A computerized system for performing preparation operations for a maintenance activity that causes a disruption in a communication path of traffic over a multi-layer network. The system comprising: a maintenance tool configured to coordinate maintenance activities of the multi-layer network based on maintenance activity data, a storage unit to store the maintenance activity data; and a multi-layer control system comprising a processor, wherein said processor is configured to: receive from the maintenance tool an indication that one or more maintenance activities are required on an indicated optical resource, determine an affected optical path, determine an affected IP link utilizing said affected optical path; remove traffic from the affected IP link; remove the affected optical path; activate an alternative optical path; configure the packet switching layer to utilize the alternative optical path; and repeat for each affected optical path and each affected IP link.

A network system for a data center is described in which a switch fabric provides interconnectivity such that any servers may communicate packet data to any other of the servers using any of a number of parallel data paths. Moreover, according to the techniques described herein, edge-positioned access nodes, permutation devices and core switches of the switch fabric may be configured and arranged in a way such that the parallel data paths provide single L2/L3 hop, full mesh interconnections between any pairwise combination of the access nodes, even in massive data centers having tens of thousands of servers. The access nodes may be arranged within access node groups, and permutation devices may be used within the access node groups to spray packets across the access node groups prior to injection within the switch fabric, thereby increasing the fanout and scalability of the network system.

A method may include obtaining a topology of an optical network. The topology may indicate multiple optical links within the optical network. The method may also include obtaining a routing metric for each of the optical links. The routing metric may be used in selecting routes through the optical network along the multiple optical links. The method may further include obtaining a signal noise tolerance of an optical signal to be routed through the optical network and adjusting routing metrics of one or more of the multiple optical links based on the signal noise tolerance of the optical signal. The method may also include after the routing metrics of the one or more of the multiple optical links are adjusted, determining a route for the optical signal through the optical network along two or more of the multiple optical links based on the routing metrics of the multiple optical links.

A multi-layer network planning system can determine a set of regenerator sites (“RSs”) that have been found to cover all paths among a set of nodes of an optical layer of a multi-layer network and can determine a set of candidate RSs in the optical layer for use by the links between a set of nodes of an upper layer, wherein each RS can be selected as a candidate RS for the links. The system can determine a binary path matrix for the links between the set of nodes of the upper layer. The system can determine a min-cost matrix that includes a plurality of min-cost paths. The system can determine a best RS from the set of candidate RSs and can move the best RS from the set of candidate RSs into the set of RSs for the links. The system can then update the binary path matrix.

A method of assigning performance indicators to objects of a network employing a computation to assign performance indicators to said objects of said network such that a sum of said performance indicators of objects along a given path in said network in relation to a first threshold value indicates whether said path fulfils a predetermined criterion, and/or indicates whether said path does not fulfil said predetermined criterion.

A method of evaluating a performance of a path in a network based on the performance indicators involves the steps of calculating a sum of performance indicators for said objects along said path and evaluating a performance of said path by comparing said sum against a first threshold value.

The present document discloses a method and a system for restoring an optical layer service. The method includes: determining wavelength resource occupancy information of an inner-link of the node and an optical layer link where the node is located; herein the wavelength resource occupancy information includes resource occupancy state information of a wavelength resource corresponding to a Hold Priority; and flooding the wavelength resource occupancy information in a network where the node is located.

Techniques for virtual private network (VPN) services over optical networks. Client data is received from a source device connected to a first node in an optical communication network. The client data is for transmission over the optical communication network to a destination device connected to a second node in the optical communication network. The client data is transmitted from the source device to the destination device using a layer 2 (L2) virtual network connection between the source device and the destination device. This includes transmitting the client data from the first node to the second node over an optical transport network (OTN) path through the optical communication network using a frame. The second node is configured to receive the frame and transmit the client data to the destination device based on an identifier in the frame.

A content delivery network (CDN) includes: at least one CDN origin node; and multiple CDN cache nodes connected to the at least one CDN origin node via an optical transport network (OTN). Deliveries and/or routing from the multiple CDN cache nodes to the at least one CDN origin node and/or vice versa is performed below layer 3 of the Open Systems Interconnection (OSI) model.

An optically-switch data network includes an optical data bus, an optical wavelength bus, and multiple nodes connected by the optical data bus and the optical wavelength bus. A first node determines that it has communication information to transmit to a second node, and determines if a first subscription signal is present on the optical wavelength bus. The first subscription signal includes a target frequency. If the first subscription signal is not present on the optical wavelength bus, the first node injects an optical communication signal onto the optical data bus. The optical communication signal includes the communication information and a carrier wave. The carrier wave includes the target frequency. The second node receives the optical communication signal using the optical data bus. If the first subscription signal is present on the optical wavelength bus, injection of the optical communication signal onto the optical data bus is postponed.

Techniques for providing closed-loop control and predictive analytics in packet-optical networks are described. For example, an integrated, centralized controller provides tightly-integrated, closed-loop control over switching and routing services and the underling optical transport system of a communication network. In one implementation, the controller includes an analytics engine that applies predictable analytics to real-time status information received from a monitoring subsystem distributed throughout the underlying optical transport system. Responsive to the status information, the analytics engine applies rules to adaptively and proactively identify current or predicted topology-changing events and, responsive to those events, maps reroutes packet flows through a routing/switching network and control and, based on any updated bandwidth requirements due to topology changes, dynamically adjusts allocation and utilization of the optical spectrum and wavelengths within the underlying optical transport system.