578 results about "Label switching" patented technology

In an MPLS network, multicast, broadcast and address learning belonging to the layer 2 functions are realized. An ingress router comprises a frame receiving unit, a determining unit, a first frame transmitting unit, a physical address table for multicast, a label switching unit, a tunnel label table, a VCID giving unit, a L2 header creating unit and a second frame transmitting unit. The load on the network is suppressed, the band is efficiently used, and wasteful frame duplication and frame forwarding between edge routers are avoided.

A method for avoiding loops from forming when setting up label switched paths is provided. The method uses a Label Splicing Message is followed by an Acknowledgment message to determine if loops are formed in the process of joining a new node or subtree to a multicast MPLS tree. By verifying that the path towards the root of the MPLS tree is loop-free during the construction of the tree, this method complements the loop detection mechanism provided by the label switched protocol (LDP).

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.

A technique dynamically protects against failure of a head-end node of one or more primary Traffic Engineering Label Switched Paths (TE-LSPs) in a computer network. According to the novel technique, a neighboring upstream node (“protecting node”) of the head-end node learns of the primary TE-LSPs (and their respective state control blocks) extending from the head-end node to one or more address prefixes. The protecting node establishes a repair TE-LSP for each of the primary TE-LSPs to a corresponding downstream neighboring node of the head-end node (a “next-next-hop”). In response to detecting a failure of the head-end node, the protecting node locally reroutes traffic destined for the address prefixes to an appropriate repair TE-LSP. Due to the failure of the head-end node, the protecting node then refreshes the states of the primary TE-LSPs using replicated state control blocks accordingly, until the repair TE-LSPs are no longer needed.

A method of providing at least one restoration path for a primary routing path in a network. The method includes receiving a customer connection request to route information. Costs are assigned for the primary routing path, and the primary routing path is computed based upon the primary routing path costs. A backtracking distance over the primary routing path is determined, and costs for at least one restoration path are assigned. The at least one restoration path may then be computed based upon the at least one restoration path costs.

Source routed multicast LSP is described herein. In one embodiment, when a first node receives a first packet having a label stack including a plurality of labels compatible with MPLS (multi-protocol label switching), in response to a first label on a top of the label stack, the first packet is duplicated into a second packet. In addition, at least two labels are popped from the top of the label stack of the second packet forming a third packet. Thereafter, the first and third packets are processed based on a label on the top of the label stack of the first and third packets respectively. Other methods and apparatuses are also described.

A system, device, and method for establishing and removing a label switched path in a communication network uses a packet-driven mechanism rather than using an explicit signaling protocol to exchange label switching information from an upstream label switching device to a downstream label switching device. In order to establish a label switched path from the upstream label switching device to the downstream label switching device, the upstream label switching device allocates a new label for the label switched path, sets up the label switched path by adding the new label to its forwarding table, and forwards a labeled packet including the new label and an indicator indicating that the packet is labeled. Upon receiving the labeled packet from the upstream label switching device, the downstream label switching device sets up the label switched path by adding the new label to its forwarding table, and forwards the packet based upon network layer addressing information in the packet. In order to remove the label switched path, the upstream label switching device forwards unlabeled packets to the downstream label switching device, and both devices remove the label from its respective forwarding table.

A system for servicing streaming media requests. The system includes stream director nodes and intelligent stream engine nodes, such as permanent storage devices with network interfaces. The stream director node receives a streaming media request and enqueues the request until all resources on a path from the stream engine node having the media object being requested to the user/client system have been reserved. Once reserved, the enqueued request is then serviced by requesting the stream object from the stream engine node, which then transfers the requested stream object between the stream engine node and the user/client system over the prepared path without involving the stream director node. Upon completion, the prepared path is torn down. In one embodiment the prepared path is a Label Switched Path. A provision is made for balancing the load among the stream engine nodes by duplicating stream objects on other stream engine nodes.

A technique protects against failure of a tail-end node of a Traffic Engineering (TE) Label Switched Path (LSP) in a computer network. According to the protection technique, a node along the TE-LSP that is immediately upstream to the protected tail-end node and that is configured to protect the tail-end node (i.e., the “point of local repair” or PLR) learns reachable address prefixes (i.e., “protected prefixes”) of next-hop routers from the tail-end node (i.e., “next-next-hops,” NNHOPs to the protected prefixes from the PLR). The PLR creates a backup tunnel to each NNHOP that excludes the tail-end node, and associates each backup tunnel with one or more protected prefixes accordingly. When the tail-end node fails, Fast Reroute is triggered, and the protected prefix traffic (from the TE-LSP) is rerouted by the PLR onto an appropriate backup tunnel to a corresponding NNHOP. Notably, the PLR performs a penultimate hop popping (PHP) operation prior to forwarding the traffic along the backup tunnel(s).

A method of creating virtual private networks within a packet network having a mesh topology. A flexible virtual private network is established based upon a topology calculated at each member node. The network is set up using label switched paths between adjacent member nodes according to the topology. The topology may be a ring or a tree. A virtual ring is created as a closed-loop sequence of label switched paths established between a set of member nodes. The closed-loop sequence of label switched paths is established by the member nodes as each member node connects to its neighbours on the virtual ring. The virtual ring may expand by adding member nodes and may contract by removing member nodes. A member node's position on the virtual ring may be established using a sortable value.

