An experimental evaluation of the total cost of NTP topology

Abstract

To improve the quality of the Internet, the behavior of Internet is evaluated by active or passive measurements. For a one directional measurement method, it is assumed that the network time protocol (NTP) server can maintain the exact absolute time. But the relative time of the NTP server depends on the NTP server-client topology and the interval time of peering hosts. In this research we define the offset time of the peering hosts, propose the evaluation model of the NTP based network and define the total cost of the NTP topology. We measure the offset time between two NTP servers by experiments in various network structures and extract the parameters that cause the offset time drift. From the results of a few experiments, we discovered that (1) a large number of hosts under 100 does not affect the accuracy of NTP server, (2) the processing time of the NTP server depends on synchronous processing, (3) the difference between the sending and receiving packet delay affects the real offset value, (4) if there is no NTP server, there is a 0.028 (millisecond/second) drift, and (5) there are reasons for the offset time drift in peer host synchronization. From these results, we can get some of the characteristics of the NTP evaluation model.