Telefonaktiebolaget Lm Ericsson (publ)

Enrico Dutti

Giulio Bottari

Stefano Ruffini

Daniele Ceccarelli

Antonio D'Errico

Francesco Fondelli

Riccardo Ceccatelli

Elisa Bellagamba

Silvia Pucci

A method of providing state synchronization between a controller and a switch in a communications network, wherein the controller provides flow data for routing flows through the switch and transmits, in flow modification messages, the flow data to the switch for storage in flow tables, the state synchronization comprising ensuring that flow data in the flow tables of the switch are consistent with the flow data provided by the controller. The method comprises, by the controller (19), providing (21) an identifier in each flow modification message. The method further comprises, upon reestablishment of communications (22) between the controller and the switch after a loss of connectivity receiving (23) a resynchronization message from the switch, wherein the resynchronization message comprises an identifier indication capable of being used to identify an identifier of a most recently received message, determining (24) if all transmitted messages have been received by the switch by comparing the identifier indication with an identifier of a most recently transmitted flow modification message, identifying (25) flow modification messages transmitted after the most recently received message as 'un-received' messages and retransmitting (26) un-received messages.

State synchronization between a controller and a switch in a communications network

A connection-oriented communications network comprises a plurality of interconnected nodes. A traffic path can be set up across the network. Path delay data is obtained for the traffic path by using control plane signalling messages (e.g. a Resource Reservation Protocol-Traffic Engineering, RSVP-TE signalling message) between nodes of the traffic path. The path delay data can be path delay asymmetry data indicative of an asymmetry in path delay between a forward transmission direction and a reverse transmission direction of the traffic path. Each intermediate node along the traffic path can form a signalling message for forwarding to the downstream node which includes one or more values of path delay incurred by that node, or an accumulated path delay value. The path delay can result from one or more of mapping delay, Forward Error Correction (FEC) coding and propagation delay.

Distributing path delay data in a connection-oriented communications network

A method of generating network topology parameters of a communications network domain comprising a plurality of network nodes and a plurality of interconnecting links. The method comprises: identifying network nodes configured to interface with one or more other network domains as summarized nodes; and generating network topology parameters for one or more pairs of summarized nodes. The network topology parameters are dependent on the transmission parameters of one or more identified paths between said pair of summarized nodes. At least one said path comprises at least one other network node and respective interconnecting links.

Generating network topology parameters and monitoring a communications network domain

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Leghorn, Italy

Enrico Dutti