In IP networks, path delay between two end-hosts is the key metric for evaluating the network performance. Moreover, delay plays a significant role in several overlay network construction protocols, peer-to-peer (P2P) applications, etc.

A popular example is P2P networks which need to build an overlay between peers in a way that minimizes the message exchange delay among the peers. Besides, the clock error and the location error are the main factors to influence the measurement accuracy in the network path delay measurement.

In this research, a new scheme for accurate path delay measurement is presented. The novel scheme of the network path delay measurement is shown in Figure 1. In the scheme, Khlifi’s clock synchronization algorithm is used to eliminate the clock error between two end-hosts. And a kernel network driver (an intermediate driver based on Windows Network Driver Interface Specification) is utilized to eliminate the location error. In addition, the User Datagram Protocol (UDP) is utilized to carry out the network path delay measurements.

Figure 1. Scheme Overview (Image by CHEN)

In the experiment, to evaluate the performance and accuracy of the measuring probe, a comparison program (named U-Measurer) is designed. Although that is not associated with the accurate timestamp collection driver, it makes the timestamp information in its own process space.

The experimental results show that the new scheme can practically improve the measurement accuracy of network path delay, and make sure the measurement standard deviation to be lowered 10μs under different packet lengths and host loads. Since this scheme does not need any additional software and hardware, it has lower cost and can be applied widely. In this research, Windows XP is used as the target operating system. However, the exploited concepts are general and can also be adapted to other operating systems.

The research was supported by the Important National Science & Technology Specific Projects of China under grant no.2010-ZX03004-002-01, the National Natural Science Foundation of China (11102124, 61102076, and 60939002), the Program for New Century Excellent Talents in University of China (NCET-10-0604), the Youth Foundation of Sichuan Province (09ZQ026-028), and the Ph.D. Programs Foundation of Ministry of Education of China (20090181110053).

The research entitled “Accurate and Low-cost Scheme for Network Path Delay Measurement” has been released online: http://ojs.academypublisher.com/index.php/jsw/article/view/jsw080613981404 and on a state of corrected proof in Journal of Software (Vol. 8, No. 6, June 2013).