Negative acknowledgment
Negative acknowledgment
Negative acknowledgment (NAK) is a message sent by a receiver to indicate that it has not received a positive acknowledgment (ACK) from the sender, typically due to transmission errors or a problem with the receiver. The sender responds to a NAK by resending the data.
What does Negative acknowledgment mean?
Negative acknowledgment (NAK) is a data transmission control mechanism that indicates that a receiver has not successfully received a message or request and is asking for it to be retransmitted. It is used in a variety of communication protocols, such as TCP, UDP, and CAN, to ensure the reliable delivery of data.
When a receiver sends a NAK, it is typically acknowledging that it has received a message but has detected some type of error or inconsistency in the message. This error could be anything from a missing or corrupted header to an invalid checksum. The receiver will Send a NAK to the sender to indicate that it cannot process the message and that it needs to be retransmitted.
The sender, upon receiving a NAK, will typically retry sending the message. It may do this multiple times Until the receiver successfully acknowledges receipt of the message or until a predefined timeout period is reached.
Applications
Negative acknowledgment is essential in technology today because it ensures the reliable delivery of data in an unreliable network environment. For example, in a TCP connection, NAKs are used to recover from lost or corrupted packets. When a receiver receives a packet that is out of order or has a corrupt checksum, it will send a NAK to the sender. The sender will then retransmit the packet, ensuring that the receiver receives all of the data in the correct order and without errors.
Negative acknowledgment is also used in other applications, such as CAN (Controller Area Network) and USB (Universal Serial Bus). In CAN, NAKs are used to arbitrate bus access when multiple devices are trying to transmit data at the same time. In USB, NAKs are used to signal that a device is not ready to Receive data.
History
The concept of negative acknowledgment dates back to the early days of telegraphy. In 1855, the American inventor Elisha Gray developed a system for Transmitting telegrams that included a mechanism for the receiver to acknowledge receipt of a message. This system used a simple two-wire circuit, with one wire used to transmit data and the other wire used to transmit acknowledgments. If the receiver did not acknowledge receipt of a message, the sender would retransmit the message.
The concept of negative acknowledgment was later adapted for use in data communication networks. In the 1970s, the development of the TCP/IP protocol suite included the use of NAKs as a way to recover from lost or corrupted packets. TCP/IP is the most widely used protocol suite for data communication on the Internet today, and it relies heavily on the use of NAKs to ensure the reliable delivery of data.