Abstract: Interest in multicast group membership may be advertised via a routing system on an Ethernet network along with an indication of an algorithm to be used by the nodes on the network to calculate the distribution tree or trees for the multicast. Each node, upon receipt of the advertisement, will determine the algorithm that is to be used to produce the multicast tree and will use the algorithm to calculate whether it is on a path between nodes advertising common interest in the multicast. Example algorithms may include shortest path algorithms and spanning tree algorithms. This allows multicast membership to be managed via the routing control plane, while enabling spanning tree processes to be used to forward multicast traffic. Since spanning tree is able to install multicast state per service rather than per source per service, this reduces the amount of forwarding state required to implement multicasts on the routed Ethernet mesh network.

Abstract: Interest in multicast group membership may be advertised via a routing system on an Ethernet network along with an indication of an algorithm to be used by the nodes on the network to calculate the distribution tree or trees for the multicast. Each node, upon receipt of the advertisement, will determine the algorithm that is to be used to produce the multicast tree and will use the algorithm to calculate whether it is on a path between nodes advertising common interest in the multicast. Example algorithms may include shortest path algorithms and spanning tree algorithms. This allows multicast membership to be managed via the routing control plane, while enabling spanning tree processes to be used to forward multicast traffic. Since spanning tree is able to install multicast state per service rather than per source per service, this reduces the amount of forwarding state required to implement multicasts on the routed Ethernet mesh network.

Abstract: Interest in multicast group membership may be advertised via a routing system on an Ethernet network along with an indication of an algorithm to be used by the nodes on the network to calculate the distribution tree or trees for the multicast. Each node, upon receipt of the advertisement, will determine the algorithm that is to be used to produce the multicast tree and will use the algorithm to calculate whether it is on a path between nodes advertising common interest in the multicast. Example algorithms may include shortest path algorithms and spanning tree algorithms. This allows multicast membership to be managed via the routing control plane, while enabling spanning tree processes to be used to forward multicast traffic. Since spanning tree is able to install multicast state per service rather than per source per service, this reduces the amount of forwarding state required to implement multicasts on the routed Ethernet mesh network.

Abstract: A system for interfacing a client system in a first network domain with a Provider Link State Bridging (PLSB) domain includes at least two Backbone Edge Bridges (BEBs) of the PLSB domain. Each BEB is an end-point of a connection in the first network domain to the client system and an end-point of at least a unicast path in the PLSB domain. An inter-node trunk is provided in the PLSB domain for interconnecting the BEBs. A phantom node is defined in the PLSB domain and is notionally located on the inter-node trunk. Each of the BEBs is configured such that: an ingress packet received from the client system via the connection in the first network domain is forwarded through a path notionally rooted at the phantom node; and an egress packet destined for the client system is forwarded to the client system through the connection in the first network domain.

Abstract: A consistent tie-breaking decision between equal-cost shortest (lowest cost) paths is achieved by comparing an ordered set of node identifiers for each of a plurality of end-to-end paths. Alternatively, the same results can be achieved, on-the-fly, as a shortest path tree is constructed, by making a selection of an equal-cost path using the node identifiers of the diverging branches of the tree. Both variants allow a consistent selection to be made of equal-cost paths, regardless of where in the network the shortest paths are calculated. This ensures that traffic flow between any two nodes, in both the forward and reverse directions, will always follow the same path through the network.

Abstract: A system for interfacing a client system in a first network domain with a Provider Link State Bridging (PLSB) domain includes at least two Backbone Edge Bridges (BEBs) of the PLSB domain. Each BEB is an end-point of a connection in the first network domain to the client system and an end-point of at least a unicast path in the PLSB domain. An inter-node trunk is provided in the PLSB domain for interconnecting the BEBs. A phantom node is defined in the PLSB domain and is notionally located on the inter-node trunk. Each of the BEBs is configured such that: an ingress packet received from the client system via the connection in the first network domain is forwarded through a path notionally rooted at the phantom node; and an egress packet destined for the client system is forwarded to the client system through the connection in the first network domain.

