problem 1: The given character encoding is employed in a data link protocol: A: 01000111; B: 11100011; FLAG: 01111110; ESC: 11100000. Show the bit sequence transmitted in binary for the four-character frame: A B ESC FLAG when each of the given framing methods is employed:
a) Character count.
b) Flag bytes with byte stuffing.
c) Starting and ending flag bytes with bit stuffing.
problem 2: When bit stuffing is employed, is it possible for the loss, insertion or modification of a single bit to cause an error not detected by the checksum? If not, why not? If so, how? Does the checksum length perform a role here?
problem 3: Determine the remainder obtained by dividing x7 + x5 + 1 by the generator polynomial x3 + 1?
problem 4: A bit stream 10011101 is transmitted by using the standard CRC method describeed in the text. The generator polynomial is x3 + 1. Show the actual bit string transmitted. Assume the third bit from the left is inverted throughout the transmission. Show that this error is detected at receiver's end.
problem 5: Imagine a sliding window protocol by using so many bits for sequence numbers which wraparound never takes place. What relations must hold among the four window edges and the window size, which is constant and the similar for both the sender and receiver.