Note: The Audio/Video Bridging Task Group was renamed the "Time-Sensitive Networking Task Group" in November, 2012. Please refer to that page for further information. The rest of this page has been preserved it existed at that time, without some obsolete meeting information.
The charter of the TG is to provide the specifications that will allow time-synchronized low latency streaming services through 802 networks. Specific goals include:
- A Layer 2 time synchronizing service that is appropriate for the most stringent requirements of consumer electronics applications. This was done in cooperation with the IEEE 1588 working group, and so the point-to-point 802.3 sublayer of 802.1AS is a specific profile of IEEE Std 1588-2008. The original version of this work has been published as "IEEE Std 802.1AS-2011: IEEE Standard for Local and Metropolitan Area Networks - Timing and Synchronization for Time-Sensitive Applications in Bridged Local Area Networks", is currently under revision as "IEEE P802.1ASbt: IEEE Standard for Local and Metropolitan Area Networks - Timing and Synchronization for Time-Sensitive Applications in Bridged Local Area Networks"and the PAR and 5 Critera are available in the public archives.
- Definition of an admission control system that allows bridges to guarantee the resources needed for AV streams. The original version of this work has been published as "IEEE Std 802.1Qat-2010: IEEE Standard for Local and Metropolitan Area Networks---Virtual Bridged Local Area Networks - Amendment: 11: Stream Reservation Protocol (SRP)". New work to provide multiple paths for both redundancy and enhanced network throughput is currently being examined.
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Enhancement of standard 802.1 bridge frame forwarding rules to support AV streams. The original version of this work has been published as "IEEE Std 802.1Qav-2010: IEEE Standard for Local and Metropolitan Area Networks---Virtual Bridged Local Area Networks - Amendment 12: Forwarding and Queuing Enhancements for Time-Sensitive Streams". Two new projects are under way to provide even lower network delays:
- Support for packet preemption, which allows very time-sensitive packets to interrupt a normal best-effort packet being transmitted on an egress port and then resume it once the time-sensitive packet has been transmitted. This work is being done as "project P802.1Qbu: Standard for Local and metropolitan area networks--Media Access Control (MAC) Bridges and Virtual Bridged Local Area Networks Amendment: Frame Preemption" and the current PAR and 5 criteria are available in the public archives.
- Scheduled traffic enhancements, which defines ways for bridges and end stations to schedule the transmission of frames based on timing derived from IEEE Std 802.1AS. This work is being done as "project P802.1Qbv: Standard for Local and metropolitan area networks--Media Access Control (MAC) Bridges and Virtual Bridged Local Area Networks Amendment: Enhancements for Scheduled Traffic" and the current PAR and 5 criteria are available in the public archives.
- Establishment of a set of usage-specific profiles that will help ensure interoperability between networked devices using the AV bridging specifications. The original version of this work has been published as "IEEE Std 802.1BA-2011 : Standard for Local and Metropolitan Area Networks: Audio Video Bridging (AVB) Systems". A project to amend this standard will be started once the other new AVB projects are complete..
All participants should keep up to date on the current "assumptions" document since it includes much of the background information on technical approaches and work that needs to be done.
The original work on AV bridging was done as part of the "Residential Ethernet Study Group" of 802.3
Active projects:
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P802.1ASbt: IEEE Standard for Local and Metropolitan Area Networks - Timing and Synchronization for Time-Sensitive Applications in Bridged Local Area Networks
- Status: PAR approved, technical development just starting
- P802.1Qbu: Standard for Local and metropolitan area networks--Media Access Control (MAC) Bridges and Virtual Bridged Local Area Networks Amendment: Frame Preemption
- Status: PAR in development
- P802.1Qbv: Standard for Local and metropolitan area networks--Media Access Control (MAC) Bridges and Virtual Bridged Local Area Networks Amendment: Enhancements for Scheduled Traffic
- Status: PAR in development
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