ABSTRACT
The most common classification of networks for data, voice, and graphic communications are local area networks (LAN), wide area networks, and metropolitan area networks. LANs became very popular for two main reasons: data sharing and resource sharing. The condition for coexistence of computerized systems on the same network assumes they all have network-compatible communications protocols. Network protocols — proprietary, open, and standard — are utilized for interfacing computerized systems connected to the network. Gateways provide translation of different protocols or heterogeneous networks, allowing interoperability of otherwise incompatible systems and networks. The Internet protocol provides so-called connectionless mode of data transfer over the network. Since the area of network protocols is remote from facilities controls and automation and is usually managed by network professionals, readers should always consult their network management whenever contemplating networking of automation systems over common facilities networks. A significant number of facilities utilize Ethernet protocol for their LANs.
