371 results about "Backup path" patented technology

A method for managing multiple active paths among a plurality of network switches to identify and select an alternate path in response to failure of a path from a switch to a device. Load balancing protocols of the present invention enable the simultaneous use of multiple paths between network devices through a mesh of compliant network switches. When a port of a network switch fails (or the link connected to a port fails), a switch in accordance with the present invention selects an alternate port which may be used for forwarding packets to devices normally reached through the failed port. Networks switches operable in accordance with the structures and protocols of the present invention exchange messages to identify potential alternate paths. A potential alternate path is used to send a query message to a neighboring network switch to determine if a path to the identified devices is available through the neighboring network switch. Such query messages are propagated through all intermediate network switches between the switch sensing the failed port up to the identified network device. Acknowledgment messages are returned to verify potential availability of an alternate path. Where an intermediate network switch determines that the complete path is not available through it to the identified device, or where a potentially better path exists, a regenerated query message so indicating is returned along the path that initiated the query message.

Methods and apparatus for rerouting network traffic are described herein. In one embodiment, an example of process includes maintaining as a part of a routing table of a network element information regarding one or more backup links leading to a node using label switched protocols (LSPs), the node being adjacent to the network element, and in response to a failure of a primary link coupling the network element to the node, the network element rerouting network traffic to the node via the one or more backup paths without having to notifying and waiting for a response from a headend node that originates the network traffic. Other methods and apparatuses are also described.

A method of constructing a backup path in an autonomous system (AS) for failure of a first inter-AS link serving a first set of prefixes is described. The method comprises identifying an alternate inter-AS link serving said plurality of prefixes and constructing a tunnel thereto.

Techniques are described to automatically activate and deactivate standby backup paths in response to changing bandwidth requirements in an adaptive private network (APN). The APN is configured with one or more regular active wide area network (WAN) links in an active mode and an on-demand WAN link in a standby mode. The on-demand WAN link is activated to supplement the conduit bandwidth when an available bandwidth of the conduit falls below a pre-specified trigger bandwidth threshold and the conduit bandwidth usage exceeds a usage threshold of a bandwidth of the conduit that is being supplied by the active paths (BW_C). The on-demand WAN link is deactivated to standby mode when an available bandwidth of the conduit is above the pre-specified trigger bandwidth threshold and the conduit bandwidth usage drops below the usage threshold of BW_C. Techniques for adaptive and active bandwidth testing of WAN links in an APN are also described.

A method of constructing a backup path in an autonomous system (AS) for failure of an inter-AS link is described. The method comprises identifying an alternate inter-AS path and constructing a tunnel to an end point on the alternate path.

A new technique for fast alternate-path automatic rerouting of labeled data packets normally routed over a predetermined primary label switched path upon failure or congestion in the primary path.

In a disclosed backup path bandwidth keeping method for keeping bandwidth of a backup path to which an active path is switched when the active path becomes unavailable in nodes of a communication network, each node is connected to the same destination, and the method includes a backup path bandwidth keeping phase, for M (M is a natural number equal to or less than L) channels in L (L is a natural number) channels kept as backup path bandwidth, for notifying a destination-side node existing in a destination side of the backup path of identification number information of the M channels to be kept and identification information indicating that a path for which the bandwidth is to be kept is a backup path.

A method of implementing a backup path in an autonomous system (AS) for failure of an inter-AS link is described. The method comprises forwarding data elements destined for the failed link via a backup path and including a loop prevention attribute in the packet.

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 SONET network terminated by routers includes working paths and backup paths. The routers pre-establishes in their link state data bases the links in both for both the working and backup paths. However, the links involved in the backup paths are given higher costs, then the links working paths, that the routers select only the links in the working path. If there is a failure in a link in a working path, an APS arrangement provides rapid switchover of the optical links so as to substitute one or more links in the corresponding backup path. This is accomplished by changing the relative costs of the working and backup links involved, so that the routers select the backup links for their routing tables.

Restorable paths in an information network are established in response to arriving traffic requests. Requests are received at a first node of the network for transmission of traffic to a second node of the network, and each request specifies a desired transmission bandwidth for an active and a backup path to be established between the nodes. Potential active links for an active path are identified in response to a given request, and potential backup links to form a backup path for restoring the active path, are also identified in response to the given request. An active and a backup path are then formulated for each given request from among the potential active links and the potential backup links that were identified in response to the given request.

A system and method for providing fault tolerance in a network telephony system. Signaling messages according to a signaling protocol, such as the SIP protocol, are modified to include a path attribute with a network address corresponding to a backup proxy server. When a primary proxy server is supported by a backup proxy server, the primary proxy server inserts the Alternate Path tag into one or more signaling messages. When a network entity sends a message, it checks the message to identify the primary proxy server. Upon receiving a failure or timeout when attempting to send to the primary proxy server, the sending network entity should try the backup proxy server specified in the path attribute. When the backup proxy server receives the message, it may modify the message to specify the new routing path. As a result, subsequent messages get routed properly using the backup proxy server.

