Yves Baguette

Comparison of TP4, TCP and XTP Part. 2: Data Transfer Mechanisms

This paper is the second part of a comparative study of the transport mechanisms of three protocols: ISO TP4, XTP and, to a lesser extent, DARPA TCP. Whereas the first partis entirely dedicated to the connection management mechanisms, the mechanisms compared in this second part are those used during the phase of data transmission over a connection. The comparison aims at highlighting the limitations and drawbacks of the data transfer mechanisms of the existing TP4 and TCP protocols as regards their applicability in HSLANs environments characterized by a high bandwidth and a low error rate. It also aims at clearly identifying the area where the emerging XTP contributes to the improvement of the past situation. Like its companion paper, this paper takes account of the last Revision 3.6 of XTP and of the upgraded version of the ISO Transport Protocol which has been circulated for ballot as Draft International Standard (DIS) 8073.

Comparison of TP4, TCP and XTP - Part 1: Connection Management Mechanisms (*)

This paper is the first part of a comparative study of the transport mechanisms of three protocols: ISO TP4, XTP and, to a lesser extent, DARPA TCP. This first part focuses exclu- sively on the connection management (i.e. connection set-up and release) mechanisms. The mechanisms used during the phase of data transfer over a connection will be analysed in the companion paper. The goal of the comparison of the connection management mechanisms is to determine the suitability of each of the three protocols assuming that they operate in HSLANs environments characterized by high performance but also, possibly, by a wide range of applica- tion requirements as regards the types of communication s to provide. This paper takes account of the very last Revision 3.6 of XTP and of the upgraded version of the ISO Transport Protocol which has been circulated for ballot as Draft International Standard (DIS) 8073.

QoS Enhancements and the New Transport Services

The transport protocols TCP and TP4 have been designed in the late seventies at a time when the network environment was essentially based on the switched telephone network and on leased-lines and when the packet switching was an emerging concept.