Abstract
Network topology information is useful for network administration and planning. Techniques for automatic generation of the network layer topology maps of IP networks can be found in [2,3,7]. The devices in a subnet can be found using a network layer topology discovery tool. However, the link layer topology of the subnet can not be obtained by a network layer topology discovery tool. An algorithm for automatic discovery of the link layer topology of an IP subnet is proposed in this paper. The algorithm uses the link layer topology configuration information obtained from various sources including the MIBs in routers, bridges, and switches, the Internet Control Message Protocol (ICMP), the Domain Name System (DNS), and etc. to produce the link layer topology map. The proposed link layer topology discovery algorithm has been implemented based on the Tcl/Tk [4,5,6] and Scotty [8] environment.