802.3bd – MAC Control Frame for Priority-based Flow Control
The full title of this PAR is “Standard for Information Technology – Telecommunications and Information Exchange Between Systems – Local and Metropolitan Area Networks – Specific Requirements Part 3: Carrier Sense Multiple Access with Collision Detection (CSMA/CD) Access Method and Physical Layer Specifications – Amendment: MAC Control Frame for Priority-based Flow Control”
This standard defines a MAC Control Frame to support 802.1Qbb Priority-based Flow Control. Data Center Bridging networks (bridges and end nodes) are characterized by limited bandwidth-delay product and limited hop-count. Traffic class is identified by the VLAN tag priority values. Priority-based flow control is intended to eliminate frame loss due to congestion. This is achieved by a mechanism similar to the IEEE 802.3x PAUSE, but operating on individual priorities. This mechanism, in conjunction with other Data Center Bridging technologies, enables support for higher layer protocols that are highly loss sensitive while not affecting the operation of traditional LAN protocols utilizing other priorities. In addition, PFC complements Congestion Notification in Data Center Bridging networks. Operation of priority-based flow control is limited to a domain controlled by a Data Center Bridging control protocol that controls the application of Priority-based Flow Control, Enhanced Transmission Selection, and Congestion Notification.
Data Center Bridging networks employ higher layer protocols that depend on the delivery of data frames without frame loss due to congestion. These protocols were designed for an underlying transport that approaches lossless behavior and therefore do not include appropriate response to frame loss due to congestion (e.g. back-off, slow restart, etc.). This amendment adds the frame format to support 802.1Qbb Priority-based Flow Control.
There is significant customer interest and market opportunity for 802 LANs as a converged Layer 2 solution in high-speed short-range networks such as data centers, backplane fabrics, single and multi-chassis interconnects, computing clusters, and storage networks. These environments currently use Layer 2 networks that do not discard packets due to congestion (e.g., Fibre Channel, InfiniBand). This project will add the frame format to support Priority-based Flow Control which will bring comparable frame loss characteristics to 802 LANs in Data Center Bridging environments. This in conjunction with the IEEE 802.1 Data Center Bridging technologies enable converged networks. Use of a converged network will realize operational and equipment cost benefits.
|Status||PAR approved May 11th, 2009; Standard approved Jun 16th, 2011|
|19 Nov 2009||802.3bd, Draft 0.1|
|01 Dec 2009||802.3bd, Draft 0.3|
|08 Dec 2009||802.3bd, Draft 0.3 -ln|
|19 Jan 2010||802.3bd, Draft 0.3 proposed comment dispositions|
|19 Jan 2010||802.3bd, Draft 0.3 proposed comment dispositions v2|
|20 Jan 2010||802.3bd, Draft 0.3 proposed comment dispositions v3|
|01 Mar 2010||802.3bd.d0, Draft 0 comment dispositions|
|01 Mar 2010||802.3bd, Draft 1.0|
|01 Mar 2010||802.3bd.d0, Draft 1 comment dispositions|
|15 Apr 2010||802.3bd, Draft 2.0|
|25 May 2010||802.3bd.d2, Draft 2 proposed comment dispositions|
|14 Jul 2010||802.3bd, Draft 2.1|
|20 Jul 2010||802.3bd.d2, Draft 2 comment dispositions|
|19 Aug 2010||802.3bd, Draft 2.1 comment dispositions|