Priority Flow Control
Ethernet protocol provides no guarantees for traffic delivery. If any Ethernet frame carrying data is dropped, it is up to the higher-level protocols, such as TCP, to retransmit the lost portions. PFC provides lossless Ethernet transport services for FCoE traffic, which are essential because Fibre Channel frames encapsulated within FCoE packets expect lossless fabric behavior. Ethernet defines the flow control mechanism under the IEEE 802.3X standard in which flow control operates on the entire physical link level, and it cannot differentiate between different types of traffic forwarded through the link; that is, pausing either all or none of them. When such per-physical link PAUSE frames are triggered, they indiscriminately ...
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