The smart grid promises a more efficient way of supplying and consuming energy. In essence, the smart grid is a data communications network integrated with the power grid that enables power grid operators to collect and analyze data about power generation, transmission, distribution, and consumption—all in near real time. Smart grid communication technology provides predictive information and recommendations to utilities, their suppliers, and their customers on how best to manage power. To achieve this vision of ubiquitous near–real time information, a transformation of the power grid communications infrastructure is needed, particularly in transmission and distribution substations. While modern data communication has evolved from telephony modems to IP networks, many power utilities are still deploying modem access and serial bus technology to communicate with their substations. The existing supervisory control and data acquisition (SCADA) remote terminal unit (RTU) systems located inside the substation cannot scale and evolve to support nextgeneration intelligence. Since flexible IEC 61850–compliant intelligent electronic devices (IEDs) and utility-grade rugged IP routers and Ethernet switches have become more widely available, many utilities are now ready to transform their communications networks from serial to IP-based communications.