In the integrated service networks, the real-time traffic and the non-real-time traffic share the network resources so that one can affect the quality of another and vice versa. In this context, it is very crucial to develop some mechanism to guarantee the quality-of-service (QoS) required by the real-time traffic. In this paper, we analyze the delay time of CBR packets from real-time sources when CBR packets have the priority over UBR packets in a manner that UBR packets are serviced only if no CBR packets are waiting in the buffer. There are two types of CBR packets; i.e., they are different in their transmission rate and/or packet length. In this sense, the case treated is called the heterogeneous case. We obtain various numerical results on the statistical bound on delay time such as the 99.9-percentile delay and compare it with the deterministic bound. By the comparison, we show that call admission control (CAC) based upon the statistical bound is very effective in using the network resources efficiently when CBR packets can tolerate some loss due to late arrival. We also examine whether the delay time distribution in the heterogeneous case can be approximated by that of some homogeneous cases.
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