Priority Flow Control
Ethernet Flow control disturbs the Ethernet class of service (defined in IEEE 802.1p), as the data of all priorities are stopped to clear the existing buffers which might also consist of low priority data. As a remedy to this problem, Cisco Systems came up with its own priority flow control extension of the standard protocol. This mechanism uses 14 bytes of the 42-byte stuffing in a regular pause frame. The MAC control opcode for a Priority pause frame is 0x0101. Unlike the original pause, Priority pause indicates the pause time in quanta for each of eight priority classes separately. The Priority-based Flow Control (PFC) project was authorized on March 27, 2008 as IEEE 802.1Qbb. Draft 2.3 was proposed on June 7, 2010. Claudio DeSanti of Cisco was editor. The effort was part of the data center bridging task group, which developed Fibre Channel over Ethernet.
Read more about this topic: Ethernet Flow Control, Subsequent Efforts
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