TCP uses a checksum on the data it sends to detect any errors that can occur due to the lower layers as lower layers do not provide any specific error detection. TCPMPL uses some primitive error detection over TCP. It sends the sender's id number and the destination's id number in the message header. When messages are received by TCPMPL at the destination, TCPMPL checks whether the destination's id in the message header matches with its id. It also checks whether the sender's id number matches with the source process id number associated with the communication channel.