Abstract: Each equal cost path is assigned a path ID created by concatenating an ordered set of link IDs which form the path through the network. The link IDs are created from the node IDs on either set of the link. The link IDs are sorted from lowest to highest to facilitate ranking of the paths. The low and high ranked paths are selected from this ranked list as the first set of diverse paths through the network. Each of the link IDs on each of the paths is then renamed, for example by inverting either all of the high node IDs or low node IDs. After re-naming the links, new path IDs are created by concatenating an ordered set of renamed link IDs. The paths are then re-ranked and the low and high re-ranked paths are selected from this re-ranked list as the second set of diverse paths.

Abstract: A system for interfacing a client system in a first network domain with a Provider Link State Bridging (PLSB) domain includes at least two Backbone Edge Bridges (BEBs) of the PLSB domain. Each BEB is an end-point of a connection in the first network domain to the client system and an end-point of at least a unicast path in the PLSB domain. An inter-node trunk is provided in the PLSB domain for interconnecting the BEBs. A phantom node is defined in the PLSB domain and is notionally located on the inter-node trunk. Each of the BEBs is configured such that: an ingress packet received from the client system via the connection in the first network domain is forwarded through a path notionally rooted at the phantom node; and an egress packet destined for the client system is forwarded to the client system through the connection in the first network domain.

Abstract: A consistent tie-breaking decision between equal-cost shortest (lowest cost) paths is achieved by comparing an ordered set of node identifiers for each of a plurality of end-to-end paths. Alternatively, the same results can be achieved, on-the-fly, as a shortest path tree is constructed, by making a selection of an equal-cost path using the node identifiers of the diverging branches of the tree. Both variants allow a consistent selection to be made of equal-cost paths, regardless of where in the network the shortest paths are calculated. This ensures that traffic flow between any two nodes, in both the forward and reverse directions, will always follow the same path through the network.

Abstract: Each equal cost path is assigned a path ID created by concatenating an ordered set of link IDs which form the path through the network. The link IDs are created from the node IDs on either set of the link. The link IDs are sorted from lowest to highest to facilitate ranking of the paths. The low and high ranked paths are selected from this ranked list as the first set of diverse paths through the network. Each of the link IDs on each of the paths is then renamed, for example by inverting either all of the high node IDs or low node IDs. After re-naming the links, new path IDs are created by concatenating an ordered set of renamed link IDs. The paths are then re-ranked and the low and high re-ranked paths are selected from this re-ranked list as the second set of diverse paths.

Abstract: A consistent tie-breaking decision between equal-cost shortest (lowest cost) paths is achieved by comparing an ordered set of node identifiers for each of a plurality of end-to-end paths. Alternatively, the same results can be achieved, on-the-fly, as a shortest path tree is constructed, by making a selection of an equal-cost path using the node identifiers of the diverging branches of the tree. Both variants allow a consistent selection to be made of equal-cost paths, regardless of where in the network the shortest paths are calculated. This ensures that traffic flow between any two nodes, in both the forward and reverse directions, will always follow the same path through the network.

Abstract: A method of installing forwarding state in a link state protocol controlled network node having a topology database representing a known topology of the network, and at least two ports for communication with corresponding peers of the network node. A unicast path is computed from the node to a second node in the network, using the topology database, and unicast forwarding state associated with the computed unicast path installed in a filtering database (FDB) of the node. Multicast forwarding state is removed for multicast trees originating at the second node if an unsafe condition is detected. Subsequently, a “safe” indication signal is advertised to each of the peers of the network node. The “safe” indication signal comprises a digest of the topology database. A multicast path is then computed from the network node to at least one destination node of a multicast tree originating at the second node.

Abstract: A method of multicast route computation in a link state protocol controlled network. A spanning tree is computed from a first node to every other node in the network using a known spanning tree protocol. The network is then divided into two or more partitions, each partition encompassing an immediate neighbour node of the first node and any nodes of the network subtending the neighbour node on the spanning tree. Two or more of the partitions are merged when a predetermined criterion is satisfied. Nodes within all of the partitions except a largest one of the partitions are then identified, and each identified node examined to identify node pairs for which a respective shortest path traverses the first node.

