It has been argued that per-flow scheduling is required to provide protection and service differentiation in networks that carry bursty flows. However, the utility of per-flow scheduling algorithms, such as fair queuing, has been questioned when all the flows are shaped to Constant Bit Rate (CBR) at the sources or at the edge of the network. In this paper, we study the effect of using FIFO or fair queuing on the end-to-end performance of CBR traffic in the context of large-scale networks, in which: (1) the bandwidth requirement and the packet sizes vary considerably across the CBR flows; (2) the class of CBR flows occupy different fractions of the total link bandwidth; and (3) the class of CBR flows share each network link with several other flows with different packet arrival patterns. We evaluate the performance of CBR flows in terms of the end-to-end packet delay and jitter. Our results provide an empirical basis to evaluate the effectiveness of FIFO and per flow scheduling for CBR flows, as well as guidelines for deploying CBR services in the Internet.

Representative Publication:

1. J. Sahni, P. Goyal, and H.M. Vin, Scheduling CBR Flows: FIFO or Fair Queuing? In Proceedings of 9th International Workshop on Network and Operating Systems Support for Digital Audio and Video (NOSSDAV99), pp. 13-27, June 1999 [ Abstract | Paper ]