The Xpress transfer protocol (XTP)—a tutorial

XTP is a reliable, real-time, lightweight transfer s layer protocol being developed by a group of researchers and developers coordinated by Protocol Engines Incorporated (PEI) . [ 1,2,31 Current transport layer protocols such as DoD's Transmission Control Protocol (TCP) 141 and ISO's Transport Protocol (TP) 151 were not designed for th e next generation of high speed, interconnected reliable networks such as FDDI and the gigabit/second wide are a networks . Unlike all previous transport layer protocols, XTP is being designed to be implemented in hardware a s a VLSI chip set . By streamlining the protocol, combining the transport and network layers and utilizing th e increased speed and parallelization possible with a VLSI implementation, XTP will be able to provide the endto-end data transmission rates demanded in high speed networks without compromising reliability an d functionality. This paper describes the operation of the XTP protocol and in particular, its error, flow and rate control, inter-networking addressing mechanisms and multicast support features, as defined in the XTP Protoco l Definition Revision 3 .4 . 11 1