A label switching routing protocol for establishing a datapath as a sequence of locally unique labels in an optical communications network, is provided. A wavelength on an optical cross-connect is considered as a label, or one portion of a label. Timeslots may be assigned to designated wavelengths so as to form the second portion of a composite label. An optical/time cross-connect (OTXC) capable of wavelength conversion from an input to an output interface creates the datapath based on wavelength to wavelength substitution, under the control of a multi-protocol label switching (MPLS) protocol.

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.

Methods and devices for logically segmenting an LSP so that OAM DTUs may be used to determine the performance and/or the status of LSP segments. To segment a previously determined LSP, a dedicated subpath (a logical LSP) within that predetermined LSP is defined between two LSRs that are capable of processing OAM DTUs. The source node (source LSR) establishes a logical LSP between itself and the destination node (destination LSR) using an LDP. In doing this, the logical LSP traverses a specific path and transits through specific nodes in that path. The source node then transmits an OAM DTU or any other specialized DTU to the destination node using a label specifically associated with the logical LSP that was established. The characteristic of the specific path traversed by the logical LSP can thus be determined by when, how, and if the specialized DTU is received by the destination node.

Traffic engineering using a label-switching protocol is enhanced for label-switched paths that traverse a logical link that is an aggregation of component links. In one embodiment, a label edge router is provided with information regarding the bandwidth capabilities and loading of the component links of a LAG. The label edge router is then allowed to set up paths that traverse a specific component link of a LAG, and reserve bandwidth on such a component link. Other traffic may continue to be distributed across the LAG membership.

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.

The invention relates to an application service message forwarding method and a forwarding node by adopting a multi-protocol label switching (MPLS) technology. The method comprises the following steps that: a forwarding node receives a message; the forwarding node performs the MPLS processing to the received message, wherein when the current node is a Transit in the second hop to last, the original label switching in the message is a virtual label corresponding to a server group; when the current node is an Egress PE, the label in the received message is popped up, wherein the different server groups correspond to the virtual labels of the different server groups; the forwarding node forwards the processed message, wherein the current node is the Egress PE, according to the server group information corresponding to virtual labels of the server groups, the message is forwarded. The method can realize the quick directional forwarding of the content switching.

A communication network is provided having source and destination switching routers connected by two different communication paths. A primary label switched path is established on one of the communication paths and a secondary label switched path is established on the other label switched path. The source switching router can be enabled to place one or more data flows within the primary label switched path and can be enabled to place one or more of the same data flows within the secondary label switched path. The destination switching router stores a label identifying each data flow and a forwarding instruction and can be enabled to reference data carried within the primary or secondary LSP with the appropriate data flow label.

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 technique dynamically triggers an exchange of reachability information between a tail-end (remote) domain target node (e.g., a tail-end node) of a traffic engineering (TE) label switched path (LSP) and a local domain head-end node of the TE-LSP in a computer network. The inter-domain information retrieval technique is illustratively based on triggering a Border Gateway Protocol (BGP) session whereby at least a portion of the reachability, i.e., routing, information of the tail-end node is transmitted to the head-end node of the TE-LSP in accordance with BGP. Specifically, once a TE-LSP is established between the head-end node and the tail-end node, the head-end node triggers the tail-end node, e.g., through extensions to a request/response signaling exchange, to establish the BGP session. Establishment of the BGP session enables transmission of the routing information from the tail-end node to the head-end node. The head-end node uses the routing information to calculate routes, i.e., address prefixes and associated attributes, reachable from the tail-end node for insertion into its routing table.

A method and apparatus for providing point-to-multipoint label switch paths (LSPs) in a Multi-Protocol Label Switching (MPLS) network is described. In one embodiment, a point-to-multipoint LSP is built in a MPLS network by using Resource Reservation Protocol Traffic Engineering (RSVP-TE) to signal the point-to-multipoint LSP as separate point-to-point LSPs and to merge the separate point-to-point LSPs into the point-to-multipoint LSP.

A label switched path may traverse multiple network domains of a communication network, namely, a first MPLS domain and a second MPLS domain interconnected by a non-MPLS domain. The label stack information of a packet sent over the LSP is preserved by establishing an tunnel across the non-MPLS domain of the LSP. The tunnel connects the first MPLS domain and the second MPLS domain of the LSP. The packet and label stack information are encapsulated and sent over the tunnel. An MPLS identifier is included in the header of the encapsulated packet so that the packet and label stack information may be identified at the second MPLS domain.

A system for selectively applying a service to a packet in a network. In a specific embodiment, the system includes a mechanism for encoding service information in a network-compatible packet header and providing encoded data in response thereto. In a more specific embodiment, the network-compatible header includes a Multi-Protocol Label Switching (MPLS) header, a Generic Route Encapsulation (GRE) header, and/or a Layer-2 Tunneling Protocol (L2TP) header.

