Large Scale Topology Discovery for Public IPv6 Networks

Understanding the topology of large scale IPv6 networks is essential to the procurement of good architectural design decisions, particularly with respect to address allocation and distribution schemes. The former distributed topology discovery applications deploy multiple probing hosts throughout the network. This approach relies on the ability to deploy probing hosts throughout the network, which in many cases is not possible. Source routing support in IPv6 routers is a mandated feature and hence mostly enabled. With respect to simple traceroute, source routing allows one to discover paths between arbitrary pairs of network nodes, but it is such difficult to avoid probing redundancy with a null probing stopping set in the initial phrase of discovery. This paper presents two probing systems: VDPS (Virtual Distributed Probing System) and SRPS (Source Routing Probing System). Firstly, VDPS discovers the BTI (Basic Topology Information) of IPv6 networks. Secondly, SRPS selects seeds from the BTI. In the processing of SRPS, it is very effective in avoiding probing redundancy rely on the probing stopping set initiated by the BTI. Finishing the implementation of SRPS, the coverage of probing is increased greatly. We also present some initial results from probing the CERNET2, currently the largest public IPv6 network of China. The results illustrate the effectiveness of coverage and avoiding probing redundancy.