Data Link Layer
Q21.
Consider a 128 \times 10^{3} bits/second satellite communication link with one way propagation delay of 150 milliseconds. Selective retransmission(repeat) protocol is used on this link to send data with a frame size of 1 kilobyte. Neglect the transmission time of acknowledgement. The minimum number of bits required for the sequence number field to achieve 100% utilization is ________.Q22.
For the IEEE802.11 MAC protocol for wireless communication,which of the following statements is/are TRUE? I. At least three non-overlapping channels are available for transmissions. II. The RTS-CTS mechan is misused for collision detection. III. Unicast frames are ACKed.Q23.
In a token ring network the transmission speed is 10^7 bps and the propagation speed is 200 meters/\mu s. The 1-bit delay in this network is equivalent to:Q24.
Consider two hosts X and Y, connected by a single direct link of rate 10^{6} bits/sec . The distance between the two hosts is 10,000 km and the propagation speed along the link is 2x10^{8} m/sec . Host X sends a file of 50,000 bytes as one large message to host Y continuously. Let the transmission and propagation delays be p milliseconds and q milliseconds, respectively . Then the values of p and q areQ25.
A certain population of ALOHA users manages to generate 70 request/sec. If the time is slotted in units of 50 msec, then channel load would beQ27.
A network has a data transmission bandwidth of 20 \times 10^{6} bits per second. It uses CSMA/CD in the MAClayer. The maximum signal propagation time from one node to another node is 40 microseconds. The minimum size of a frame in the network is ______ bytes.Q28.
A sender uses the Stop-and Wait ARQ protocol for reliable transmission of frames. Frames are of size 1000bytes and the transmission rate at the sender is 80Kbps(1Kbps=1000 bits/second). Size of anacknowledgement is 100bytes and the transmission rate at the receiver is 8Kbps. The one-way propagation delay is 100milliseconds. Assuming no frame is lost, the sender throughput is _____bytes/second.Q29.
In CRC if the data unit is 100111001 and the divisor is 1011 then what is dividend at the receiver?Q30.
A link has a transmission speed of 10^{6} bits/sec. It uses data packets of size 1000 bytes each. Assume that the acknowledgment has negligible transmission delay, and that its propagation delay is the same as the data propagation delay. Also assume that the processing delays at nodes are negligible. The efficiency of the stop-and-wait protocol in this setup is exactly 25%. The value of the one-way propagation delay (in milliseconds) is ________.