In a data link protocol, the frame delimiter flag is given by 0111. Assuming that bit stuffing is employed, the transmitter sends the data sequence 01101101 as:
A. 01101101
B. 01101100
C. 01101101
D. 01101100
GATE 2004 · Computer Networks · Bit Stuffing · medium
Answer: The transmitted bit-string is A. 01101101
Scan the data sequence for runs of consecutive 1s: Data: 0 1 1 0 1 1 0 1
Position 1: 0 -> count = 0
Position 2: 1 -> count = 1
Position 3: 1 -> count = 2
Position 4: 0 -> count = 0, no stuffing needed
Position 5: 1 -> count = 1
Position 6: 1 -> count = 2
Position 7: 0 -> count = 0, no stuffing needed
Position 8: 1 -> count = 1
Maximum consecutive 1s = 2 (less than 3), so no stuffing is needed.
Determine transmitted sequence: Since no three consecutive 1s appear in 01101101, the transmitted sequence is the same as the data: 01101101.