A multi-node, quantum communication network for providing quantum-secure time transfer with Damon attack detection is described. The network includes three or more nodes connected via authenticated communication channels forming a closed loop. By determining differences between the local times at as well as the time durations required for photons to travel between the three or more nodes, the network detects a Damon attack, if present. For example, the network imposes a closed loop condition to detect the Damon attack. The network can also use the local time differences and time durations for photon travel between nodes to synchronize the local clocks at the three or more nodes of the network.

A sensor may determine a sampling pattern based on a group of synchronization signals received by the sensor. The sampling pattern may identify an expected time for receiving an upcoming synchronization signal. The sensor may trigger, based on the sampling pattern, a performance of a sensor operation associated with the upcoming synchronization signal. The performance of the sensor operation may be triggered before the upcoming synchronization signal is received.

There are provided a clock node, a controller, a method of operating the clock node and a method of operating the controller in a time distribution network (TDN) comprising the controller being in data communication with the clock nodes via a control path. The method of operating the clock node comprises: sending, from the clock node via the control path to the controller, a first timestamp-related data; receiving, by the clock node via the control path from the controller, clock-recovery control data generated by the controller using the first timestamp-related data received from the clock node; processing the received clock-recovery control data to extract data usable for phase and frequency recovery; and using the extracted data to steer frequency and phase characterizing the clock node.

In one embodiment, a device includes a hardware clock to maintain a clock value, a hardware counter to maintain an estimation of a dynamic error bound of the clock value, and a clock controller to intermittently discipline the hardware clock responsively to a remote clock, advance the hardware counter at a rate responsively to a clock drift, and adjust the hardware counter responsively to the hardware clock being disciplined.

A method establishes an improved clock topology for a computation system, where the computation system is a network of nodes, and where multiple nodes are capable of being a grandmaster clock source. The method includes sequentially selecting each selectable node as an acting grandmaster node, the acting grandmaster node sending announce messages, each node with a determinative communication requirement extracting topology information from the announce messages. The above steps are repeated with another node until each selectable node has been an acting grandmaster. The method then includes selecting the clock source based on the best clock topology for the set of nodes with determinative communication requirements.

Provided are a clock synchronization method performed between communication nodes included in a communication network, the clock synchronization method comprises receiving a synchronization source signal through any one of remaining communication nodes except for an uppermost communication node included in the communication network, generating a reference clock for clock synchronization from the received synchronization source signal and transmitting the generated reference clock through a first path including at least a portion reverse to a second path through which a downlink signal is transmitted in the communication network.

The time synchronization of a network is protected against unauthorized changes to the grandmaster clock of a base time domain by monitoring the physical communication interfaces of a network device for arrival of messages relating to time synchronization. If the messages relating to time synchronization apply to the initially set-up and synchronized base time domain, a check is performed to determine whether the messages relating to time synchronization announce a new grandmaster clock having better clock parameters than those of the present grandmaster clock. If so, a virtual base time domain is started by the network device. If the verification reveals that the proposed new grandmaster clock is trustworthy or valid, the network device discontinues the virtual time domain, updates its stored information concerning the grandmaster clock and, from this time onward, sends messages relating to time synchronization that are based on the new clock parameters to the network.

Systems and methods include receiving Interior Gateway Protocol (IGP) messages from one or more network elements in a network; extracting timing information from any of the IGP messages where the timing information includes timing reference for a given network element for any of frequency, phase, and time; and storing the timing information. The steps can further include one of displaying a Graphical User Interface of the network including an operational timing trail for any of frequency, phase, and time; and displaying the timing information for the one or more network elements via a Command Line Interface (CLI).

In a network having at least one slave node including a slave clock, a method of adjusting the slave clock relative to a master clock of a master node includes, at the slave node, correcting a time of day of the slave clock using (a) a slave pulse signal having a known slave pulse rate, (b) a time-of-day counter of the slave node, and (c) a master pulse signal, based on values of the slave clock at nearest corresponding edges of the slave pulse signal and the master pulse signal, and correcting a frequency of the slave clock using the slave pulse signal, a clock signal of the slave node, and the master pulse signal, based on values of the slave clock at nearest corresponding edges of the master pulse signal. No other clock signal from outside the slave node is used for the corrections.

The disclosure relates to a method for determining a master clock in a communication network having a plurality of stations that are communicatively connected to each other and each have a clock, wherein the master clock is used for time synchronization of the clocks of the stations, comprising the steps: determining by means of a model of the communication network, a synchronization path measure for each station to every other station of the stations, which specifies a synchronization accuracy between two stations; determining for each station on the basis of the synchronization path measure in each case a synchronization metric, which specifies a synchronization accuracy for this station; and determining on the basis of the synchronization metrics of all the stations the station whose clock is meant to be used as the master clock.