Special Protection Systems' requirements define the communications scheme so that the power system protections inside work. An Internet-based communications architecture with two level hierarchy is presented. The upper level is a broadband SDH/SONET network, and the lower network is an IEC61850 standard based Ethernet. The protocols required in each of the layers are determined. The SPS traffic and background traffic of the communication system are also displayed. Finally, a simulation of a hypothetical network based on the Colombian power system is performed, and the network's performance and the transport protocols are evaluated as a function of the delays and dropped packets inside the protocols.