194 results about "Link-state advertisement" patented technology

A method and system enables policy-based traffic forwarding in a data network by implementing policy-based control over propagation of LSA messages through the data network. A route tag is asserted in respect of a link state advertisement (LSA) message advertising a network address. Propagation of the LSA through the data network is controlled using the asserted internal route tag. At each hop, a policy decision affecting the forwarding of the LSA is made. Exemplary policy decisions include, Pass and Discard. In addition, the forwarding table may be updated using the route and address information contained in the LSA. In this case, routes entered in the forwarding table may be tagged as an inclusion route or an exclusion route. This may be based on the value of an exclusion route flag, which can, for example, be provided as a binary “0” or “1” inserted into an unused portion of the options field of the LSA.

Distributed traffic engineering route exchanger routers (TE-Xs) are used in an open shortest path first (OSPF) routing area to collect Traffic Engineering Link State Advertisements (TE-LSAs) and exchange the TE-LSAs with other TE-Xs. TE-Xs store TE-LSAs and compute explicit routes required by edge routers. A single point of failure that exists when a single centralized TE database is used is thereby eliminated. The TE-Xs peer with other TE-Xs in a routing area and exchange TE-LSAs to keep traffic engineering link state databases (TE-LSDBs) synchronized. Network resources are preserved for payload traffic and resource reservation collisions are reduced.

A novel technique is provided for preventing routing loops by disseminating Border Gateway Protocol (BGP) attribute information in an Open Shortest Path First (OSPF) configured network. Specifically, a new OSPF sub-type-length-value (TLV) is introduced for transporting a conventional BGP autonomous system (AS) path attribute through the OSPF-configured network. Like the BGP AS-path attribute, the new OSPF AS-path sub-TLV is configured to store a set of AS numbers corresponding to the AS path of one or more advertised routes. Thus, when a network device receives an OSPF link-state advertisement (LSA) containing the novel AS-path sub-TLV, the network device determines whether it resides in an autonomous system whose AS number is stored in the sub-TLV. If so, the network device does not install the LSA's advertised routes in its link-state database since the routes, if installed, could result in routing loops.

In a link state protocol such as an interior gateway protocol (IGP), link state advertisements or link state packets (LSA/LSPs) are sent only to network nodes that have expressed interest in them, rather than always flooding them.

The invention includes methods for controlling transmission of a plurality of packets from a sending device to a receiving device. A first method includes determining an expected path for a packet having associated with it a packet size, determining a Media Transmission Unit (MTU) size for the expected path, and, in response to a determination that the packet size is greater than the MTU size, propagating to the sending device a message adapted to reduce packet sizes of subsequent packets to be less than or equal to the MTU size. Other methods include generating a link state advertisement (LSA) for a link including a link TLV having a sub-TVL conveying MTU information associated with the link, transmitting the LSA toward a router, receiving the LSA at the router, and updating a table entry associated with the link using the MTU information conveyed by the sub-TLV.

A link state advertisement protocol message received from an originating device over an inbound interface is forwarded over the fast path according to a reverse path forwarding determination. Specifically, a reverse path forwarding check is performed in order to determine the reverse path forwarding interface for the originating device. A forwarding state that indicates the reverse path forwarding interface may be installed, in which case the forwarding state may be used to determine the reverse path forwarding interface. If the inbound interface is determined to be the reverse path forwarding interface for the originating device, then the link state advertisement protocol message is forwarded over the fast path. Otherwise, the link state advertisement protocol message is not forwarded over the fast path. The link state advertisement protocol message continues to be processed and forwarded by the control plane as usual for robustness.

One embodiment of the present invention provides a system for updating link-status information associated with a prefix in an information-centric network (ICN). During operation, a first node in the ICN receives a link-state advertisement (LSA) message from a neighbor node with the LSA message specifying a prefix and an anchor node advertising the specified prefix. The system determines, based on topology information stored on the first node, whether a shortest-path condition is met, and forwards the received LSA message to other neighbors of the first node in response to the shortest-path condition being met.

A network topology map and a system and method of annotating a network topology map of a packet network is described which monitors traffic engineering extensions in link state advertisement packets. Traffic engineering information contained in traffic engineering extensions is extracted and the traffic engineering information is used to annotate the network topology map with network attributes, such as bandwidth information and traffic engineering metrics.

Each router in a network is configured for executing a link state routing protocol based on outputting a corresponding first link state advertisement message describing a connected link of the router and that specifies a first dynamic routing metric identifying a first cost of the connected link, and a corresponding variation metric identifying a statistical variation of the dynamic routing metric. Each router also is configured for selectively outputting a corresponding second link state advertisement message describing the connected link and that specifies the corresponding variation metric and an updated dynamic routing metric identifying an updated cost of the connected link relative to the first cost, the second link state advertisement message selectively output based on the updated dynamic routing metric differing from the first dynamic routing metric by more than the variation metric, or the router having received another link state advertisement from another router in the network.

A network-connectivity system can receive a remote additive hash for a routing-data collection of a remote network node, and compares the remote additive hash with a local additive hash for a local routing-data collection. A respective additive hash represents one or more network-configuration items of a routing-data collection. Also, at least one of the network-configuration items of the routing-data collection includes reachability information for a network node of a computer network, such as a link-state advertisement. If the system determines that the remote additive hash does not match the local additive hash, the system synchronizes the local routing-data collection with the remote network node of the computer network.

The embodiment of the invention discloses a method for implementing link state database synchronization. The method comprises: receiving link state notifying message; comparing the link state notifying message with that in link state database, updating link state notifying message in the link state database if the received link state notifying message is new message, transmitting the received link state notifying message to virtual neighbor with established virtual neighbor relation. Accordingly, the embodiment of the invention provides a router including circuit board, master control board and standby master control bard. The embodiment of the invention also provides a circuit board and master control board. The embodiment of the invention can simply implement link state database synchronization.

The present invention provides a system, apparatus and method to compute a route through a network having both digital nodes and optical express-thru nodes. According to various embodiments of the invention, a network topology is generated in which both digital nodes, optical express-thru nodes, and optical nodes are identified, and both physical and virtual links between these nodes are mapped. The network connectivity is identified, at least in part, by broadcasting a local link state advertisement and optical carrier group binding information to neighboring nodes, which enables both physical and virtual neighboring nodes to be identified. Once a topology is generated, both physical and virtual link characteristics are analyzed to ensure link diversity for traffic through the network and load balancing functionality across the network.

A method for automatically detecting bi-directional link switched ring link provisioning errors. The method includes receiving an opaque link state advertisement containing bi-directional link switched ring ID and link information at a local node of the ring and checking ring IDs of neighbor nodes of the local node. If the ring IDs of the local node and neighbor nodes do not match a ring ID mismatch alarm is raised.