241 results about "Path computation element" patented technology

A technique efficiently load balances traffic engineering (TE) label switched paths (LSPs) from a head-end node to a tail-end node of a computer network. The novel load balancing technique identifies (e.g., at the head-end node or a path computation element, PCE) a set of paths with equal costs from the head-end node to the tail-end node, where each path of the set is composed of one or more associated links. “Link values” such as, e.g., the number of unconstrained TE-LSPs on the link, the amount of available bandwidth on the link, or the percent of total available bandwidth already in use on the link, are applied to each link of each path. The most restrictive link values (link availability) of each path of the set, such as, e.g., the link with the lowest amount of available bandwidth, etc., are then compared. Upon comparing the link availability, the novel technique load balances established and/or new TE-LSPs from the head-end node to the tail-end node over the set of paths accordingly.

Systems and methods for computing the paths of MPLS Traffic Engineering LSPs across Autonomous System and/or area boundaries. A distributed path computation algorithm exploits multiple path computation elements (PCEs) to develop a virtual shortest path tree (VSPT) resulting in computation of an end-to-end optimal (shortest) path. In some implementations, the VSPT is computed recursively across all the Autonomous Systems and/or areas between the head-end and tail-end of the Traffic Engineering LSP.

A technique efficiently routes Internet Protocol (IP) traffic on paths between customer edge devices (CEs) across a provider network (“CE-CE paths”) in a computer network. According to the novel technique, a path computation element (PCE), e.g., a provider edge device (PE), may learn dynamic link attribute information of remote links from the provider network to one or more remote CEs (e.g., “PE-CE links” or “CE-PE links”). A multi-homed requesting CE requests from the PCE a set of CE-CE path metrics (e.g., costs) to one or more remote destination address prefixes, e.g., via each multihomed CE-PE link from the requesting CE. In response to the request, the PCE computes the set of available CE-CE paths and current metrics to the remote destination address prefixes and returns the corresponding CE-CE path metrics to the requesting CE. The requesting CE modifies its IP forwarding entries accordingly in order to perform IP traffic routing corresponding to the CE-CE path metrics (e.g., asymmetrical load balancing) across its multi-homed CE-PE links.

A technique calculates a shortest path for a traffic engineering (TE) label switched path (LSP) from a head-end node in a local domain to a tail-end node of a remote domain in a computer network. The novel path calculation technique determines a set of different remote domains through which the TE-LSP may traverse to reach the tail-end node (e.g., along “domain routes”). Once the set of possible routes is determined, the head-end node sends a path computation request to one or more path computation elements (PCEs) of its local domain requesting a computed path for each domain route. Upon receiving path responses for each possible domain route, the head-end node selects the optimal (shortest) path, and establishes the TE-LSP accordingly.

A technique computes a traffic engineering (TE) label switched path (LSP) that spans multiple domains of a computer network from a head-end node of a local domain to a tail-end node of a remote domain. The novel inter-domain TE-LSP computation technique comprises a computation algorithm executed by the head-end node, which utilizes Path Computation Elements (PCEs) located within the remote domains (i.e., other than the local domain). Specifically, the head-end node requests path segments from a PCE in each of the remote domains, in which the path segments represent paths between all entry border routers to either all exit border routers of the particular remote domain (i.e., through the domain), or to the tail-end node. Upon receiving path segments from each remote domain, the head-end node combines the path segments with local domain information, and performs a forward path computation from the head-end node to the tail-end node to find the best (i.e., “shortest”) path.

A packet network of interconnected nodes employing dynamic backup routing of a Network Tunnel Path (NTP) allocates an active and backup path to the NTP based upon detection of a network failure. Dynamic backup routing employs local restoration to determine the allocation of, and, in operation, to switch between, a primary/active path and a secondary/backup path. Switching from the active path is based on a backup path determined with iterative shortest-path computations with link weights assigned based on the cost of using a link to backup a given link. Costs may be assigned based on single-link failure or single element (node or link) failure. Link weights are derived by assigning usage costs to links for inclusion in a backup path, and minimizing the costs with respect to a predefined criterion.

