FCoE requirement: Loss-less Ethernet via data center bridging
To deliver storage traffic reliably and in a timely manner, Fibre Channel protocols assume that the underlying fabric is loss-less, even during network congestion. FCoE can use existing 10 Gigabit Ethernet interconnects via the existing IEEE physical pause mechanism.
But new Ethernet extensions, such as priority flow control under the label DCB (Data Center Bridging)-also known as Data Center Ethernet or Converged Enhanced Ethernet-enable logical pause capabilities in order to prioritize traffic types when consolidating I/O. This allows the creation of virtual lanes within an Ethernet link, with each virtual lane assigned a priority level.
During periods of heavy congestion, customers can pause lower-priority traffic while allowing high-priority and latency-sensitive tasks (such as data storage) to continue.