摘要:
A method of identifying an egress point to a network location in a data communications network comprising a plurality of nodes and links there between comprises the step, performed at the identifying node, of receiving a notification through the network advertising an adjacency to a network location. The method further comprises the steps, performed at the identifying node, of deriving from the notification adjacency information and identifying, from the adjacency information, the egress point.
摘要:
A method of identifying an egress point to a network location in a data communications network comprising a plurality of nodes and links there between comprises the step, performed at the identifying node, of receiving a notification through the network advertising an adjacency to a network location. The method further comprises the steps, performed at the identifying node, of deriving from the notification adjacency information and identifying, from the adjacency information, the egress point.
摘要:
A technique dynamically resizes Traffic Engineering (TE) Label Switched Paths (LSPs) at a head-end node of the TE-LSPs in preparation to receive redirected traffic in response to an event in a computer network. The novel dynamic TE-LSP resizing technique is based on the detection of an event in the network that could cause traffic destined for one or more other (“remote”) head-end nodes of one or more TE-LSPs to be redirected to an event-detecting (“local”) head-end node of one or more TE-LSPs. An example of such a traffic redirection event is failure of a remote head-end node or failure of any of its TE-LSPs. Specifically, the local head-end node maintains TE-LSP steady state sampling and resizing frequencies to adapt the bandwidth of its TE-LSP(s) to gradual changes in the network over time. Upon detection of an event identifying possible traffic redirection, the local head-end node enters a Fast Resize (FR) state, in which the sampling and resizing frequencies are increased to quickly adapt the TE-LSP bandwidth(s) to any received redirected traffic.
摘要:
A local fast reroute (FRR) technique is implemented at the edge of a computer network. In accordance with the technique, if an edge device detects a node or link failure that prevents it from communicating with a neighboring routing domain, the edge device reroutes at least some data packets addressed to that domain to a backup edge device which, in turn, forwards the packets to the neighboring domain. The rerouted packets are designated as being “protected” (i.e., rerouted) data packets before they are forwarded to the backup edge device. The backup edge device identifies protected data packets as those which contain a predetermined “service” label in their MPLS label stacks. In other words, the service label is used as an identifier for packets that have been FRR rerouted. Upon receiving a data packet containing a service label, the backup edge device is not permitted to reroute the packet a second time, e.g., in response to another inter-domain node or link failure, thereby preventing loops from developing at the edge of the network.
摘要:
A fast reroute (FRR) technique that may be deployed at the edge of a network having first and second edge devices coupled to a neighboring routing domain. If the first edge device detects a node or link failure that prevents it from communicating with the neighboring domain, the first edge device reroutes at least some data packets addressed to the neighboring domain to the second edge device. The second edge device receives the rerouted packets and then forwards the packets to the neighboring domain. Notably, the second edge device is not permitted to reroute the received packets a second time, e.g., upon identifying another inter-domain node or link failure. As such, loops are avoided at the edge of the network and packets are rerouted to the neighboring routing domain faster and more efficiently than in prior implementations.
摘要:
A path verification protocol (PVP) which enumerates a series of messages sent to a set of nodes, or routers, along a suspected path identifies forwarding plane problems for effecting changes at the control plane level. The messages include a command requesting interrogation of a further remote node for obtaining information about the path between the node receiving the PVP message and the further remote node. The node receiving the PVP message replies with a command response indicative of the outcome of attempts to reach the further remote node. The series of messages collectively covers a set of important routing points along a path from the originator to the recipient. The aggregate command responses to the series of PVP messages is analyzed to identify not only whether the entire path is operational, but also the location and nature of the problem.
摘要:
In one embodiment, a particular device in a computer network maintains a locally owned tunnel-state table, and joins a distributed hash table (DHT) ring. In addition, the locally owned tunnel-state table is shared with other devices of the DHT ring to establish a DHT-owned tunnel-state table. The particular device (and other devices) determines ownership of link-state advertisements (LSAs) for a specific portion of a traffic engineering database (TED) according to the DHT ring. As such, when the particular device (or any device) computes a path for a tunnel using a local TED, the particular device may request permission to use resources along the computed path that were advertised in particular LSAs from owners of those particular LSAs when not owned by the particular device.
摘要:
A path verification protocol (PVP) which enumerates a series of messages sent to a set of nodes, or routers, along a network path identifies connectivity and transmission characteristic attributes by defining, implementing, and analyzing path verification messages (PVMs) in a VPN environment. Typical VPN environments are characterized by service level agreements (SLAs) between service providers which specify particular service level and/or bandwidth level guarantees, typically in terms of megabits per second (MB/s) or other qualitative transfer criteria. Such guarantees are often expressed in contractual terms as Quality of Service (QoS) criteria. Configurations herein provide a mechanism for determination of paths and/or routes that satisfy a QoS or other delivery speed/bandwidth guarantee. Such a mechanism may therefore be employed to perform routing decisions for QoS based traffic. Further, such a mechanism is employable to verify QoS levels and related attributes related to contractual terms between service providers and customers.
摘要:
A technique efficiently selects a Path Computation Element (PCE) to compute a path between nodes of a computer network. The PCE selection technique is illustratively based on dynamic advertisements of the PCE's available path computation resources, using (i) a low-pass filter algorithm to compute such resources, and (ii) threshold determinations to control distribution of those advertisements. To that end, the novel technique enables one or more PCEs to dynamically send (advertise) their available path computation resources to a Path Computation Client (PCC) by way of the controlled advertisements. In addition, the technique enables the PCC to efficiently select a PCE (or set of PCEs) to service a path computation request based upon those available resources.
摘要:
A data communication device (e.g., a router) originates a network configuration message in response to a network topology change or so as to refresh a configuration message. The data communication device encodes a timestamp in the network configuration message. The timestamp indicates a time of originating the network configuration message. Further, the data communication device transmits the network configuration message over the network to other network devices that, in turn, initiate further broadcast of at least a portion of contents of the network configuration message. Based on the timestamp of the network configuration message, the data communication devices receiving the network configuration message identify transmission time value indicating how long the network configuration message takes to be conveyed over the network to the other network devices. The data communication devices utilize the transmission time value as a timeout period for determining whether a data communication device failure occurs.