Why we need error control at the transport layer?
Thereof, what is error control in transport layer?
Error Control is the issue that occurs at data link layer and transport level as well. Error Control is a mechanism for detecting and correcting the error occurred in frames that are delivered from sender to the receiver. The error occurred in the frame may be a single bit error or burst error.
One may also ask, why do we need both link level and end end reliability? 3 Answers. End-to-end is required because not ALL network layers are particularly reliable, and only the end systems know how much reliability is really required. A link-layer reliability is often used for links that are prone to high error rates such as wireless etc.
Also asked, why do we need another checking mechanism at the transport layer?
The errors between the nodes can be detected by the data link layer control, but the error at the node (between input port and output port) of the node cannot be detected by the data link layer. Many features of the transport layer (e.g. flow control and reliable delivery) are also handled by the data link layer.
Why error correction is more important at the transport layer than at the data link layer?
The error control in the data link layer, works at the packet or stream level, while the error control in the transport layer, works at the message level. The data link layer is not concerned with ordering of packets, while the transport layer is.