GATE 2006
October 19, 2023GATE 2003
October 19, 2023Computer-Networks
| Question 50 |
Station A needs to send a message consisting of 9 packets to Station B using a sliding window (window size 3) and go-back-n error control strategy. All packets are ready and immediately available for transmission. If every 5th packet that A transmits gets lost (but no acks from B ever get lost), then what is the number of packets that A will transmit for sending the message to B?
| 12 | |
| 14 | |
| 16 | |
| 18 |
Question 50 Explanation:
Window size is 3, so maximum 3 packets can be remained unacknowledged. In go back ‘n’ if acknowledge for a packet is not received then packets after that packet is also retransmitted.
Frame sequence for 9 frame is shown below. Frame with bold sequence number gets lost.
1 2 3 4 [5 6 7] 5 6 [7 8 9] 7 8 9 9 = 16
Frame sequence for 9 frame is shown below. Frame with bold sequence number gets lost.
1 2 3 4 [5 6 7] 5 6 [7 8 9] 7 8 9 9 = 16
Correct Answer: C
Question 50 Explanation:
Window size is 3, so maximum 3 packets can be remained unacknowledged. In go back ‘n’ if acknowledge for a packet is not received then packets after that packet is also retransmitted.
Frame sequence for 9 frame is shown below. Frame with bold sequence number gets lost.
1 2 3 4 [5 6 7] 5 6 [7 8 9] 7 8 9 9 = 16
Frame sequence for 9 frame is shown below. Frame with bold sequence number gets lost.
1 2 3 4 [5 6 7] 5 6 [7 8 9] 7 8 9 9 = 16