In bit stuffing at the Data Link Layer, a zero is stuffed after how many consecutive 1s in the data payload to prevent accidental flag generation (flag = 01111110)?
To prevent accidental matching with the flag byte 01111110 (which has 6 consecutive 1s), a '0' is inserted after every 5 consecutive 1s in the data stream.
A bit stream 011111101111110 is transmitted using bit stuffing. What is the output bit stream after bit stuffing?
Bit stream: 0 11111 10 11111 10. After 1st sequence of five 1s: insert 0 -> 011111010. After 2nd sequence of five 1s: insert 0 -> 011111010. Result = 01111101011111010.
If the character 'ESC' is part of the data in character-oriented framing (byte stuffing), how is it transmitted?
In byte stuffing, if an ESC byte occurs inside data, an extra ESC byte is stuffed before it so the receiver interprets the second ESC as data.
In a Stop-and-Wait ARQ protocol, if the transmission delay is 1 ms and propagation delay is 49 ms, what is the maximum achievable channel utilization (efficiency)?
Efficiency eta = Tx / (Tx + 2*Tp) = 1 / (1 + 2*49) = 1 / 100 = 1% = 0.01.
In Stop-and-Wait ARQ, what is the minimum number of distinct sequence numbers required for frames to ensure unambiguous operation?
Stop-and-Wait uses a 1-bit sequence number, giving two distinct sequence numbers, 0 and 1, to distinguish a retransmission from a new frame.