A Credit Manager for Traffic Regulation in High-speed Networks: A Queueing Analysis

In this paper, we examine the behavior of a source subject to flow control by a credit manager. The source receives packets for transmission into a high-speed network according to a renewal process. The credit manager regulates the flow of data into the network by the following method. First, credit is generated at a fixed rate and is allowed to accumulate subject to an upper bound. Second, a packet is allowed to start transmission only if the accumulated credit is at least as large as the service time of the packet. Otherwise, the packet waits until the required amount of credit has been accumulated. Third, the credit bank is depleted at the onset of service by an amount which equals the service time. The main purpose of the credit manager is to smooth out the burstiness of the input process, thereby making it easier for the network to handle large amounts of data without undue delays, congestion, or buffer overflows. Despite the difficulty of this problem, we find the distributions of queue length, sojourn time, and interdeparture time by assuming a special structure for the service-time distribution and the credit bank. We show, by numerical examples, that our algorithms can be used to solve practical problems.