Abstract: A consistent tie-breaking decision between equal-cost shortest (lowest cost) paths is achieved by comparing an ordered set of node identifiers for each of a plurality of end-to-end paths. Alternatively, the same results can be achieved, on-the-fly, as a shortest path tree is constructed, by making a selection of an equal-cost path using the node identifiers of the diverging branches of the tree. Both variants allow a consistent selection to be made of equal-cost paths, regardless of where in the network the shortest paths are calculated. This ensures that traffic flow between any two nodes, in both the forward and reverse directions, will always follow the same path through the network.

Abstract: A method of installing forwarding state in a link state protocol controlled network node having a topology database representing a known topology of the network, and at least two ports for communication with corresponding peers of the network node. A unicast path is computed from the node to a second node in the network, using the topology database, and unicast forwarding state associated with the computed unicast path installed in a filtering database (FDB) of the node. Multicast forwarding state is removed for multicast trees originating at the second node if an unsafe condition is detected. Subsequently, a “safe” indication signal is advertised to each of the peers of the network node. The “safe” indication signal comprises a digest of the topology database. A multicast path is then computed from the network node to at least one destination node of a multicast tree originating at the second node.

Abstract: Link bandwidth is varied based on the subscriber traffic load. Varying the link bandwidth has the effect of varying the actual noise margin of the link (in an inverse elation), so that the noise margin will vary inversely with the traffic load. A beneficial result is that, because the noise margin is increased during “off-peak” traffic periods, rapidly varying and burst impairments can be absorbed without causing data loss. In effect, the respective probability distributions of error bursts and traffic load are separated. Data loss only becomes a significant risk when peaks in both distributions coincide. However, the probability of that event occurring is comparatively low. This enables a lower noise margin allocation during design of the link, which dramatically reduces the link cost.

Abstract: A method of multicast route computation in a link state protocol controlled network. A spanning tree is computed from a first node to every other node in the network using a known spanning tree protocol. The network is then divided into two or more partitions, each partition encompassing an immediate neighbor node of the first node and any nodes of the network subtending the neighbor node on the spanning tree. Two or more of the partitions are merged when a predetermined criterion is satisfied. Nodes within all of the partitions except a largest one of the partitions are then identified, and each identified node examined to identify node pairs for which a respective shortest path traverses the first node.

Abstract: Next hop computation functions for use in a per-node ECMP path determination algorithm are provided, which increase traffic spreading between network resources in an equal cost multi-path packet switch network. In one embodiment, packets are mapped to output ports by causing each ECMP node on the network to implement an entropy preserving mapping function keyed with unique key material. The unique key material enables each node to instantiate a respective mapping function from a common function prototype such that a given input will map to a different output on different nodes. Where an output set of the mapping function is larger than the number of candidate output ports, a compression function is used to convert the keyed output of the mapping function to the candidate set of ECMP ports.

Abstract: A system for interfacing a client system in a first network domain with a Provider Link State Bridging (PLSB) domain includes at least two Backbone Edge Bridges (BEBs) of the PLSB domain. Each BEB is an end-point of a connection in the first network domain to the client system and an end-point of at least a unicast path in the PLSB domain. An inter-node trunk is provided in the PLSB domain for interconnecting the BEBs. A phantom node is defined in the PLSB domain and is notionally located on the inter-node trunk. Each of the BEBs is configured such that: an ingress packet received from the client system via the connection in the first network domain is forwarded through a path notionally rooted at the phantom node; and an egress packet destined for the client system is forwarded to the client system through the connection in the first network domain.

Abstract: A method of installing forwarding state in a link state protocol controlled network node having a topology database representing a known topology of the network, and at least two ports for communication with corresponding peers of the network node. A unicast path is computed from the node to a second node in the network, using the topology database, and unicast forwarding state associated with the computed unicast path installed in a filtering database (FDB) of the node. Multicast forwarding state is removed for multicast trees originating at the second node if an unsafe condition is detected. Subsequently, a “safe” indication signal is advertised to each of the peers of the network node. The “safe” indication signal comprises a digest of the topology database. A multicast path is then computed from the network node to at least one destination node of a multicast tree originating at the second node.