Transport services and protocols for OSI

A Transport Layer has been defined as Level 4 of the open systems Interconnection (OSI) Basic Reference Model. Its major characteristic is that it forms the boundary between data COmmUnication functions (the three Lower layers of the Model) and data processing functions (Levels 5 through 7). The International organization for standardization (ISO) is currently defining a standard Transport service and Protocol for this Layer. Although both technical and political problems are presently hindering the achievement of this objective, it is clear that a fira and generally accepted international standard in tnis area is urgently needed by users and manufacturers. This paper presents rationale and justifications for the proposals under discussion, attempts to clarify the motivations for the differing view and suggests how they could be recondidded application of a realistic and engineered approach to the problems.