A Queuing Model for a Hybrid Data Multiplexer

We analyze the performance of a buffer that is used to multiplex two types of data. Sporadic short bursts of data, like inquiries from terminals, share the same communication channel with relatively steady streams of data like digitized voice, lengthy messages from computers, data bases, or traffic from a busy trunk. A line-switched network, one that provides a dedicated channel for each connection, is preferred for lengthy steady messages. A packet-switched network, on the other hand, is efficient for messages that are short and bursty. In a packet-switched network, messages are forwarded from node to node in the form of packets of data that include addressing information. In such a network, there is no necessity for a dedicated channel for each connection. 279 A data network could accommodate both types of traffic by dividing the transmission facilities into two fixed parts--one part exclusively for line-switched traffic, the other for packet-switched traffic. The subframe switching concept introduced in Ref. 1 is an example of a temporal division of capacity. The model developed here can be used for the analysis of such a system. In any system where a resource such as a transmission line is shared between two or more types of users, the performance guaranteed to each individual type of customers has to be met. Packet delay and the probability of losing packets are the two measures of performance we consider. Kummerle 2 proposed a model for multiplexing line and packetswitched data and derived, using an ad-hoc approximation, formulas relating the performance measures to the traffic intensity and transmission capacity.