Question

If a packet is lost in TCP what is the process of resending after it was lost?

Answer 1

In TCP, lost packets are resent using acknowledgements (ACKs) and timeouts. If the sender does not receive an ACK within a set time, it assumes the packet is lost and resends it. The receiver sorts packets by sequence number and confirms receipt with an ACK.

Step-by-step explanation:

When a packet is lost in TCP (Transmission Control Protocol), the protocol's error recovery features are designed to ensure the data is reliably transmitted. TCP provides guaranteed delivery of data between clients and servers by using acknowledgements (ACKs) and timeouts. Here's the process:

1. The sender transmits data packets to the receiver.
2. Each packet is assigned a sequence number, which helps the receiver to identify and rearrange the packets in the correct order.
3. The receiver sends an acknowledgement (ACK) for each packet it receives, indicating the sequence number of the next expected packet.
4. If the sender does not receive an ACK within a certain time frame (determined by the TCP timeout), it assumes that the packet is lost.
5. The sender will then retransmit the lost packet.
6. This process continues until all packets are received and acknowledged by the receiver.

During periods of network congestion, TCP's slow-start, congestion avoidance, and fast retransmit algorithms also work to manage packet flow and prevent future losses.