Topology Discovery for Coexisting IPv6 and IPv4 Networks

Having an accurate network topology is vital for newtork performance optimization, configuration control, and fault monitoring .. etc. In this paper, two network layer topology discovery algorithms for IPv6-only and IPv4-only networks, a data link layer topology discovery algorithm, and a transition detection algorithm of coexisting networks are presented. The network layer topology is constructed using the routing information from ip6RouteTable and ipRouteTable, while the data-link layer map is built using data from atTable and dot1dTpFdbTable. The transition detection is carried out by collecting and analyzing all IP addresses of both IP versions, through making the use of multicasting Inverse IPv6 Neighbor Discovery messages and broadcasting IPv4 RARP messages. It is useful for finding out which transition mechanism is deployed in a coexisting network. Consequently, overlapped routers and hosts can be determined to complete the IP network topology discovery.