Comparison of UPC mechanisms in a DQDB/B-ISDN gateway

摘要

In B-ISDN, a policing function such as usage parameter control (UPC) is mandatory to constraint the cell flow of a new connection to respect its contract. The case of a user accessing B-ISDN via a DQDB metropolitan area network (MAN) is considered. One assumes that this user generates a variable bit rate (VBR) traffic towards the user network interface (UNI). We investigate the influence of the internal DQDB traffic on the time structure of this VBR cell flow when it enters the DQDB/B-ISDN gateway. We then consider two UPC functions which are the leaky bucket and the spacer-controller to police the VBR connection. The efficiency of each of these two UPC mechanisms is evaluated in terms of the cell delay variation and dynamics. The influence of several source parameters such as the mean bit rate, the peak bit rate and the burstiness on UPC efficiency is investigated.