DATA COMMUNICATION PRINCIPLES Framework for Studying a Protocol

DATA COMMUNICATION PRINCIPLES : Framework for Studying a Protocol

Framework for Studying a Protocol Before closing this chapter, let’s look at the possibility of a common framework in which we can project all or at least most protocols. If we are successful, we can structure the study of protocols by simply fitting it in the framework. Here is one possible approach. All protocols provide some substantial service that determines its equivalence to one or more OSI layers. So, the very first thing we look for could be where a certain protocol (or suite of protocols) fits in relation to the OSI-RM. Alternatively, if we have that knowledge, it gives us a hint as to what should be our expectations. For examples, if a protocol provides logical functions for data exchanged between two directly connected stations; we know that it is a DLC protocol. Alternatively, if we know that a protocol is a DLC protocol, we know what type of functions to expect from it. Secondly, each protocol performs a set of functions. Each function may be performed by a (set of) procedure(s).

Therefore, the second thing that we may want to look in the study of a protocol is what functions it provides and how. Usually, these functions are obvious from the protocol header/trailer. The procedure in order to implement each of these functions is also important to know. For example, there are several ways of providing a flow control mechanism. If it is known that a protocol provides flow control, this is not enough information in fully understanding the protocol. The third and important characteristic of any protocol is its performance. Given the layer information and set of functions that it can perform, how well does it actually perform these functions? This is perhaps the most important part of protocol study, and sometime most neglected. It must be noted that many developments in protocols and new standards are required just because of this reason – the existing ones can’t perform as well. However, the performance study of a protocol is admittedly a complex subject and should be studied at a higher level.

In summary, the following knowledge can help one fully understand even design of a protocol. Its level in the OSI network architecture in order to understand the main functions of the protocol. Functions and procedures provided by the protocol. Performance bottlenecks and efficient implementations.

REFERENCES • Ahmad A. - Data Communication Principles. For Fixed and Wireless Networks • Cornelius T. Leondes - Database and Data Communication Network Systems, Three-Volume Set_. . -Academic Press