The TP protocol makes use of a standard ISO address format, including a Network Service Access Point, and a Transport Service Entity Selector. Subclass 4 may make use of the internet Internet address format.
Active sockets initiate connections to passive sockets.
Once a connection has been established the socket's address is fixed by the peer entity's location. The address assigned the socket is the address associated with the network interface through which packets are being transmitted and received. The ISO Transport Protocol implemented for AOS R2 at the University of Wisconsin - Madison, and modified for inclusion in the Berkeley Software Distribution, includes classes 0 and 4 of the ISO transport protocols as specified in the June 1986 version of IS 8073. Class 0 does not provide the expedited data service. The protocols are implemented as a single transport layer entity that coexists with the Internet protocol suite.