Closing control loops over networks is becomingincreasingly popular in embedded applications because of itsflexibility, but it also introduces many new problems. From acontrol perspective, the computer system will introduce (possiblyrandom) delays in the control loop. There is also the potentialproblem of lost measurement signals or control signals. Froma real-time perspective, the first problem is figuring out thetemporal constraints (deadlines, etc.) of the different tasks in thesystem, and then scheduling the CPUs and the network such thatall constraints are met during runtime. As a recurring example,a DC servo, whose position control-loop that is closed over aSwitched Ethernet communication network is studied. It is thenextended to three such systems running parallel sharing the CPUtime and the network bandwidth. Hence different schedulingpolicies with subtask scheduling is investigated.