OPC relies on DCOM, which uses reliable TCP/IP communication. TCP has built-in automated error recovery. So when a network packet is lost, TCP communication ensures the packet is automatically re-sent so there is no communication loss. This error recovery results in periodic brief communication delays, which companies typically overlook. However, eventually, TCP is unable to compensate, which results in a less frequent time out, which most network specialists explain away as something that “just happens.”
DCOM also compensates when TCP times out by automatically resending data. The resulting system typically handles most network disruptions. However, when timeouts are too serious, DCOM and TCP are unable to recover and communication stops. Some applications are able to recover automatically, but they are unable to repair the underlying cause, which is transmission problems and data loss.