rates peaking at 120 words per minute, where a word is 6 characters (including spaces and punctuation). The characters will be transmitted from the keyboard in 8-bit ASCII with one stop bit and no parity. Only consider these and no special characters. The programmer writes setup and polling service routines based on a minimum baud rate, but then finds that the keyboard will only interface at 19.2 Kbaud. Will the polling service routine have to change? Why or why not? Baud Rates 300 600 1200 2400 4800 9600 19200

Suppose a file of 10,000 bytes is to be sent over a line at 2400 bps. A. Calculate the overhead in bits and time in using asynchronous communication. Assume one start bit and a stop element of length one bit, and 8 bits to send the byte itself for each character. The 8-bit character consists of all data bits, with no parity bit. B. Calculate the overhead in bits and time using synchronous communication. Assume that the data are sent in frames. Each frame consists of 1000 characters = 8000 bits and an overhead of 48 control bits per frame. C. What would the answers to parts (a) and (b) be for a file of 100,000 characters?

4. In this problem, you will derive the efficiency of a CSMA/CD-like multiple access protocol. In this protocol, time is slotted and all adapters are synchronized to the slots. Unlike slotted ALOHA, however, the length of a slot (in seconds) is much less than a frame time (the time to transmit a frame). Let S be the length of a slot. Suppose all frames are of