A synchronization method of a communication network, the synchronization method comprises monitoring a connection state of second communication nodes that are synchronized using a synchronization signal provided through a first communication node to which a synchronization source is connected, determining whether the number of the connected second communication nodes exceeds a reference value according to a result of the monitoring and switching a synchronization mode of at least one second communication node when the number of the second communication nodes exceeds a reference value.

This disclosure describes methods and systems to for a method for a first computing node to receive frequency information of a system clock. The first computing node receives the frequency information of the system clock from a second computing node at a physical layer of a connection between the first computing node and the second computing node. The first computing node also receives a message from the second computing node at above the physical layer of the connection between the first computing node and the second computing node. The message includes an attestation of the frequency information from which the first computing node may verify that the second computing node is a trusted source of the frequency information.

A distributed Precision Time Protocol (PTP) Transparent Clock (TC) provides a TC function based on overall residence time in a network at a server layer. That is, the server layer operates as a distributed TC for a corresponding client layer. A transport network includes a first node connected to a first client device; and a second node connected to a second client device over a server layer, wherein the first client device communicates to the second client device via a client layer, wherein the first node and the second node are synchronized to one another, and wherein the first node and the second node are configured to implement a distributed transparent clock on a PTP packet at the client layer, the distributed transparent clock includes a correction field in the PTP packet based on a residence time in the transport network at the server layer.

The disclosure relates to a method and device for time-controlled data transmission in a TSN. A new traffic shaping method is described for time-sensitive data streams. The objective is to offer the same real-time performance and configuration complexity as in the prior art but without the need for time synchronization throughout the entire network. The traffic shaper provides that a data frame that is received by a bridge in a first-time interval is passed by this bridge to the next hop/bridge in the next time interval. Each bridge knows the start time of the time interval that belongs to a particular data stream. Each data frame must contain a so-called “delay value,” thus a delay value which is measured by each bridge using a local clock that measures the delay time spent by the data frame in the queue at the outgoing port.

This invention relates to end-to-end transparent clocks and methods of estimating skew in end-to-end transparent clocks. Embodiments of the invention relate to techniques for estimating clock skew between a free-running clock in a transparent clock and a master clock, in particular by using the timing information embedded in timing messages passing through the transparent clock. Further embodiments of the invention set out uses of these estimates to modify the residence times computed by the transparent clock and a synchronization network including such transparent clocks.

Methods, systems, and devices for wireless communications are described. In an example, a method includes a first node receiving a precision time protocol (PTP) message, identifying one or more timing domains to be supported by the first node based at least in part on the PTP message, and sending, to a second node of the wireless communication network, an indicator of the one or more timing domains to be supported by the first node. Another example at a node includes receiving, from additional nodes of the wireless communication network, indicators of one or more timing domains supported by the additional nodes, receiving a PTP message associated with a timing domain, and sending the PTP message to a subset of the additional nodes based at least in a part on the indicators of one or more timing domains supported by the additional nodes.

The forwarding of a management message received in a network device includes determining whether a previously received message sent by the same sender has looped back to the network device. The message is forwarded if the received message is not a loop back of a previously received message, and dropped otherwise.

A network device may assign, to a port of a plurality of ports on the network device, a precision timing protocol (PTP) port priority for PTP communications between the network device and another network device. The network device and the other network device may be communicatively connected via a plurality of links in a link aggregation group (LAG). Each port, of the plurality of ports, may be associated with a respective link, of the plurality of links, in the LAG. The network device may generate a link layer discovery protocol (LLDP) frame that includes information identifying the PTP port priority assigned to the port. The network device may transmit the LLDP frame to the other network device to identify, to the other network device, the PTP port priority.

A relay device accumulates received frames that are not determined as a specific frame in a queue and transfers the frames accumulated in the queue one by one according to a predetermined rule. The relay device transfers a received frame that is determined as a specific frame priority to the frames accumulated in the queue without accumulating the specific frame in the queue.

This invention relates to peer-to-peer transparent clocks and methods of estimating skew in peer-to-peer transparent clocks. Embodiments of the invention relate to techniques for estimating clock skew between a free-running clock in a transparent clock and a master clock, in particular by using the timing information embedded in timing messages passing through the transparent clock. Further embodiments of the invention set out uses of these estimates to modify the residence times computed by the transparent clock and a synchronization network including such transparent clocks.