Transport Layer supports reliable communication
Reliability means ensuring that each piece of data that the source sends arrives at the destination.
Three basic operations of reliability are:
– tracking transmitted data
– acknowledging received data
– retransmitting any unacknowledged data
These reliability processes place additional overhead on the network resources due to the acknowledgement, tracking, and retransmission.
To support these reliability operations, more control data is exchanged between the sending and receiving hosts.