802.1ASbt - Timing and Synchronization: Enhancements and Performance Improvements
The full title of this PAR is "Standard for Local and Metropolitan Area Networks - Timing and Synchronization for Time-Sensitive Applications in Bridged Local Area Networks Amendment: Enhancements and performance improvements".
This amendment specifies enhancements to IEEE Std 802.1AS that are backward compatibile with the features defined in the 2011 version of the standard, including, if necessary, a means of version discovery.
The enhancements that are to be considered by this project include:
- Support for link aggregation (IEEE 802.1AX, IEEE 802.1AXbk, and 802.1AXbq).
- Support for new media types, with corresponding media-dependent layers, e.g., IEEE Std 1901 and WiFi Direct.
- Interoperability with one-step clocks on receive (but with no requirement to generate one-step Sync messages).
- Support for redundant paths.
- Enhancements to the determination of asCapable (e.g., longer cable lengths, new media types).
- Incorporation of the interfaces specified in IEEE Std 802.3bf into the IEEE 802.3 full-duplex media-dependent layer model.
- Improved performance (e.g., improved grandmaster changeover time, longer chains of time-aware systems).
- Carrying information on alternate time scales (e.g., local time for a respective time zone).
- Management support for automatic measurement of link delay asymmetry.
- Additional parameter sets for non-Audio/Video applications, e.g., industrial control.
This amendment allows IEEE 802.1AS to be used: with a greater number of network media types and a greater variety of network configurations, and more effectively with existing and new media types and network configurations.
When development of IEEE Std 802.1AS:2011 began, the main focus was on audio/video (A/V) applications; also, the initial focus was on full-duplex IEEE 802.3 media, and support for IEEE 802.11, IEEE 802.3 EPON, and Coordinated Shared Network media was added during the course of the project. While IEEE 802.1AS:2011 allows effective transport of synchronization over gPTP networks that contain the above media, to support A/V applications, the enhancements described in the scope will allow it to be used more effectively for a greater variety of applications (e.g., embedded applications), and with a greater variety of network media and configurations.
| Status | PAR approved Sep 10th, 2011. Superseded by 802.1AS-Rev |
| Editor | Geoff Garner |
| Date | Document |
|---|---|
| 26 Aug 2013 | 802.1ASbt, Draft 0.1 |
| 30 Oct 2013 | 802.1ASbt, Draft 0.2 |
| 15 Jan 2014 | 802.1ASbt, Draft 0.3 |
| 14 Mar 2014 | 802.1ASbt, Draft 0.4 |
| 03 Jul 2014 | asbt.drafts/2011, Draft cor1/802-1AS-2011-with-cor1-clean |
| 03 Jul 2014 | asbt.drafts/2011, Draft cor1/802-1AS-2011-with-cor1-diff |
| 11 Jul 2014 | 802.1ASbt, Draft 0.5 |
| 13 Jul 2014 | 802.1ASbt, Draft 0.5 |
| 05 Sep 2014 | 802.1ASbt, Draft 0.6 |
| 01 Nov 2014 | 802.1ASbt, Draft 0.7 |
| Date | Document |
|---|---|
| 07 Nov 2011 | Presentation asbt-huang-measurement-of-link-delay-asymmetry-1031-v00.pdf |
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