Question 1
1)
2)
3)
4)
5)
6)
A1 = 5, ack = null
B1 = 20, ack = 5
A2 = 35, ack = 21
B2 = 40, ack = 36
A3 = 65, ack = 41
B3 = 60, ack = 66
Question 2
a) Not enough information to determine
b) It’s GBN with a window size of 4 and a minimum wait duration after the window to
avoid unnecessary re-transmissions before receiving the ACK for packet 0
Question 3
Question 4
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Even if the round-trip time (RTT) is known, a timeout timer is still necessary in a reliable
data transmission protocol, as it detects and recovers from packet loss caused by various
factors. It also provides additional benefits like detecting and recovering from network
congestion and duplicate packets
In conclusion, a timeout timer is still necessary in an rdt protocol, even if the RTT is
known between a sender and a receiver. Although a known RTT can help adjust the
timeout timer appropriately, it cannot prevent packet loss due to other factors such as
hardware failure or network outage. Moreover, the use of a timeout timer provides
additional benefits such as detecting and recovering from network congestion and
duplicate packets.
Question 5
● Bytes from 100 to 399 have been received.
● Bytes from 400 to 599 have been received.
● Bytes from 600 to 999 have been received.
The next sequence number that Host A will send would be 1000, because it follows the
pattern of incrementing by 100 for each segment.
Since Host A will send the next sequence starting from 1000, the next ACK number sent by B
will be 1000, indicating that it is ready to receive bytes with a sequence number of 1000.
Question 6
We need 2 iterations.