Alcatel-lucent USA Inc.

Alcatel Lucent

Agere Systems Inc.

Lucent Technologies Inc.

Zbigniew M Dziong

Yung-Terng Wang

Muhammad A Qureshi

Ramesh Nagarajan

Bharat Tarachand Doshi

Matthew Tota

Martin S Dell

Wei Li

Ajay Sathyanath

Yu-Kuen Ouyang

A method for determining a restoration path for a new service in a mesh network involves selecting between candidate restoration paths corresponding to a primary path for the new service based on the shared-risk link groups (SRLGs) associated with links in the primary path. The method includes, for each of a plurality of candidate restoration paths associated with the primary path, (1) determining whether the primary path requires any additional restoration bandwidth to be reserved on any link of the restoration path based on whether, for each link of the restoration path, the primary path is SRLG-disjoint from each other primary path that is protected by that link, (2) generating a path cost for the restoration path, where the path cost is a function of whether any additional restoration bandwidth is required; and (3) selecting the restoration path for the new service based on the path cost.

Restoration path calculation considering shared-risk link groups in mesh networks

A method for representing, in a network data structure, a minimum amount of protection bandwidth required to be reserved on each link in a mesh network, to restore service upon failure of another node or link in the network. The method includes (1) receiving a request for a new service in the network, wherein the new service is represented by a service data structure having an identification of each link and transit node in a primary path for the new service, (2) determining, using the network and service data structures, whether the new service requires additional protection bandwidth to be reserved on any link in the network, and (3) updating the network data structure if any additional protection bandwidth is determined to be needed. In one implementation the network and service data structures are vectors and the steps of determining and updating involve vector operations between these structures.

Calculation, representation, and maintenance of sharing information in mesh networks

A protected communication network utilizes a link-based recovery strategy that supports independent recovery paths for individual demands, where each link includes one or more lines and each line can support one or more demands. Failure of one or more&#x2014;or even all&#x2014;of the lines/ports of a link will typically result in the independent rerouting of the affected demands along one or more link-detour paths. The flexibility afforded by recovery at the granularity of a demand supports the computation of more-optimal link-detour paths and a corresponding increase in sharing of network resources between disjoint failures. The network also addresses the restricted case where all demands on a line/port are recovered along the same link-detour path.

Link-based recovery with demand granularity in mesh networks

A method for determining primary and restoration paths for a new service in a mesh network involves (1) for each of a plurality of candidate primary/restoration path pairs for the new service, generating a path cost for each candidate pair, where the path cost for each restoration path is a function of the sum of the cost of links within the restoration path, and (2) selecting the primary and restoration paths for the new service from the plurality of candidate path pairs based on the path cost. If no sharing is possible, for low utilization links, the cost of links is a function of the administrative weight of the link, whereas for high utilization links, the link cost is a function of the inverse of the available capacity on the link. If sharing is possible, the cost is a function of the inverse of a sharing degree for the link.

Primary/restoration path calculation in mesh networks based on multiple-cost criteria

A shared mesh data network (SMDN) for path-based recovery at the packet level. In one implementation, a first link in the network is part of two or more different protection paths, where each protection path corresponds to a different primary path. A network manager determines how much protection bandwidth to reserve on the first link for the two or more protection paths in such a way that the protection bandwidth reserved on the first link is shared between the protection paths of the two or more primary paths. As such, the amount of protection bandwidth reserved on the first link can be less than the sum of the bandwidths of the two or more primary paths. The SMDN provides efficient sharing of protection capacity. Implementations of the SMDN are appropriate to multiprotocol label-switched (MPLS) optical networks.

Sharing restoration path bandwidth in mesh networks

A method for determining a restoration path corresponding to a primary path for a new service in a mesh network involves (1) generating path costs for candidate restoration paths for the new service, and (2) selecting, for the new service, the restoration path with the lowest path cost, where generating the path cost involves (a) determining, for each link Li in the candidate restoration path, a set B-Li-set of links protected by Li (b) determining, for each link Li, a set I-Li-set of links in the set B-Li-set that are also in the primary path (c) calculating, for each link Li, a link cost based on the set B-Li-set and the set I-Li-set, and (d) calculating the path cost based on a sum of the link costs. In some embodiments, the method includes an efficient scheme for representing, disseminating, storing, and updating sharing information in an OSPF-TE protocol context.

Restoration path calculation in mesh networks

A protected communication network utilizes a link-based recovery strategy that includes methods for calculating and distributing link-protection parameters and calculating primary and link-detour paths based on these parameters. These link-protection parameters support the computation of more-optimal link-detour paths and a corresponding increase in sharing of network resources between disjoint failures. A joint-optimization mechanism can be employed that considers both the cost of link-detour paths as well as the cost of links in candidate primary paths in the selection of a primary path for a demand. Information for the joint optimization is preferably distributed using link-state advertisements.

Calculation of link-detour paths in mesh networks

An extension to a connection setup protocol for establishment of a restoration path for a service in a mesh network involves, at a transit node along the restoration path, the steps of (1) receiving a service data structure having an identification of each link and transit node in a primary path for the service, and (2) determining whether to reserve additional protection bandwidth on an outgoing link incident to the transit node using the service data structure, wherein the outgoing link is part of the restoration path. In one or more embodiments, the service data structure includes identification of the service, identification of the outgoing link, and bandwidth of the service. In some cases, the extension involves reserving the additional protection bandwidth on the outgoing link, if the transit node determines that the protection bandwidth is required, based upon knowledge of the protection bandwidth already reserved on the outgoing link.

Connection set-up extension for restoration path establishment in mesh networks

A switch fabric for routing data has a switching stage configured between an input stage and an output stage. The input stage forwards the received data to the switching stage, which routes the data to the output stage, which transmits the data towards destinations. In one aspect, at least one input port can be programmably configured to store data in two or more input routing queues that are associated with a single output port, and at least one output port can be programmably configured to receive data from two or more output routing queues that are associated with a single input port. In another aspect, the output stage transmits status information about the output stage to the input stage, which uses the status information to generate bids to request connections through the switching stage. In yet another aspect, the switching stage transmits a grant/rejection signal to the input stage identifying (1) whether each bid is accepted or rejected and, if rejected, (2) a reason for rejecting the bid, and the input stage determines how to react to a rejected bid based on the reason the bid was rejected.

Three-stage switch fabric with input device features

A switch fabric for routing data has a switching stage configured between an input stage and an output stage. The input stage forwards the received data to the switching stage, which routes the data to the output stage, which transmits the data towards destinations. Each input device of the input stage transmits bids to the crossbar devices of the switching stage to request connections through the switching stage for routing the data to the output devices of the output stage. In one aspect, each crossbar device has (1) a bid arbitrator that determines whether to accept or reject each received bid, wherein, in response to a collision between multiple bids, the bid arbitrator accepts two or more of the colliding bids in a single time slot; and (2) memory for storing one or more accepted cells for the same output device, wherein the crossbar device can transmit grant signals for two or more accepted bids for the same output device in a single time slot. In another aspect, the bid arbitrator is configured to re-consider whether to accept a stored bid that was not accepted in a previous time slot.

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Montreal, Canada

Zbigniew M Dziong