Circuit switches have simpler data paths and are potentially much faster than packet switches. Taking advantage of this difference makes very high-capacity all-optical circuit switches feasible, whereas all-optical packet switches are a long way from commercial practicality. Peak-allocation, that is eliminating the benefits of statistical multiplexing, is circuit switches' main disadvantage, and what prevents their widespread adoption. However, the rising amount of already abundant link capacity will eliminate this drawback. Our research focuses on how the existing IP infrastructure can incorporate fast, simple (and perhaps optical) circuit switches. Several approaches to this already exist, but we propose a technique called transmission-control protocol (TCP) switching in which each application flow (usually an individual TCP connection) triggers its own end-to-end circuit creation across a circuit-switched core. Based on IP switching, TCP switching incorporates modified circuit switches that use existing IP routing protocols to establish circuits. Routing occurs hop by hop, and circuit maintenance uses soft state, that is, it is removed through an inactivity time-out.
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