IT 210 computer network

Learning Outcome(s):

Clear understanding of network protocols including Transport Control Protocol / Internet Protocol

2 Marks

Question One

Stop-and-Wait Protocol

Go-Back-N Protocol.

Selective-Repeat Protocol.

Above are the Protocols for Transport Layer. In the table below, please explain how the above protocols work in terms of:

Window size of Sender and Receiver, and how the protocols actually work

Is there going to be out of order packets? If yes, how will they be handled?

Timer.

What does an Acknowledgment number (ackNo) announce? Mention an example.

	Stop-and-Wait	Go-Back-N	Selective-Repeat
Window size of Sender and Receiver / How does it work			The size of the sender and receiver window can be at most one-half of 2m?1 The protocol allows the sender to send as many packets as the size of the receive window.
Out of order packets	There is no out of order packet. So no handling method is needed
Timer	The sender send a packet and start a timer If the timer expires and no ACK received, the sender resends the previous packet.
Acknowledgment Number (ackNo)	The ackNo announces the sequence number of the next packet expected, in modulo-2 arithmetic, Example: If packet 0 has arrived safe and sound, the receiver sends an ACK with acknowledgment 1 (meaning packet 1 is expected next). If packet 1 has arrived safe and sound, the receiver sends an ACK with acknowledgment 0 (meaning packet 0 is expected).

Acknowledgment Number

(ackNo)

The ackNo announces the sequence number of the next packet expected, in modulo-2 arithmetic,

Example:

If packet 0 has arrived safe and sound, the receiver sends an ACK with acknowledgment 1 (meaning packet 1 is expected next). If packet 1 has arrived safe and sound, the receiver sends an ACK with acknowledgment 0 (meaning packet 0 is expected).