PERFORMANCE ANALYSIS OF A PACKET ASSEMBLY FUNCTION

Packet assembly functions, in which message elements are accumulated to form a larger message are commonly employed in a variety of computer and communication systems. The underlying rationale for employing such bundling functions is twofold. First of all, by enabling multiple messages to share a fixed overhead, the resources (network bandwidth and CPU real time) can be utilized more efficiently. Second, message bundling can be used as an interface between dumb terminals and more sophisticated networks, such as those employing X.25. In the latter case, the functionality of the message assembly function has been standardized in CCITT recommendation X.3. In this note, we analyze a general packet assembly function in which the bundle is completed whenever any one of a number of conditions is satisfied. These conditions subsume those most commonly found in practice. The analysis yields the distribution of bundle size, and in several useful cases, closed form expressions for the mean bundle size is obtained.