Chapter 12, Problem 14E

a.

Explanation of Solution

Given data:

Size of file = 10 KB

We know that:

1 KB = 1024 Bytes

Therefore, 10 KB = 10 × 1024 = 10240 Bytes

Payload size = 100 Bytes

Window size = 2000 Bytes = 20 data packets (100 Bytes = 1 Data packet)

Number of acknowledgements received by sender = 900

To find: Byte that is send next.

Solution:

Finding next byte to send:

Unacknowledged data packets = 19

Number of acknowledgements received by sender = 900

Payload size = 100 Bytes

The next byte is determined by adding the number of acknowledgements received by sender and the payload size that is added with the unacknowledged data packets.

$\begin{array}{c}Nextbyte=acknowledgementsreceived\end{array}$

b.

Explanation of Solution

Given data:

Size of file = 10 KB

We know that:

1 KB = 1024 Bytes

Therefore, 10 KB = 10 × 1024 = 10240 Bytes

Payload size = 100 Bytes

Window size = 2000 Bytes = 19 data packets

Number of acknowledgements received by sender = 900

To find: Last Byte

Solution:

Finding the last byte that is sent without an acknowledgement:

Data packets = 20

Number of acknowledgements received by sender = 900

Payload size = 100 Bytes

The last byte is determined by adding the number of acknowledgements received by sender and the payload size that is added with the data packets that is finally subtracted by 1. The value “1” is subtracted in order to get the last byte of the previous data packet.

$\begin{array}{c}Lastbyte=acknowledgements\text{}received\end{array}$