Question

A window holds bytes 2001 to 5000. The next byte to be sent is 3001. Draw a figure

to show the situation of the window after the following two events.
a. An ACK segment with the acknowledgment number 2500 and window size
advertisement 4000 is received.
b. A segment carrying 1,000 bytes is sent.

Answer 1

Summarizing the events in the sliding window protocol and visualized in the provided illustration:

1. **Initial State**:

• Window holds bytes 2001 to 5000.
• The next byte to be sent is 3001.

2. **After Receiving ACK Segment**:

• An ACK segment with acknowledgement number 2500 is received.
• Window size advertisement of 4000 is also received.
• The window adjusts to hold bytes 2500 to 6499.

3. **After Sending 1000 Bytes**:

• A segment carrying 1000 bytes from 3001 to 4000 is sent.
• The next byte to be sent is now 4001.

The illustration provided visualizes this progression, showing the initial window, the adjustment after the ACK segment, and the final state after sending 1000 bytes. This demonstrates the dynamic nature of the sliding window protocol in efficiently managing data transmission in a network.

To illustrate this scenario, let's break down the steps and then draw a figure to represent the sliding window in a computer network:

1. Initial State:

• The window holds bytes 2001 to 5000.
• The next byte to be sent is 3001.

2. After Receiving ACK Segment:

• An ACK (Acknowledgement) segment with the acknowledgement number 2500 and a window size advertisement of 4000 is received.
• This means that all bytes up to 2499 have been acknowledged.
• Since the window size is advertised as 4000, the new window can hold bytes from 2500 to 6499.

3. After Sending 1000 Bytes:

• A segment carrying 1000 bytes is sent, starting from byte 3001.
• This means bytes 3001 to 4000 are sent.
• The next byte to be sent is now 4001.

Now, let's visualize this in a figure. The figure will show a linear representation of the bytes, indicating the initial window position, the effect of the ACK segment, and the state after sending 1000 bytes.

(IMAGE IS GIVEN BELOW)

Here is the illustration showing the sliding window protocol in a computer network as described:

• The initial window holds bytes 2001 to 5000, with the next byte to be sent being 3001.
• After receiving the ACK segment with the acknowledgement number 2500 and a window size advertisement of 4000, the window adjusts to hold bytes 2500 to 6499.
• Finally, after sending 1000 bytes from 3001 to 4000, the new window position is shown with the next byte to be sent being 4001.

The linear representation, along with arrows and labels, clarifies the changes in the window position after each event.

The complete question is here:

A window holds bytes 2001 to 5000. The next byte to be sent is 3001. Draw a figure to show the situation of the sliding window after the following two events:

a. An ACK segment with the acknowledgement number

2500 and window size advertisement 4000 is received.

b. A segment carrying 1000 bytes is sent.

Answer 2

The sliding window protocol is used to control data flow in networking, where the window represents the range of allowable unacknowledged bytes to be sent. Receiving an ACK for byte 2500 does not shift the window as the sender is already at byte 3001. So the correct answer is option A.

Step-by-step explanation:

The situation you're describing is in the context of a sliding window protocol used in network data transmission, likely in the TCP/IP model. The window you are referring to is the portion of the data stream that the sender is allowed to send before waiting for an acknowledgment (ACK).

After receiving the ACK segment with the acknowledgment number 2500 and a window size advertisement of 4000, the window's starting point should be updated. However, since the next byte to be sent is 3001, this ACK for byte 2500 does not move the window because 3001 is already ahead of the acknowledged byte. Therefore, the window remains at bytes 2001 to 5000.

When a segment carrying 1,000 bytes is sent, the starting edge of the window will progress forward by 1,000 bytes. Assuming no other acknowledgments have been received to move the window further, the new window would hold bytes 3001 to 6000 (assuming cumulative acknowledgment and without considering individual acknowledgment for each segment).