Skewless Network Clock Synchronization

TL;DR

This paper introduces a skewless network clock synchronization algorithm that converges reliably even with timing loops, outperforming existing solutions like NTP and PTP in accuracy and robustness.

Contribution

The paper presents a novel skewless synchronization algorithm that guarantees convergence without offset jitter, even in the presence of timing loops, unlike traditional methods.

Findings

Algorithm converges under timing loops

Outperforms NTPv4 and IBM CCT in experiments

Highly connected networks improve synchronization accuracy

Abstract

This paper examines synchronization of computer clocks connected via a data network and proposes a skewless algorithm to synchronize them. Unlike existing solutions, which either estimate and compensate the frequency difference (skew) among clocks or introduce offset corrections that can generate jitter and possibly even backward jumps, our algorithm achieves synchronization without these problems. We first analyze the convergence property of the algorithm and provide necessary and sufficient conditions on the parameters to guarantee synchronization. We then implement our solution on a cluster of IBM BladeCenter servers running Linux and study its performance. In particular, both analytically and experimentally, we show that our algorithm can converge in the presence of timing loops. This marks a clear contrast with current standards such as NTP and PTP, where timing loops are specifically avoided. Furthermore, timing loops can even be beneficial in our scheme. For example, it is demonstrated that highly connected subnetworks can collectively outperform individual clients when the time source has large jitter. It is also experimentally demonstrated that our algorithm outperforms other well-established software-based solutions such as the NTPv4 and IBM Coordinated Cluster Time (IBM CCT).