A tiered communications architecture for managing network traffic in a distributed system (100). Communication between client or control computers and a plurality of hardware devices is administered by agent and monitor devices whose activities are coordinated to reduce the number of open channels or sockets. The communications architecture also improves the transparency and scalability of the distributed system by reducing network mapping dependence. The architecture is desirably implemented in a proton beam therapy system (115) to provide flexible security policies which improve patient safety and facilitate system maintenance and development.