A technique retrieves computed path segments across one or more domains of a computer network in accordance with a stateful (“semi-stateful”) path computation element (PCE) model. The stateful PCE model includes a data structure configured to store one or more path segments computed by a PCE in response to a path computation request issued by a Path Computation Client (PCC). Notably, each computed path segment stored in the data structure is identified by an associated path-key value (“path key”). The path segment and path key contents of the data structure are temporarily saved (“cached”) at a predetermined location in the network for a configurable period of time.

A technique efficiently selects a path computation element (PCE) to compute a path between nodes of a computer network. The PCE selection technique is illustratively based on dynamic advertisements of the PCE's available path computation resources, namely a predictive response time (PRT). To that end, the novel technique enables one or more PCEs to dynamically send (advertise) their available path computation resources to one or more path computation clients (PCCs). In addition, the technique enables the PCC to efficiently select a PCE (or set of PCEs) to service a path computation request based upon those available resources.

A technique performs an efficient constrained shortest path first (CSPF) optimization of Traffic Engineering (TE) Label Switched Paths (LSPs) in a computer network. The novel CSPF technique is triggered upon the detection of an event in the computer network that could create a more optimal path, such as, e.g., a new or restored network element or increased path resources. Once the novel CSPF technique is triggered, the computing node (e.g., a head-end node of the TE-LSP or a Path Computation Element, PCE) determines the set of nodes adjacent to the event, and further determines which of those adjacent nodes are within the TE-LSP (“attached nodes”). The computing node performs a CSPF computation rooted at the closest attached node to determine whether a new computed path cost is less than a current path cost (e.g., by a configurable amount), and if so, triggers optimization of the TE-LSP along the new path.

A route computation method includes: receiving, by a first bottom-level PCE, a path computation command, performing a route computation on a routing domain managed thereby, obtaining and sending a path segment set with a first node to an upper-level PCE thereof; sending, by the upper-level PCE receiving the path segment set sent by a lower-level PCE, the path computation command to another lower-level PCE according to routing domains that a path to be established between the first node and a second node sequentially passes through, receiving path segment sets sent by all lower-level PCEs, and combining and sending all the received path segment sets to an upper-level PCE thereof, until a top-level PCE receives path segment sets sent by all lower-level PCEs thereof; and combining, by the top-level PCE, all the received path segment sets to generate a set of paths between the first node and the second node.

A technique retrieves computed path segments across one or more domains of a computer network in accordance with a stateless Path Computation Element (PCE) model. The stateless PCE model includes one or more PCEs configured to compute one or more path segments through the domains in response to a path computation request issued by, e.g., a Path Computation Client (PCC). Notably, each computed path segment is encrypted as a data structure to preserve confidentiality across the domains. Each PCE then cooperates to return a path computation response, including the encrypted path segments and an explicit route object (ERO) containing compressed path descriptions of the computed path segments, to the PCC.

A mechanism to alleviate bandwidth fragmentation in a network employing path computation element(s) to place MPLS Traffic Engineering tunnels. One application is a multiple Autonomous System or multiple area network employing distributed computation of MPLS Traffic Engineering LSPs. A particular path computation element may determine that bandwidth fragmentation is present based on monitoring of path computation failures where desired paths are blocked due to bandwidth constraints. In response to the detected bandwidth fragmentation condition, the path computation element floods a routing notification within its Autonomous System or area. Nodes respond to the routing notification by requesting reoptimization of their own previously requested Traffic Engineering LSPs allowing the path computation element an opportunity to alleviate bandwidth fragmentation.

A technique dynamically enforces inter-domain policy and quality of service (QoS) for Traffic Engineering (TE) Label Switched Paths (LSPs) between a local domain and a remote domain in a computer network. According to the enforcement technique, a Path Computation Element (PCE) of the local domain receives a path computation request for an inter-domain TE-LSP from the remote domain, and triggers a policy verification procedure at a Policy Decision Point (PDP) of the local domain. The PDP determines whether the requested TE-LSP is allowed based on configured policy for the remote domain and previously established TE-LSPs from the remote domain. In the event the requested TE-LSP is allowed and subsequently established, a Policy Enforcement Point (PEP) along the TE-LSP, e.g., a border router of the local domain or a dedicated server, updates the PDP with the state of the TE-LSP. In response to the update, the PDP returns a QoS template indicating configured QoS guidelines the PEP must enforce for that TE-LSP. If the TE-LSP is eventually torn down, the PEP again updates the PDP with the state of the TE-LSP.

