The Future of SCPS as an Acceleration Solution

The Department of Defense (DoD) is in the process of implementing widespread usage of IP Modems on its global network and planning to standardize them. The Defense Information Systems Agency (DISA) has recently published a Joint IP Modem Specification (JIPM) that defines future standards for IP modems for the entire armed forces. Included in this specification is an option for a Performance Enhancing Proxy (PEP) embedded within the modem that adheres to a communication standard published in 2005 called the Interoperable PEP (I-PEP) proposed by the Satlabs group, a European conglomerate. I-PEP builds on top of TCP, SCPS-TP, and recent TCP extensions while maintaining backward compatibility with TCP and SCPS-TP. With the introduction of a newer, optimized, open standard, it is unclear if SCPS-TP will remain the de facto standard. SCPS has been used successfully for several years in fixed bandwidth environments, but is still proving it can work successfully in all dynamic bandwidth environments that use IP modems. The direction that the MILSATCOM community is heading in regards to dynamic bandwidth environments, coupled with SCPS-TP's questionable performance metrics in those environments, brings the future of the SCPS protocol into question. Building and maintaining an open protocol benefits the military community by fostering competition from multiple vendors while still allowing for interoperability and not sacrificing performance. This paper examines a few possible alternatives to the SCPS standard given the current environment.