TPOT: translucent proxying of TCP

Transparent proxies are being widely deployed in the current Internet to en able a vast variety of applications. These include Web proxy caching, trans coding, service differentiation and load balancing. To ensure that all IP p ackets of an intercepted TCP connection are seen by the intercepting transp arent proxy, they must sit at focal points in the network. Translucent prox ying of TCP (TPOT) overcomes this limitation by using TCP-OPTIONs and IP tu nneling to ensure that all IP packets belonging to a TCP connection will tr averse the proxy that intercepted the first packet. This guarantee allows t he ad hoc deployment of TPOT proxies anywhere within the network. No extra signaling support is required. In addition to the advantages TPOT proxies o ffer at the application level, they also generally improve the throughput o f intercepted TCP connections. In this paper we discuss the TPOT protocol, explain how it enables various applications, address deployment and scalabi lity issues, and summarize the impact of TPOT on TCP performance. (C) 2001 Elsevier Science B.V. All rights reserved.