This invention discloses a ring network and a method for implementing the service thereof. The ring network includes multiple nodes in a same logic layer for accessing a service to the ring network or receiving a service from the ring network; two virtual channels of reverse directions, which connect the adjacent nodes and are utilized to bear and adapt service data; a physical link, which is utilized to bear the service data adapted to the virtual channel. The method includes the steps of configuring virtual channels at the nodes to form an eastward and westward bidirectional ring network; establishing service Label Switching Path schedules at the nodes; determining a service sink node according to the Label Switching Path schedule at a service source node; dispatching services up to the ring network according to a predetermined algorithm; multiplexing the services of different nodes in a same virtual channel for transmission in the way of Label Switching Path; dispatching the services down the ring network at the service sink node.

The invention relates to a telecommunication system, to a local media gateway, to an MSC server, to a radio base station and to a radio network controller for set-up, release and control of local calls in the telecommunication system. The telecommunication system comprises a core network and at least a radio access network (10, 11, 12), an MSC server (18), a central media gateway (MGW) (20) having a point of interconnection to the public switched telecommunication network and at least a radio access gateway (25, 26, 27) to each respective radio access network. A characteristic feature o the invention is that it comprises at least a local MGW (22; 23; 24) provided with switch means and geographically separated from the central MGW. The radio access gateway and the MSC server are provided with control logic for set-up and release of local calls in the respective radio access networks using the local MGW as switch. The local MGW is located in each radio access gateway or in base stations or in a RBS aggregation site connected to a plurality of radio base stations. Thereby the two legs of a local call need not be transported all the way to the MSC. Instead they are interconnected in the local MGW or the RBS aggregation site, thereby reducing costs and trombone effects.

A label switched path is determined in a communications multi-service network comprising a plurality of nodes interconnected via quality of service capable tunnels to provide a QoS guarantee for a session in which resource availability from the network edge to multiple central stages and resource availability from the multiple central stages to the destination edge are established. A series of quality of service capable tunnels is selected by offering a plurality of candidate central stages to the destination edge and allowing the destination edge to select a complete path across the network. A label stack comprising a set of four labels is attached to a payload to define a selected sequence of tunnels.

In this invention, an idea of the reverse direction label switched path (RLP) in Multi-Protocol Label Switching (MPLS) is applied to the multicast transmission to improve the management transmission in the multicast transmission, and to easily carry out an additional connection and disconnection. Specifically, in the reverse direction symmetric routing Label switched Path (LP), a virtual label in addition to an input label and an output label is used for the reverse direction routing. However, in this invention, instead of the virtual label, a multicast address to which a client terminal, which is connected to a head of the path on the reverse direction routing, and corresponds to a leaf in the multicast tree, is connected, is registered, as a multicast index, in routers on the path. Then, when receiving a multicast packet including a label and a multicast address, an output label corresponding to the received label is identified, thereby a destination link is identified.

Virtual private networking methods and systems are disclosed. A label switched path (LSP) is established between network elements which provide access to different autonomous systems (ASs). A record of resources which are used for the LSP is maintained, and a backup LSP is established between the network elements. The backup LSP excludes resources which were used for the LSP. Labeled routes associated with each AS are then redistributed to the network element within the other AS using the LSP or the backup LSP. In another embodiment, VPN labeled routes used by a first network element in a first AS and belonging to a VPN are aggregated into an aggregated inter-AS VPN labeled route, which is distributed to a second AS and redistributed to a second network element, in the second AS, which belongs to the VPN. A data structure for mapping VPN labeled routes to an aggregated inter-AS labeled route is also disclosed.

Provided are a method and apparatus of controlling a Label Switched Path (LSP) of a Resource Reservation Protocol-Traffic Engineering (RSVP-TE) protocol, which may define an available label in an End-to-End range when a label is not changed by transit nodes, and is determined only by an external management system or a manager, or an ingress node or an egress node, thereby more simply and effectively operating the RSVP-TE protocol, and removing limitations in functions of nodes such as path calculating.

An edge router for interfacing an optical label switched core IP network with client networks, which may be electronically switched and operate with different protocol. The core network has a limited number of ports, each with an edge router, which receives packets from one or more associated client networks and queues them according to egress port on the core network and optionally additionally according to attribute of service. When a queue has exceed a maximum packet length or a timeout limit assigned to the queue, the packets including their headers are assembled into a super packet for transmission across the core network in optical form, preferably using optical routers incorporating wavelength conversion of payloads and switching according to an attached label. The edge router at the egress port disassembles the super packet into constituent packets for respective destinations on the client network.

In a packet communications network system, a border gateway protocol is employed to route an information packet from a source in a first autonomous system via a first label switched path to a destination in a second autonomous system via first and second border routers at an interface between the first and second autonomous systems. A label stack attached to the packet identifies both a forwarding interface for the packet and a forwarding behaviour at that interface. This provides a mapping from the first label switched path on to a second label switched path to the destination in the second autonomous system. Preferably, the destination router in the second autonomous system returns to the source router in the first autonomous system a two-label stack identifying first and second paths across the first and second autonomous systems respectively.