Topology discovery in PROFINET

PROFINET, an automation network based on Ethernet, includes the automatic discovery of the physical topology with the link layer discovery protocol (LLDP) in its newest specifications. In this paper we present the objectives of LLDP in PROFINET and general information about the protocol and other parts of IEEE 802.1AB, which describes LLDP. During the analysis of different implementations on the market, we found several problems of LLDP as well as issues with the interaction to a network management system. These are described in the later chapters.