Compare GO BACK N-ARQ and Selective Repeat Protocol

Go-Back-N ARQ and Selective Repeat Protocol are two fundamental methods used in networking to deal with packet loss and errors. They are both Automatic Repeat Request (ARQ) protocols, but they handle errors differently.

1. Error Handling:

   • Go-Back-N ARQ: In this protocol, if a single packet is found to be in error or lost, all the packets sent after that packet are retransmitted, even if they were received without error. This is because it assumes that the packets are lost in a sequence.
   • Selective Repeat Protocol: In this protocol, only the specific packet that was lost or received in error is retransmitted. This can lead to better efficiency as it avoids unnecessary retransmissions.

2. Buffering:

   • Go-Back-N ARQ: The receiver does not need to maintain a large buffer. It only needs to keep the next expected packet. If packets arrive out of order, they are discarded.
   • Selective Repeat Protocol: The receiver needs to maintain a buffer large enough to store out-of-order packets. This is because it can accept and store packets that arrive out of order.

3. Complexity:

   • Go-Back-N ARQ: This protocol is simpler to implement because it only needs to keep track of the last acknowledged packet and the window size.
   • Selective Repeat Protocol: This protocol is more complex to implement because it needs to keep track of all packets that have been sent but not yet acknowledged.

4. Efficiency:

   • Go-Back-N ARQ: This protocol can be less efficient because it may retransmit packets unnecessarily.
   • Selective Repeat Protocol: This protocol can be more efficient because it only retransmits the packets that were lost or received in error.

5. Throughput:

   • Go-Back-N ARQ: The throughput can be less because of the unnecessary retransmissions.
   • Selective Repeat Protocol: The throughput can be higher because it avoids unnecessary retransmissions.

In conclusion, while Go-Back-N ARQ is simpler to implement, Selective Repeat Protocol can provide better efficiency and throughput. However, it requires more complex management and larger buffer space. The choice between the two would depend on the specific requirements of the network.