One of the major hurdles limiting IPv6 adoption is the existence of poorly managed experimental IPv6 sites that negatively affect the perceived quality of the IPv6 Internet. To assist network operators in improving IPv6 networks, we are exploring methods to identify wide-area IPv6 network problems. Our approach makes use of parallel IPv4 and IPv6 connectivity to dual-stacked nodes.

We identify the existence of an IPv6 path problem by comparing IPv6 delay measurements to IPv4 delay measurements. Our test results indicate that the majority of IPv6 paths have delay characteristics comparable to those of IPv4, although a small number of paths exhibit a much larger delay with IPv6. Thus, we hope to improve the quality of the IPv6 Internet by identifying the worst set of problems.

Our methodology is simple. We create a list of systems with IPv6 and IPv4 addresses in actual use by monitoring DNS messages. We then measure delay to each address in order to select a few systems per site based on their IPv6:IPv4 response-time ratios. Finally, we run traceroute with Path MTU discovery to the selected systems and then visualize the results for comparative path analysis. This paper presents the tools used to support this study, and the results of our measurements conducted from two locations in Japan and one in Spain.