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 system and method are provided for separately distributing edge-device labels and routing information across routing areas of a computer network. Because the edge-device labels are distributed separately from network routing information, the process of distributing the edge-device labels does not preclude conventional edge-device address summarizations. Illustratively, a novel “label mapping” LSA is employed for distributing the edge-device labels across routing areas. The label-mapping LSA may be embodied as an area-scope OSPF opaque LSA (type 10) or an IS-IS LSP containing TLVs of area scope. Advantageously, the present invention is generally applicable whenever label values are allocated to edge devices in a multi-area computer network and data is “tunneled” through the network from one edge device to another.
摘要:
A fast reroute (FRR) technique is implemented at the edge of a computer network. 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 backup edge device is not permitted to reroute the packets a second time. According to the inventive technique, the edge device first identifies a group one or more possible backup edge devices and then selects at least one preferred backup edge device from the group. The edge device makes its selection based on the values of one or more metrics associated with the possible backup edge devices. The metrics are input to a novel selection algorithm that selects the preferred backup edge device(s) using a hierarchical selection process or a weighted-metric selection process, or some combination thereof.
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 is implemented at the edge of a 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. To differentiate which data packets are protected and which are not, the backup edge device employs different sets of VPN label values for protected and non-protected network traffic. That is, the backup edge device may allocate two different VPN label values for at least some destination address prefixes that are reachable through the neighboring domain: a first VPN label value for FRR protected traffic and a second VPN label value for non-protected traffic. Upon receiving a data packet containing a protected VPN label value, 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 technique retrieves computed path segments across one or more domains of a computer network in accordance with a stateful (“semi-stateful”) path computation element (PCE) model. The stateful PCE model includes a data structure configured to store one or more path segments computed by a PCE in response to a path computation request issued by a Path Computation Client (PCC). Notably, each computed path segment stored in the data structure is identified by an associated path-key value (“path key”). The path segment and path key contents of the data structure are temporarily saved (“cached”) at a predetermined location in the network for a configurable period of time.
摘要:
A mechanism to alleviate bandwidth fragmentation in a network employing path computation element(s) to place MPLS Traffic Engineering tunnels. One application is a multiple Autonomous System or multiple area network employing distributed computation of MPLS Traffic Engineering LSPs. A particular path computation element may determine that bandwidth fragmentation is present based on monitoring of path computation failures where desired paths are blocked due to bandwidth constraints. In response to the detected bandwidth fragmentation condition, the path computation element floods a routing notification within its Autonomous System or area. Nodes respond to the routing notification by requesting reoptimization of their own previously requested Traffic Engineering LSPs allowing the path computation element an opportunity to alleviate bandwidth fragmentation.
摘要:
In one embodiment, a network of nodes is configured to communicate according to a configuration of a vertical ladder topology as well as monitoring communication in the network, and/or selectively controls whether or not provisioned particular links will be used. One embodiment colors nodes of the network (e.g., a wireless deterministic network) along different paths through the network and marks packets with the color of each traversed node to track a path taken by a packet. One embodiment sends a particular packet through the network and marks over which links the packet traverses and aggregates these traversed links of other copies of the particular packet. One embodiment controls whether or not the provisioned time slots are used based on flooding a control packet through the network with enable or disable information for each of these links.
摘要:
In one embodiment, a router operating in a hierarchically routed computer network may receive collected data from one or more hierarchically lower devices in the network (e.g., hierarchically lower sensors or routers). The collected data may then be converted to aggregated metadata according to a dynamic schema, and the aggregated metadata is stored at the router. The aggregated metadata may also be transmitted to one or more hierarchically higher routers in the network. Queries may then be served by the router based on the aggregated metadata, accordingly.