Complete Protocol dictionary, glossary and reference
TP4: ISO Transport Protocol Class 4
Transport Protocol Class 4 (TP4), one of the five transport layer protocols existing in the OSI suite, offers error recovery, performs segmentation and reassembly, and supplies multiplexing and demultiplexing of data streams over a single virtual circuit. TP4 sequences PDUs and retransmits them or re-initiates the connection if an excessive number are unacknowledged. TP4 provides reliable transport service and functions with either connection-oriented or connectionless network service. TP4 is the most commonly used of all the OSI transport protocols, which is similar to the Transmission Control Protocol (TCP) in the TCP/IP suite.
ISO Document 8073