37 results about "Shared risk link group" patented technology

In a communications network where multiple shared risk link groups are formed by links having a common risk, unreserved bandwidths are defined corresponding to all SRLG's and a maximum bandwidth of each link is set as an initial value of each of the defined unreserved bandwidths when a working path or a protection path of “1+1” or “1:1” recovery type is requested. When a protection path of “shared” recovery type is requested, unreserved bandwidths are defined corresponding to the SRLG's to which the links of its corresponding working path belong and a maximum bandwidth of each link is set as an initial value to each of the defined unreserved bandwidths. The bandwidth of the working or protection path is subtracted from each of the unreserved bandwidths. The request is rejected if a minimum of the subtracted values is smaller than a threshold.

A method and apparatus are disclosed for performing a shortest path first network routing path determination in a data communications network based in part on information about links that are associated as shared risk link groups. Micro-loops are avoided in computing shortest path first trees by considering whether links are within shared risk link groups. In a first approach, for each link state packet in a link state database, listed adjacencies are removed if the link between the node originating the LSP and the reported adjacency belongs to a shared risk link group for which one component (local link) is known as down, and a shortest path first computation is then performed. In a second approach, during the SPT computation and after having added a first node to a path, each neighboring node is added to a tentative tree if and only if, a link between the first node and the neighboring node does not belong to a shared risk link group for which one component (local link) is known as down.

A method of setting shared risk link group identification information (SRLG ID) which is one of link properties employed for calculating a route for a path in a communications network including nodes and links for interconnecting the nodes, and indicates a link group which shares resources, comprises the step of assigning a number of SRLG IDs to the link group in accordance with a failure rate of resources shared by that link group. A route calculating method for calculating routes for a working path and a standby path comprises the step of calculating the routes such that a minimum number of SRLG IDs duplicate between all links on the route of the working path and all links on the route of the standby path.

Drop port based shared risk link group (SRLG) systems and methods assign SRLG information to drop ports in another level or layer of a network. Thus, drop side SRLG information can be shared between different networks or layers enabling a combination with line side SRLG information within a network to identify and prevent single points of failure across the networks. Typically, SRLG details are assigned to line ports (NNI ports) within a network and this information is not shared with external networks or network layers for routing a connection through the network and the external networks. By assigning SRLG details to a drop port, this information can be relayed between the network and the external networks and considered when planning a route through all of the networks.

An efficient trap avoidance and shared protection method in a survivable network with shared risk link groups. The invention includes a fast and efficient heuristic algorithm for avoiding traps, an algorithm, which may also be applied effectively to shared SRLG protection. Compared to other existing algorithms, the algorithm embodied in the present invention runs much faster, and yet falls into few traps, and achieves a much higher bandwidth efficiency. This technology can be applied to MPLS, ATM, SONET, WDM, and other high-speed survivable network designs.

In a communications network where multiple shared risk link groups are formed by links having a common risk, unreserved bandwidths are defined corresponding to all SRLG's and a maximum bandwidth of each link is set as an initial value of each of the defined unreserved bandwidths when a working path or a protection path of "1+1" or "1:1" recovery type is requested. When a protection path of "shared" recovery type is requested, unreserved bandwidths are defined corresponding to the SRLG's to which the links of its corresponding working path belong and a maximum bandwidth of each link is set as an initial value to each of the defined unreserved bandwidths. The bandwidth of the working or protection path is subtracted from each of the unreserved bandwidths. The request is rejected if a minimum of the subtracted values is smaller than a threshold.

A number of techniques are described for routing methods that improve resistance to faults affecting groups of links subject to common risks. One of these techniques accounts for failure potentials in physical networks by considering shared risk link groups separately from performance and costs metrics in determining a primary routing path and a backup path. A shared risk link group (SRLG) is an attribute attached to a link to identify edges that have physical links in common and can therefore be simultaneously disrupted due to a single fault. Another technique considers node disjointness and provides a solution of two paths that are as node disjoint as possible and minimizes administrative costs. The techniques may further be combined in a priority order thereby providing a solution of at least two paths that are strictly SRLG disjoint, as node-disjoint as possible, and have minimum administrative costs. Due to the priority order of evaluation and typical network physical configurations of links, with the links associated common fault SRLGs, the priority ordering technique is very efficient in determining at least two paths for routing between a source and destination node.