A method and system for multi-domain route computation. In the invention, Path Computation Elements (PCEs) are placed in different layers and computation domains between upper and lower layer PCEs are mapped so that a computation task is divided into multiple computation tasks layer by layer and that the multi-domain route computation is finally fulfilled. The invention separates route computation from signaling and runs route computation tasks in parallel. Route establishment is done by signaling after route computation. The present invention may realize route computation based on complex Traffic Engineering (TE) constraints and enable end-to-end diverse route computation. The invention places PCEs in layers, allowing good scalability and high computation efficiency. The present invention is applicable to the Automatically Switched Optical Network (ASON) and the Multi-Protocol Label Switched Network Traffic Engineering (MPLS-TE) network.

The invention discloses a client distributed path computation method based on a software defined network architecture. The client distributed path computation method comprises the following steps: a user obtains network topology and linkcost information from a network controller through a northbound interface of a controller, calculates the path on the basis, determines route and flow distribution, and submits a route request to the controller; the network controller is responsible for updating the network topology and link state, and issuing a flow statement to data forwarding equipment according to the route selection of the user. Through the route calculation, the user participates in the network control to achieve the distributed optimization during the use process of network resources; meanwhile, the controller provides network topology information for the user, and can achieve the virtualization of the network resources and functions for the user and the optimal configuration and the integrated use of the network resources. Through the application of the method, the user can get great rights within a network safety range, the network transparency is improved, and an SDN frame serves for the user.

A technique triggers optimization of a traffic engineering (TE) label switched path (LSP) that spans multiple domains of a computer network from a head-end node of a local domain to a tail-end node of a remote domain. The technique is based on the detection of an event in the remote domain (“event domain”) that could create a more optimal TE-LSP, such as, e.g., restoration of a network element or increased available bandwidth. Specifically, a path computation element (PCE) in the event domain learns of the event and notifies other PCEs of the event through an event notification. These PCEs then flood an event notification to label switched routers (LSRs) in their respective domain. Upon receiving the notification, if an LSR has one or more TE-LSPs (or pending TE-LSPs), it responds to the PCE with an optimization request for the TE-LSPs. The PCE determines whether a particular TE-LSP may benefit from optimization based on the event domain (i.e., whether the TE-LSP uses the event domain), and processes the request accordingly.

In an embodiment, a system routes a new data stream from a source to a destination through a plurality of forwarding devices interconnected with links. The system includes a control device that receives a request to create a path through the plurality of interconnected forwarding devices for a new data stream and determines a type of the new data stream. A data flow database stores historical usage characteristics of data streams having the determined type. A path computation module determines, based on the historical usage characteristics of data streams having the determined type, the requested path through plurality of interconnected forwarding devices from the source to the destination.

The invention relates to a device and a method for recovering service. The device essentially comprises a path computation element (PCE) and network nodes. The method essentially comprises the steps that: the nodes reports network failure information to the PCE; the PEC calculates LSP route of recovered rerouting according to the saved network information, obtained failure information and the information of label switching path (LSP) influenced by the failure; according to the LSP route of the recovered rerouting, corresponding recovered LSP is established so as to realize the recovery of the service. Utilization of the method of the invention can ensures that when failure occurs to the network, the PCE establishes the optimal recovered rerouting and shortens the time of rerouting according to the obtained network topology information of the whole network, the link information, the LSP information and the failure information reported by the nodes.

A path computation method includes defining photonic constraints associated with a network, wherein the photonic constraints include wavelength capability constraints at each node in the network, wavelength availability constraints at each node in the network, and nodal connectivity constraints of each node in the network, and performing a constrained path computation in the network using Dijkstra's algorithm on a graph model of the network with the photonic constraints considered therein. An optical network includes a plurality of interconnected nodes each including wavelength capability constraints, wavelength availability constraints, and nodal connectivity constraints, and a path computation element associated with the plurality of interconnected photonic nodes, wherein the path computation element is configured to perform a constrained path computation through the plurality of interconnected nodes using Dijkstra's algorithm on a graph model with the photonic constraints considered therein.