Automatic lightpath service provisioning with an adaptive protected working capacity envelope based on p-cycles

The problem of automatic provisioning of survivable service paths in a transport network in the face of random arrivals and departures, and fundamental traffic uncertainty, is a challenging and interesting problem for research. Essentially to date, only one basic approach is considered, that of provisioning a working path and then explicitly arranging a shared disjoint backup path for protection. This is done on every new connection arrival and is heavily dependent on synchronized network state databases and state dissemination to keep such databases current. The authors described an alternate approach to simplify the process of automatic survivable service provisioning scheme from the end users point of view. Under an adaptive protected working capacity envelope (AP-WCE), statistically stationary but random demand patterns require little or no state dissemination and protected service routing is no different than shortest path working routing. But under non-stationary evolution of the traffic load both spatially and temporally, a slow-acting background process of APWCE reoptimization occurs which keeps the logical configuration of both working envelope and protection overlay always as well matched to the actual traffic load pattern as possible within the finite amount of total as-built transmission capacity. The scheme is attractive as it is easily implemented by existing network control systems and is inherently more scalable to large networks and fast random demands than the current shared-backup scheme because no signaling or state update relating to protection is required on the timescale of individual connection requests. Any such signaling arises only on the timescale of the non-stationary evolution of the traffic load pattern itself.