Cisco Technology, Inc.

Hewlett-packard Development Company, L.p.

Robert H Thomas

Alex E Raj

Roger Antoine Karam

Prabhu Vaithilingam

Jean-Philippe Vasseur

David Delano Ward

Ijsbrand Wijnands

Sami Boutros

James Neil Guichard

Muthurajah Sivabalan

Anna Charny

Eric C Rosen

Jim Guichard

Syed Kamran Raza

Myron R Tuttle

Roy Michael Brooks

Jeff Apcar

Bin Mo

Matthew Henry Birkner

Herman W Chu

Eugene Chung

Samuel M S Lee

A method and apparatus for changing power class for a powered device are provided. During operation, a powered device, such as an IP telephone, receives power from a power source via a PoE device. In the event that the powered device detects connection to a second powered device, such as an IP telephone module, the powered device transmits a classification signal to the power source. Based upon the classification signal, the power source performs a powered device classification procedure to reclassify the powered device, such as according to an IEEE 802.3af standard, and provide an increase amount of power to the powered device. The powered device, in turn, provides a portion of the power to the modular device. The modular powered device, therefore, receives power directly from the first powered device and does not require additional equipment in order to operate.

Method and apparatus for changing power class for a powered device

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

In one embodiment, one or more tunnel mesh groups may be established in at least a portion of a computer network, where each tunnel mesh group corresponds to a differentiated routing profile. Traffic may then be received at the portion of the computer network, the traffic indicating a particular differentiated routing profile (e.g., based on a received label corresponding to the differentiated routing profile as advertised by the portion of the computer network). Accordingly, the traffic may be routed through the portion of the computer network along a tunnel of a particular tunnel mesh group corresponding to the particular differentiated routing profile traffic.

Differentiated routing using tunnels in a computer network

A given router in the core of a label-switching network identifies a group of routers to receive common label binding information for later routing packets along respective paths through the label-switching network. One way to identify which of multiple routers to include as a member of the group to receive the same label information is to analyze egress policies associated with downstream routers in the label-switching network. Based on this analysis, the given router identifies group members as routers having a substantially same egress policy as each other. The given router then allocates memory resources to store a common set of label information to be distributed to each member in the group of routers having the same egress policy. After populating the memory resources with label information, the given router distributes a common set of label information to each router in the group of routers.

Methods and apparatus for distributing label information

In one embodiment, a network device executes a Label Distribution Protocol (LDP) that sends LDP Hello messages at a default rate. The rate of sending LDP Hello messages is modified to accelerate the establishment of an LDP session between the network device and an LDP peer.

Acceleration of label distribution protocol (LDP) session setup

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

LDP label switching may be discontinued gracefully on one or more selected ones of multiple links interconnecting a pair of label switched routers (LSRs) while leaving label switching in operation on the remaining LDP-enabled links. Mechanisms for graceful shutdown of LDP on a selected link are added by way of modification to one or more of: e.g., LDP discovery Hello messages, LDP Label Withdraw/Label Release messages, LDP Notification messages.

Graceful shutdown of LDP on specific interfaces between label switched routers

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

A tag-switching router on a tag-switching network establishing a single tag distribution protocol (TDP) session with a peer for the advertisement of tag bindings shared by two or more interfaces and contemporaneously establishing with the peer one or more additional TDP sessions for the advertisement of tag bindings dedicated for use by specific interfaces. Each router interface has an assigned tag space comprised incoming tags that are appended by the peer to input data packets forwarded by the peer. A new Hello message carried in a TDP protocol data unit (PDU) is introduced for use in a TDP discovery mechanism. The router periodically multicasts a specific Hello message from each tag-switching enabled interface and a router TDP identifier in the TDP PDU header identifies the tag space that the router has assigned to the interface. When the router receives a Hello message from the peer at one of its interfaces, the router records the peer TDP identifier in a record associated with the interface to create a link adjacency. The router and peer establish a conventional TDP session to exchange tag binding sets. The router transmits to the peer a Bind message containing advertised tag bindings which, in turn, contain the incoming tags for the tag space identified by the router TDP identifier in the TDP PDU header. The router receives from the peer a Bind message from the peer containing learned tag bindings which, in turn, contain the outgoing tags for the tag space identified by the peer TDP identifier in the TDP PDU header. The router appends outgoing tags to received data packets having destination addresses bound to the learned tag bindings and forwards the tagged received data packets to the peer from the associated interface.

Discovery and tag space identifiers in a tag distribution protocol (TDP)

A method and system of controlling a cooling fan of a computer system including a power supply unit. The method includes sensing a power load of the power supply unit. A reference air temperature of the computer system is also sensed. Finally, a fan setting is determined based upon the sensed power load and the sensed reference air temperature. By basing the fan setting on both reference temperature and actual power supply load, the method and system effectively minimizes cooling fan operation, and thus resulting acoustic noise, when a computer system is operating at less than full capacity. In one preferred embodiment, a look-up table is provided in which a plurality of fan settings are included, each fan setting being based upon a correlation of power supply load and reference temperature. The method and system of the present invention is particularly useful with high-end, server-type computer systems being used for low-end applications, and is readily applied to multiple platforms.

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Lexington, MA, United States of America

Robert H Thomas