Using latency as a QoS indicator for global cloud computing services

Many globally distributed cloud computing (CC) applications and services running over the Internet, between globally dispersed clients and servers, will require certain levels of QoS in order to deliver and give a sufficiently smooth user experience. This would be essential for real-time streaming multimedia applications such as online gaming and watching movies on a pay as you use basis hosted in a CC environment. However, guaranteeing or even predicting QoS in global and diverse networks that are supporting complex hosting of application services is a very challenging issue that needs a stepwise refinement approach to be solved as the technology of CC matures. In this paper, we investigate if latency in terms of simple ping measurements can be used as an indicator for other QoS parameters such as jitter and throughput. The experiments were carried out on a global scale, between servers placed in universities in Denmark, Poland, Brazil, and Malaysia. The results show the correlation between latency and throughput, and between latency and jitter, even though the results are not completely consistent. As a side result, we were able to monitor the changes in QoS parameters during a number of 24-hour periods. This is also a first step toward defining QoS parameters to be included in service level agreements for CC at the global scale in the foreseeable future