An empirical evaluation of landmark placement on Internet coordinate schemes

Many applications can benefit from knowledge of latency between hosts. Recently, there have been proposals such as global network positioning (GNP) (T. S. E. Ng et al., 2002) and Internet coordinate system (ICS) (H. Lim et al., 2003) that attempt to provide this for hosts on the Internet. The schemes work by using a small set of nodes called "landmarks" to compute the coordinates of other hosts. We investigate the effect of placement of landmarks on the performance of these proposals. We show that with random placement, the estimation error of these schemes varies widely. We propose heuristics for placing landmarks that show good performance. We also investigate the behaviour of these schemes with measurement errors and show that GNP is less affected by measurement errors than ICS.