Automatic repeat request error management mechanism is provided by

Automatic Repeat reQuest (ARQ) is an error management mechanism provided by data communication protocols to ensure accurate and reliable transmission of data. When ARQ is implemented in a communication system, the receiver automatically requests the sender to resend data whenever an error is detected in received data packets. This error detection is commonly achieved through mechanisms like checksums or cyclic redundancy checks (CRC).

ARQ includes several schemes, such as Stop-and-Wait ARQ, Go-Back-N ARQ, and Selective Repeat ARQ, each with its method of handling errors and ensuring that data is transmitted correctly and in order.

1. Stop-and-Wait ARQ: In this simplest form, the sender transmits one data packet and waits for an acknowledgment (ACK) from the receiver before sending the next packet. If an error is detected, the receiver sends a negative acknowledgment (NACK), prompting the sender to retransmit the packet. This method is straightforward but can be inefficient, especially over long-delay or high-capacity channels, due to its one-at-a-time packet transmission mode.

2. Go-Back-N ARQ: To improve efficiency, Go-Back-N ARQ allows the sender to transmit multiple packets without waiting for an acknowledgment for each one. The receiver still acknowledges packets, but if an error is detected in a packet, it sends an acknowledgment for the last correctly received packet. The sender then retransmits the erroneous packet and all subsequent packets. This can lead to the retrans