The weaknesses of this setup include the following:

• There is DCOM communication between the edge and the OPC server, which means we have to deal with DCOM issues related to configuration, performance, and maintenance.
• Since the edge uses the OPC Classic interface, it can only run on a Windows box.
• For security reasons, the edge and the OPC server must run on different networks that are segregated by means of firewalls. By default, however, DCOM assigns ports dynamically from the TCP port range of 1024 to 65535, and it is not easy to restrict the number of the TCP ports used by DCOM to allow it to cross traffic through the firewalls.