|  | 8.5 | The Transport Layer
| 8.5.1 | The distinction between connectionless and connection-orientated transport
Connectionless communication is a fast way to send information to a destination; however, it is not reliable because there is no notification of receipt to the source location. Connectionless protocols include IP and IPX (layer 3) and UDP (layer 4). Connection-oriented protocols include TCP (layer 4) and SPX. Connection-oriented protocols, such as TCP, typically use an acknowledgement (ACK) process between source and destination. If a source does not receive an ACK from the destination, TCP will retransmit the segment until an ACK is received. The processes of segmentation, handshaking/acknowledgement, flow control, and error checking are used to provide reliable transport.