There is described a Precision Time Protocol (“PTP”) transparent clock for inter-VLAN forwarding comprising a Layer 2 switch and a PTP module. The switch includes a first port associated with a first VLAN and a second port associated with a second VLAN. The switch detects a PTP frame at the first port and the PTP module receives the PTP frame. The switch forwards the PTP frame to the second port in response to the PTP module determining that the PTP frame is a forwardable frame. For another embodiment, the switch includes a ternary content-addressable memory (“TCAM”), and the PTP module configures the TCAM to include forwarding rules. The Layer 2 switch forwards the PTP frame to the second port in response to identifying a particular forwarding rule associated with forwarding the PTP frame.

This technology allows time synchronization in passive optical networks (“PON”). A first Ethernet device timestamps and transmits a packet to a second Ethernet device via the PON. The first Ethernet device transmits the packet to a small form-factor pluggable (“SFP”) device within the PON and connected to the first Ethernet device. The SFP device determines a transmission time to a second SFP device and modifies a correction field (“CF”) of the packet by subtracting an ingress time and the transmission time from the CF. The packet is transmitted to the second SFP device, which modifies the CF by the addition of an egress time. The modified CF value represents the real-time transmission delay incurred in the SFP devices. The packet is transmitted to a second Ethernet device to synchronize a clock using the timestamp and the CF value in accordance with the PTP/IEEE-1588 standard.

Disclosed are a structure and a clock synchronization method of a precision network interface card for acquiring heterogeneous PTP synchronization information for PTP synchronization network extension. In order to precisely time-synchronize a synchronous switch at a remote location with a synchronous switch of an internal network, a precision time protocol (PTP) synchronous network system and a PTP synchronization method according to an embodiment allow a plurality of switches therebetween to operate as virtual nodes and can precisely measure Ingress_Time of a time synchronization message using a clock synchronized with the virtual nodes.

An internal time of a data server is compared against respective times of each of a plurality of devices of a network. The network may require tight time synchronization. The data server utilizes a plurality of high-performance oscillators to maintain the internal time. The data server analyzes the compared times to detect that a time maintained by another device of the network has drifted more than a threshold. An ameliorative action is executed in response to detecting that the time maintained by the another device has drifted more than the threshold.

Systems, methods and devices for low power channel access using a wake up radio are disclosed herein. In accordance with one exemplary embodiment, a method performed by a communication device includes: receiving a wake up signal at a wake up radio from a communication node at a receipt time, wherein the wake up signal indicates a node active time for a main radio to begin communicating with the communication node; determining a transition time between an initiation time for the main radio and a device active time, wherein the device active time is during the node active time; determining a delay time from the receipt time to the initiation time; initiating the main radio at the initiation time; and communicating with the communication node using the main radio during the device active time.

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.

A control plane, available to all of the line cards in a system, is used to exchange time stamps to align the Time of Day counters in the master line cards. The master line cards are locked to a system clock distributed over the backplane by a timing card. The timing card is locked to timing of a slave line card that is synchronized with the grand master. Each master line card synchronizes updating its Time of Day counter based on a time stamp exchange and a local clock locked to the system clock and without the use of a 1 pulse per second signal.

The present invention relates to a wireless network communication technology, and in particular to a time synchronization error compensation method for multi-hop wireless backhaul network based on PTP. Based on PTP, the present invention uses an intermediate node to count the timestamps of transceiving the PTP synchronization message Sync and the delay request message Delay_Req, detect and compensate the local forwarding time of synchronization message Sync and the delay request message Delay_Req and the link delay of transmitting the two between nodes based on the linear regression technology, thereby finally implementing asymmetric delay correction of wireless links between the master and slave nodes and completing time synchronization error compensation. The present invention uses the header of the PTP message to transmit the additional time information about the compensation time, the sending time and arrived time of the message and time correction value without modifying the existing PTP, thereby reducing the message overhead, meeting requirements of real-time and high precision of synchronization error compensation, improving the existing time synchronization precision and having strong practicality.

A method of routing synchronization messages in a packet communication network, in which a packet is routed using a global routing table. A piece of equipment in the network implements the following steps: detecting a packet carrying a synchronization message in a packet stream; determining an output port; emitting a packet carrying the message at the determined output port, the message being modified using a piece of information representing a time of transit in the equipment. A synchronization routing table, which stores at least one association between an input port and at least one output port, is configured in the equipment. When the packet carrying the received message indicates a routing needs to be carried out using the synchronization table, the output port for this packet is determined by the equipment according to an input port on which the packet is received and by reading the synchronization table.

A bridge element is provided for establishing clock synchronization across network elements including a first network element using a first clock synchronization transport protocol and a second network element using a second clock synchronization transport protocol different from the first clock synchronization transport protocol. The bridge element includes a port, a protocol translation port and an interconnect structure. The port may receive a clock synchronization signal from the first network element using the first clock synchronization protocol. The interconnect structure may receive the clock synchronization signal from the port. The protocol translation port may receive the clock synchronization signal from the interconnect structure, translate the clock synchronization signal between the first clock synchronization transport protocol and the second clock synchronization transport protocol, and provide the translated clock synchronization signal to the second network element using the second clock synchronization protocol.