1. A method of network topology determination for at least one Control & Instrumentation (C&I) system in an industrial facility (IF), comprising: discovering a network type, and all nodes and interconnecting networking devices including switches in said IF C&I system, said IF C&I system comprising a first C&I system and a second C&I system, using at least one data agent in a data agent block and said at least one data agent comprises a first data agent and a second data agent, said first data agent compatible with a first operating system (OS) in said first C&I system, and said second data agent is compatible with a second OS used in said second C&I system that is different from said first OS; collecting additional connectivity information including a connection of said nodes to a specific port; determining network relationships of said nodes and said interconnecting networking devices in said IF C&I system, by obtaining port to Media Access Control (MAC) address mapping data from a MAC table stored at said switches and Address Resolution Protocol (ARP) data from an ARP table stored at a server in said IF C&I system; determining at least one of node type and node address that including which node of which type with what IP address is connected to which port of which switch present in the network, for a network topology diagram; and generating the network topology diagram of said IF C&I system from said nodes and said interconnecting networking devices, said additional connectivity information, and said network relationships, wherein said discovering, said collecting, said determining, and said generating are all automatically implemented.