A computer running Microsoft Message Queue (MSMQ) Server that functions as a primary site controller (PSC) for one site and contains information about the enterprise configuration and the certification keys in its MSMQ Information Store (MQIS) database. The primary enterprise controller (PEC) also functions as an MSMQ Routing Server.
Administrators can install only one PEC on an MSMQ network. You must install the PEC before you install any primary site controllers.