What are ports 0xfffffe (Fabric Port) and 0xfffffc (Directory Server) as seen in systool -c fc_remote_ports output?

Issue

• The systool command outputs the roles for fibre channel ports, what do the different roles mean?
• What are the "well known" port ids associated within SAN fabrics and what do they represent/do?
• What are these "Fabric Port" and "Directory Server" SAN devices?
• I can't find the port with id 0xFFFFFC on our san, but its listed in systool ...