The key focus of our work is to analyse some jitter control algorithms. We study a jitter control algorithm proposed by Mansour et. al  for networks with guaranteed quality of service (QoS) from a competitive analysis point of view. The authors have analysed the proposed algorithm (on-line algorithm) and also compared its performance to the off-line algorithm. In this paper, the analysis of the on-line algorithm has been dealt with rigorously and relevant conditions have been derived. For delay jitter, we show that the on-line algorithm guarantees the same delay jitter as the off-line algorithm. Also, both the algorithms in their original forms are applicable only to a fixed number of packets. We extend the results to a more practical model in which we compare the off-line algorithm with n packets and the on-line algorithm with n 1 (n 1 > n) packets, arrival times for both the stream of packets being realised from the same statistical model. In this case, we show that there exists a expression for the ratio of buffer size needed in the off-line algorithm to the buffer size needed in the on-line algorithm, provided that the delay jitter in both the cases are equal. © 2011 IEEE.