Cisco Technology, Inc.

Cabletron Systems, Inc.

Alex E Raj

Robert H Thomas

Prabhu Vaithilingam

Ijsbrand Wijnands

Anna Charny

Eric C Rosen

Roger H Dev

Wallace E Matthews

Jeremy Lawrence

Rodolphe Figaro

David K Snay

Peter Kline

Hseu-Chuan Tsai

John F McGlauphlin

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.

Method and apparatus for forwarding label distribution protocol multicast traffic during fast reroute

A technique for breaking a loop caused by looping alternate paths associated with a prefix in a communications network. One or more non-looping alternate paths associated with the prefix that exclude a first node in the communications network are identified. One or more alternate paths from nodes in the loop that are associated with the prefix are identified. An identified path that intersects with an identified non-looping path is established as an alternate path associated with the prefix at a node in the loop.

Technique for breaking loops in a communications network

A method, apparatus and computer program product for minimizing or preventing duplicate traffic during point to multipoint tree switching in a network. In its operation, embodiments disclosed herein utilize control plane trigger mechanisms to handle the receipt of duplicate traffic by network entities after the occurrence of a network failure event. Generally, the control plane trigger mechanism prevents a network entity from processing multicast traffic from both old and new upstream data paths resulting from typical network convergence procedures. The methods and apparatus describe herein apply to standard rerouting procedures as well as fast rerouting procedures for multicast traffic in a network.

Methods and apparatus for minimizing duplicate traffic during point to multipoint tree switching in a network

A method of distributing labels in a label distribution protocol multicast network having a root node and at least one leaf node comprises the steps, performed at a receiving node, of receiving a label and path vector from a distributing node, carrying out loop or convergence detection from the received path vector and, if convergence or no loop is detected, sending a receiving node label and path vector to its nexthop node in the network.

Method and apparatus for distributing labels in a label distribution protocol multicast network

A method and apparatus method for providing fast rerouting in a network is presented. The method and apparatus assign a first local label for a prefix, and assign a second local label for the prefix. The first local label is advertised to an upstream peer and the second local label is advertised to a downstream peer. A forwarding entry from the first local label for a prefix is switched to the second local label for the prefix when a failure of a link or next hop is detected.

Method and apparatus using multiprotocol label switching (MPLS) label distribution protocol (LDP) to establish label switching paths (LSPS) for directed forwarding

The invention provides unique architectures and techniques for routing redundancy in a data switch configured to use label switching. Multiple label switch controllers (LSCs) each operate concurrently but independently of each other to provide routes through a data switching mechanism. Preferred embodiments provide a plurality of LSCs offering MPLS capabilities coupled to a single switch, such as an ATM switch. The similarly configured LSCs each can concurrently support a route for data (e.g., labeled ATM cells) within the data switching mechanism in parallel, thereby providing the ability to support redundant and multiple parallel data networks. The configuration is called a label switch router (LSR). A fully-meshed embodiment allows selected routes to share bandwidth on ports, while a fully parallel embodiment provides separate ports for selected routes. Since each LSC provides parallel routes with the other LSCs in an LSR, a communications between an LSR and a label edge router (LER) can use multipath routing to concurrently distribute data equally across the parallel routes for each destination. Alternatively, unipath routing techniques can select one route for use for each destination from the available routes concurrently offered by each LSC. In the event of a failure of one of the LSCs, multipath routing implementations can exclude transmission of data onto the failed network, while continuing to use the other parallel networks supported by non-failed LSCs in a concurrent manner. Alternatively, if a failure occurs with unipath routing, a new route offered by another LSC can be selected for data transfers. In either case, the LSC that fails does not need to provide state or connection information to the LSCs that operate subsequently to the failure, since they are already configured in parallel to support the same route. Upon an LSC failure, switch resources such as bandwidth that were used by the failed LSC are made available to the remaining non-failed LSCs. The design allows failures are handled gracefully without diminished network capacity or data loss resulting in a highly reliable routing capability provided within connection-based or circuit-switched networks.

Apparatus and methods providing redundant routing in a switched network device

A modular data network protocol conformance test system is designed to make distinct the key functionality that is required in protocol conformance testing such that the system can be reused across different platform testing, protocol testing, and network topology. As a result, in its current design, it can be used to test devices as distinct as cable modems, routers, and tag-switching routers. Consequently, the system has a packet generation module that generates send packets for transmission to the UUT (unit under test) and that analyzes the receive packets from the UUT. A separate network handling module transfers the send packets to and acquires the receive packets from the UUT. 13

Data network protocol conformance test system

A method for selecting a communication path over which to send a communication load between a first station and a second station in a communication network, in which the communication network has a plurality of possible communication paths between the first and second stations. The method comprises identifying at least one of the possible communication paths between the first and second stations, determining a first path metric for each identified path, the first path metric having a value that may vary as distribution of the load across the network varies and selecting one of the at least one identified paths based on the value of the first path metric for each identified path.

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Westford, MA, United States of America

Alex E Raj