摘要:
In one embodiment, software code in a respective computer system such as one or more data communication devices establishes multiple layer 2 network links between a first data communication device and a second data communication device. The first data communication device and the second data communication device include corresponding layer 3 interfaces enabling layer 3 network communications over each of the multiple layer 2 network links. The first and second data communication devices route traffic over one (e.g., a primary layer 2 link) of the multiple layer 2 network links using the layer 3 network communications. The private links are media independent. Upon detection of a failure associated with the primary layer 2 link, the data communication devices can automatically switch to sending traffic over a backup link of the multiple layer 2 network links without disrupting publicly advertised routing topology information.
摘要:
Various systems and method for rerouting multicast traffic in response to detecting imminent network disruption are disclosed. One method involves detecting an imminent topology change and, in response, identifying a new multicast distribution tree for a multicast group. A join message for the multicast group is then sent towards a root of the new multicast distribution tree. Multicast traffic addressed to the multicast group continues to be forwarded via the current multicast distribution tree, subsequent to sending the join message. The multicast traffic is not forwarded via the new multicast distribution tree until one or more multicast data packets have been received via the new multicast distribution tree.
摘要:
A method of constructing a backup path in an autonomous system (AS) for failure of an inter-AS link is described. The method comprises identifying an alternate inter-AS path and constructing a tunnel to an end point on the alternate path.
摘要:
A method of constructing a backup path in an autonomous system (AS) for failure of a first inter-AS link serving a first set of prefixes is described. The method comprises identifying an alternate inter-AS link serving said plurality of prefixes and constructing a tunnel thereto.
摘要:
A method is disclosed for constructing a backup route from a source node around an adjacent component. The source node derives a first set of nodes reachable from it without traversing the adjacent component and a second set of nodes from which a neighbor node of adjacent components is reachable without traversing the adjacent component. The source node then constructs a backup route via an intermediate node in the intersection of the first and second sets.
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 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.
摘要:
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.
摘要:
A technique selects a traffic engineering (TE) label switched path (LSP) from among a plurality of TE-LSPs, each of which 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, in order to reach one or more address prefixes within the remote domain. The inter-domain TE-LSP selection technique comprises a selection algorithm executed by the head-end node and based on predetermined TE-LSP attributes (e.g., bandwidth, cost, etc.) and/or address prefix reachability attributes (e.g., cost from a tail-end node to the prefix) to select an appropriate inter-domain TE-LSP for the reachable address prefix. The selection algorithm is embodied in one of two modes: (i) a hierarchical selection mode, or (ii) a weighted selection mode. In addition, the technique comprises a load balancing aspect that cooperates with the selection algorithm to enable the head-end node to balance traffic loads among the multiple TE-LSPs based on the results of the selection algorithm.
摘要:
A technique dynamically retrieves reachability information from a target node, including a tail-end or any intermediate node, along a traffic engineering (TE) label switched path (LSP) that spans multiple domains in a computer network. The interdomain information retrieval technique is illustratively based on a request/response signaling exchange whereby at least a portion of the reachability, i.e., routing, information maintained by the target node is propagated to a head-end node of the TE-LSP. The routing information may comprise a list of address prefixes reachable by the target node, but may optionally include next-hop and metric attributes associated with those prefixes. The head-end node uses the retrieved routing information to calculate routes reachable from the target node for insertion into its routing table.