Timer management in X.25 layer 2-an interpretation

The X.25 layer 2 protocol describes three timers for error recovery and efficient data transfer. Timer management in any protocol requires heavy processing and can cause excessive overheads if not implemented intelligently. This paper discusses some techniques to be followed to reduce these overheads. The number of timers running at any instant, and the number of times that timers need to be set or reset, can be controlled. The piggyback timer, if used intelligently, can lead to efficient data transfers. The current research done in this area assumes Poisson and deterministic traffic types to decide the timer value. Our study of the layer 2 protocol in relation to the higher layers revealed that the traffic pattern can be predicted in some cases. A piggyback scheme was devised that is dependent on the traffic pattern to ensure high performance of the protocol. This scheme is discussed in detail.<>