Abstract: Systems and methods are described for restoring wavelength services in mesh networks using pre-configured, standby lightpaths. The standby lightpaths are pre-cross-connected lightpaths that provide connectivity between switching nodes having a fiber link of degree-2 or higher. The restoration method overcomes the problem of optical impairments for long haul connections, avoids wavelength power balancing delays, provides wavelength conversion for capacity efficiency, and allows sharing of links across nonsimultaneous failures.

Abstract: Systems and methods are described for restoring IP traffic flows routed in an IP network in less than 100 ms after the IP network sustains a network failure. The systems and methods are a two-phase fast reroute that uses distributed optimized traffic engineering during backup tunnel restoration and end-to-end tunnel restoration that maximizes sharing among all independent failure scenarios and minimizes the total capacity, total cost, or a linear combination of the two. For defined failure condition scenarios, restoration traffic is routed using pre-computed backup tunnels using a constrained shortest path first method where link weights along the path are chosen dynamically and depend on available and total capacity of the link, latency, and other cost measures such as IP port costs. During the capacity allocation phase, the method reuses capacity already allocated for other independent failure scenarios as much as possible but also adds capacity, if necessary.

Abstract: An arrangement where connections between a terminal and a switch are effected through a serial connection of shared, overloadable, resources, and where conventionally each of the resources has a given number of communication channels, provides for effective congestion control by converting one or more of the communications channels to one or more groups of enhanced signaling channels. The congestion control is effected by employing the enhanced signaling channels, which can carry audible signals, to determine whether to set up requested calls, based on a preselected congestion control process.

Abstract: A method for alleviating congestion problems in prior art networks delays provision of dial tone signals to terminals that are, likely, carrying out a re-dial attempt in excess of a preselected number of re-dial attempts. A determination that the terminal seeking to establish a connection is likely carrying out a re-dial attempt may be based on numerous factors, such as the time since the last time the terminal desired to establish a call, the duration of the last call, etc. The delay that is imposed is, advantageously, sensitive to the number of times the terminal has attempted a re-dial, and on other conditions, such as the cause of the failure to establish a connection, network congestion conditions, etc. In imposing the dial tone delay, identities of the terminals that are to receive a delayed dial tone are placed in a FIFO queue.

Abstract: A method that alleviates congestion problems in prior art networks by insuring that selected classes of calls have a reserved capacity, thus insuring a capability to service at least the selected level of traffic. In an illustrated embodiment, a selected capacity is reserved for voice calls, in contrast to data calls. When a connection request is made and there is unoccupied capacity, a voice call is always serviced, but a data call is serviced only if the number of established data connections is less than capacity of the path required for establishing a connection for the request, minus the capacity reserved for voice call.