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Data center bridging

Data center bridging (DCB) is a collection of extensions to the existing Ethernet standard that provides a lossless transport layer for FCoE, iSCSI, and other NIC traffic sharing the same physical CNA interface. DCB assigns priority and allocates bandwidth to network traffic based on the traffic protocol.

The DCB standard resolves packet loss issues by implementing the following technologies:
Per-priority pause (priority-based flow control)
Enables a device to only inhibit the transmission of frames based on user-defined priorities.
Enhanced transmission selection
Allows administrators to allocate bandwidth on a percentage basis to different priorities.
Congestion notification
Transmits congestion information.
DCB Exchange (DCBX) protocol
Exchanges connection information with directly connected peers and detects misconfigurations.

Although these technologies possess their own independent functions, they operate together to provide an enhanced Ethernet standard that eliminates packet loss due to traffic congestion. For more information about FCoE deployment, see TR-3800.

Note: iSCSI DCB support is only available on the QLogic 8300 series dual port 10GbE CNA adapter.