Techniques described herein may be used for determining an offset between clocks in a network. Such techniques may include obtaining, by a passive time device, a first timestamp pair corresponding to a first time protocol message; obtaining, by the passive time device, a second timestamp pair corresponding to a second time protocol message; and calculating, by the passive time device, a clock offset between a time protocol master and the passive time device using the first timestamp pair, the second timestamp pair, and a pre-determined time delay constant corresponding to a network tap.

Provided herein are systems and methods of determining times of events. A server may receive a message from a client in response to an event. The message may identify a first time corresponding to a generation of the event and a second time corresponding to transmission of the message. The first time and the second time may be determined using a first clock of the client. The server may identify, using a second clock of the server, a third time at which the message is received at the server. The server may determine a fourth time based at least on the first time, the second time, and the third time. The fourth time may identify a time according to the second clock at which the event was generated at the client.

Coordinated timing networks are dynamically merged into a single coordinated timing network. This merge occurs without taking down any of the servers. Each server of the merged coordinated timing network has the same coordinated timing network identifier (CTN ID), and the merged coordinated timing network has one selected primary time server. Optionally, the merged coordinated timing network may include a backup time server and an arbiter.

A method for communications is proposed. The method may comprise receiving, by a first network node, a report of clock quality of a second network node from a third network node. A clock of the first network node is selected as a master clock for synchronization in a first timing domain, a clock of the second network node is selected as a is selected as a master clock for synchronization in a second timing domain, and the third network node is attached to at least the first timing domain and the second timing domain. Based at least in part on the received report, it may be determined whether to synchronize the first timing domain to the second timing domain. In response to the determination of synchronizing the first timing domain to the second timing domain, the first network node can obtain timing information of the second network node from the third network node. The method may further comprise tuning the clock of the first network node to synchronize the first timing domain to the second timing domain, based at least in part on the timing information of the second network node.

[Problem to be Solved] Optimizing a route of time synchronization in a network including apparatuses with different types of precision classes. [Solution to the Problem] A time transmission system includes BC nodes 200 with different types of apparatus performances, and multiple routes of PTP packets from GM nodes 101 and 102 to a BC node 220 via the BC node 200 are present. Each BC node 200 located upstream on a route performs notification of performance information indicating its apparatus performance to the BC node 200 located downstream with respect thereto. The BC node 220 includes a determination index calculation unit 11 that calculates a determination index for each route by referencing the performance information notified from the BC nodes 200 located upstream on each route, and a route selection unit 12 that selects a route for transmitting and receiving PTP packets from multiple routes of PTP packets to the BC node 220, based on the calculated determination index for each route.

The present application generally relates to network timing synchronization in the presence of link faults including apparatus and methods In various embodiments, a method includes generating a time synchronization signal, transmitting the time synchronization signal from a first switch to a second switch via a first link and from the first switch to a third switch via a second link, detecting a link failure of the first link, and transmitting the time synchronization signal from the second switch to the third switch via a third link in response to the link failure.

A node may determine the topology of a computation system. The computation system is a network of nodes and multiple nodes are capable of being a grandmaster clock source. The method includes starting a best clock selection process, announcing clock information, and if the node is not acting grand master then receiving messages announcing clock information from other nodes of the network. Topology information is extracted from the messages, and if the node is acting grandmaster then retiring from the position of grandmaster. The best clock selection process steps are repeated until no node of the network becomes acting grandmaster.

A first network device may receive, from a second network device, a clock quality indication that is associated with a clock of the second network device, wherein the clock of the second network device is a reference clock for a network that includes the first network device and the second network device. The first network device may determine, based on a clock signal of the second network device, that a quality metric of the clock does not satisfy a threshold. The first network device may provide, to the second network device, a clock fault notification to cause the second network device to downgrade the clock quality indication transmitted by the second network device. The first network device may select a new reference clock for the first network device based on receiving the downgraded clock quality indication from the second network device.

The present invention discloses a service transmission method, a network device, and a network system. The method includes: obtaining, by a first network device, a client service of FlexE, and obtaining clock information corresponding to the client service; mapping, by the first network device, the client service and the clock information to a timeslot of a FlexE frame, where the client service and the clock information occupy a same timeslot and/or different timeslots; and sending, by the first network device, the FlexE frame to a second network device. Therefore, service clock information can be transparently transmitted in flexible Ethernet by using the method of the present invention.

A Reference Time Scale Dissemination System (RTS-DS) is provided that includes a RTS Dissemination Data Provider (RTS-DDP) and a User Terminal. The RTS Dissemination Data Provider is equipped with a radio receiver designed to receive radio signals and to compute a RTS-DDP Computed Time Scale based on received radio signals. The User Terminal (UT) is equipped with a Radio Receiver designed to receive radio signals and to compute a UT Computed Time Scale based on received radio signals, and with a Clock Device designed to be locked to the UT Computed Time Scale and to provide a UT Local Time Scale resultingly locked to the UT Computed Time Scale. The RTS-DPP is designed to receive a Reference Time Scale, and compute, at a RTS-DDP Computed Time, Time Quantities indicative of a difference between the RTS-DDP Computed Time Scale and the received Reference Time Scale, including a Time Scatter indicative of a difference between the RTS-DDP Computed Time and a corresponding Reference Time, and a Time Offset indicative of a mean value, computed over a timespan, of a number of differences between RTS-DDP Computed Times and corresponding Reference Times.