The invention discloses a method and a system for network routing selection. The system comprises the following modules of a k-Shortest Path algorithm module, a work routing calculation module, a 2:N recovery routing calculation module, a 2:N recovery routing calculation module and a function control module, wherein the k-Shortest Path algorithm module is used for calculating an alternative routing set for services; the work routing calculation module is used for selecting a shortest path from the alternative routing set as a working routing, and providing a sharing recovery condition and a routing-independent constraint condition for the 2:N recovery routing calculation module; the work resource allocation module is used for allocating a channel resource for the work routing; the 2:N recovery routing calculation module is used for selecting two SRLG (Shared Risk Link Group)-independent and work routing SRLG-independent recovery routings from the alternative routing set to form a shortest recovery routing group according to the sharing recovery condition and the routing-independent constraint condition; the 2: N recovery resource allocation module is used for allocating the channel resource for the recovery routings in the shortest recovery routing group; and the function control module is used for controlling the works of other modules and coordinating the logical relation among the modules. With the method and the system, the channel resource is saved, and the network security is improved.

A scheme to achieve fast recovery from SRLG failures in the IP layer is described. An exemplary scheme, called multi-section shortest path first (“MSSPF”), builds on the idea of IP Fast Reroute (“IPFRR”), guarantees 100% recovery of SRLG failures and causes no dead loops. Given a source node, a destination node, and a shared risk group failure on a next hop from the source node to the destination node, failure recovery information may be determined by (1) accepting a graph representing network topology information including the source node and the destination node, (2) determining a node which is able to reach the destination node using a route which does not include the source node, wherein a path from the source node to the determined node is not affected by the shared risk group failure, and (3) storing, in association with the shared risk group failure, both (i) a network address associated with the determined node and (ii) an alternative output port of the source node using the shortest path from the source node to the determined node.

A method of setting shared risk link group identification information (SRLG ID) which is one of link properties employed for calculating a route for a path in a communications network including nodes and links for interconnecting the nodes, and indicates a link group which shares resources, comprises the step of assigning a number of SRLG IDs to the link group in accordance with a failure rate of resources shared by that link group. A route calculating method for calculating routes for a working path and a standby path comprises the step of calculating the routes such that a minimum number of SRLG IDs duplicate between all links on the route of the working path and all links on the route of the standby path.

Drop port based shared risk link group (SRLG) systems and methods assign SRLG information to drop ports in another level or layer of a network. Thus, drop side SRLG information can be shared between different networks or layers enabling a combination with line side SRLG information within a network to identify and prevent single points of failure across the networks. Typically, SRLG details are assigned to line ports (NNI ports) within a network and this information is not shared with external networks or network layers for routing a connection through the network and the external networks. By assigning SRLG details to a drop port, this information can be relayed between the network and the external networks and considered when planning a route through all of the networks.

The embodiment of the invention discloses a path selection method and a path selection device, which are used for selecting a target path for transmitting service data based on attribute information of an SRLG bearing an OMS. Specifically, the path selection device determines an optical multiplexing segment (OMS) topology between a source node and a destination node, and obtains attribute information of a shared risk link group (SRLG) corresponding to each OMS. Then, a target path is selected according to the attribute information of the SRLG, the target path being used for transmitting traffic data from the source node to the destination node through at least one OMS of the plurality of OMSs. As the attribute information of the SRLG can reflect the actual attribute of the physical optical fiber section / optical cable section, the target path with lower fault risk is selected according to the attribute of the SRLG, which is beneficial to improving the reliability of service transmission.

The present application provides a method and device for detecting a shared risk link group. The method includes: respectively recording a first curve and a second curve of the power corresponding to the backlight in the first link to be tested and the second link to be tested as a function of time; calculating the first curve and the second curve The similarity value of the curve, and based on the similarity value, it is judged whether the first link under test and the second link under test are in the same shared risk link group. A method and device for detecting a shared risk link group provided in an embodiment of the present application, by testing the power characteristics of the backlight of the detection light in the link to be tested, and judging the link group to be tested based on the one-dimensional power characteristic Whether they are in the same shared risk link group is relatively simple in practical applications.