IEEE 802.1AS-2011 pdf download IEEE Standard for Local and metropolitan area networks- Timing and Synchronization for Time-Sensitive Applications in Bridged Local Area Networks
3.13 precision: A measure of the deviation from the mean of the time or frequency error between the clockunder test and a perfect reference clock.
3.14 primary reference: A source of time and/or frequency that is traceable to international standards. Seealso. traceability.
3.15 recognized standard source of time: A recognized standard time source is a source external to IEEE1588 precision time protocol (PTP) that provides time that is traceable to the international standards laboratories maintaining clocks that form the basis for the temps atomique international (international atomictime) (TAl) and coordinated universal time (UTC) timescales. Examples of these are National Institute ofStandards and Technology (NIST) timeservers and global posiioning (satellite) system (GPS)
3.16 reference plane: The boundary between a port of a time-aware system and the network physicalmedium. Timestamp events occur as frames cross this interface
3.17 residence time: The duration of the time interval between the receipt of a time synchronization eventmessage by a time-aware system, and the sending of the next subsequent time synchronization eventmessage on another port of that time-aware system. The residence time can be different for different ports.
NOTE_If a port of a time-awaresvstem sends a timme svnchronizationmessage without having received a timesynchronization event message, i.e, if sync receipt timeout occurs (see 10.6.3.1), the duration of the interval between themost recently reccived time synchronization cvent message and the sent time synchronization event mcssage i?matheratically equivalent to residence time: however, this interval is not normally referred to as a residence time.
3.18 stability: A measure of how the mean of the time or frequency error between the clock under test and aperfect reference clock varies with respect to variables such as time, temperature, etc.
3.19 synchronized time: The synchronized time of an event is the time of that event relative to the grand.master,
NOTE-If there is a change in the grandmaster or grandmaster time base, the synchronized time can experience a phascand/or frequency step.
3.20 synchronized time-aware systems: Two time-aware systems are synchronized to a specified uncer.tainty if they have the same epoch and their measurements of the time of a single event at an arbitrary timediffer by no more than that uncertainty.
NOTE-See 8.2.2
3.21 syntonized time-aware systems: Two time-aware systems are syntonized if the duration of the secondis the same on both, which means the time measured by each advances at the same rate. They can but neednot share the same epoch.
3.22 time-aware Bridge: A Bridge that is capable of communicating synchronized time received on oneport to other ports, using the IEEE 802.1AS protocol.
3.23 time-aware end station: An end station that is capable of acting as the source of synchronized time onthe network, or destination of synchronized time using the IEEE 802.1AS protocol, or both.
3,24 time-aware system: A time-aware Bridge or a time-aware end station.
IEEE 802.1AS-2011 pdf download
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