A computer apparatus comprising a processor and a forwarding engine arranged to forward LDP multicast traffic along a multicast tree having a primary and a backup path in a converged network topology, the processor being configured to cause the forwarding engine to forward traffic via the backup path upon a topology change and send a changed topology label and path vector to at least one neighbor node in the changed topology.

A computer network has a plurality of routers that deliver data packets to the network via a plurality of links. At least one router provides automatic protection switching in the event of a link failure. The at least one router includes a plurality of data interfaces for streams of data packets to enter and exit the at least one router; and a backup controller. The backup controller includes a backup path manager, a link monitor, and a backup packet processor. For at least one link of the routing node, the backup path manager identifies a backup routing path for forwarding affected data packets in the event of a failure of the at least one link. The link monitor monitors the plurality of links to determine when a link fails. When a link which has a backup routing path fails, the backup packet processor attaches backup routing path instructions to affected data packets routed over the failed link, and forwards the affected data packets via the backup routing path.

A telecommunications system includes a network for transporting packets on a path between selected subscriber end points. The network has multiple nodes connected by links, with each node (a) pairing the forward and backward paths of a connection and (b) allowing for the injection of messages in the backward direction of a connection from any node in the path without needing to consult a higher OSI layer. A system is also provided for protecting connection paths for transporting data packets through an Ethernet telecommunications network having a multiplicity of nodes interconnected by a multiplicity of links. Primary and backup paths are provided through the network for each of multiple connections, with each path including multiple links. Data packets arriving at a first node common to the primary and backup paths are duplicated, and one of the duplicate packets is transported over the primary path, the other duplicate packet is transported over the backup path, and the duplicate packets are recombined at a second node common to the primary and backup paths.

The invention realizes defect indication on a multipoint logical path and switching of the logical path when the multipoint logical path is configured using a transfer protocol of configuring a logical path, typified by MPLS etc., in a ring network. Two routes of the multipoint logical paths, a working path and a backup path, are set up. Each of them not only transmits a frame transmitted from a transmitting end node to multicast receiving end nodes but also forwards the frame to the transmitting end node and terminates it also at the transmitting end node after making it go around the ring. Any node that detects a defect transmits a forward defect indication frame to a multipoint logical path in which the defect occurs. The transmitting end node having received the forward defect indication frame halts the use of the notified multipoint logical path, and transmits a frame in another path in which the forward defect indication frame is not received within a fixed time period. Moreover, when the forward defect indication frame is received from the both multipoint logical paths, the transmitting end node copies the frame and forwards them to the both multipoint logical paths.

The invention discloses a control method of an SDN controller. The method comprises the steps of calculating backup paths of a main path according to an obtained software-defined network (SDN) topology and expenses of each link, distributing marker bits for marking the backup paths to the backup paths, and issuing flow table items to SDN forwarding devices on the backup paths according to the backup paths and the corresponding marker bits so that messages can be matched with the flow table items to be forwarded through the backup paths when the main path breaks down. The invention further discloses the SDN controller. By the adoption of the SDN controller and the control method of the SDN controller, it is ensured that the flow obtained before the SDN controller calculates and processes new flow is not lost when the link for forwarding the flow in a network is broken or the topology changes.

A graceful shutdown technique modifies a routing protocol to allow an intermediate node, such as a router, to announce to its peer routers (peers) its intention to be gracefully shutdown and removed from service in a network. By announcing its intention to be removed from service, the shutdown router closes (terminates) all connections with its peers and all original routes advertised on those connections are removed (withdrawn) from service. According to the inventive technique, the shutdown router may continue forwarding packets over the network for a “grace” period of time, i.e., the router maintains the validity of those original routes so that packets mapped to the routes are not dropped (at least during the grace period). The grace period also allows backup paths to be propagated to each peer and put into service prior to a final withdrawal of the shutdown router's paths from a forwarding information base of the peer. Thus, the grace period enables the network to continue using the shutdown router as a next hop as it re-converges to use the alternate, backup paths.

A packet forwarding apparatus is provided which can minimize traffic detoured to a backup path liable to be degraded in communication quality in the event of a link failure to thereby improve the communication quality. To this end, a technique is provided in which an output label decision unit and an output physical port ordinal number search unit which are included in a destination decision unit decide, from a header of an input packet, an output label of the packet, a first logical link to which the packet is to be outputted and a first physical link constituting the first logical link. When a failure takes place in the first physical link, the detour decision unit changes the output label to a backup label and the first physical link to a second physical link constituting a second logical link.

The time required for a path recalculation and a path switching upon occurrence of a failure is shortened. A path generation unit of a transport control server (TCS) S-1 generates the normal path information in accordance with the topology information of a network and the resource information which are set. Also, the path generation unit generates in advance the backup path information for occurrence of the failure based on the prediction topology information and the prediction resource information which have been modified in accordance with a predicted failure position. A path information notification unit of the TCS (S-1) notifies nodes N of the generated normal path information. A failure information acquisition unit of the TCS (S-1) detects the occurrence of the failure. If the occurrence of the failure is detected, the path information notification unit notifies the nodes N of the backup path information that is stored.