Limitation of Performance Enhancement Proxy with specialized oil and gas applications

Although performance enhancement proxy (PEP) has been proven to be an effective solution to address TCP´s performance issues over satellite links, it has some limitations in terms of memory that may be a serious problem in cases where a large number of TCP sessions need to be maintained between endpoints. We experienced one of these cases in Saudi Aramco where drilling Web-based applications were establishing, maintaining, and closing large numbers of TCP sessions. The applications, possibly due to PEP´s failure to hold TCP´s end-to-end semantics, were not terminating sessions in a CLOSE_WAIT state. Further, large numbers of terminated sessions were transitioning to TIME_WAIT states. Both session types were staying active long enough to cause the PEP translation table to reach its limit of 500 concurrent sessions and deny any new TCP connections. To address this issue, modifications to our remote terminal PEPs were required to clear these sessions based on timeouts.