Conventions
Refer to the Cisco Technical Tips Conventions for more information on document conventions.
Background Information
The Cisco UCS follows the FCoE protocol as defined by the ANSI T11 Standards Committee. The FC traffic
encapsulated inside this Ethernet requires the same lossless network characteristics that are found in a fabric
network. Instead of the buffer−to−buffer (B2B) credit system used in native fabric topologies, the FCoE relies
on a new set of Ethernet standards that were develop to enhance the Ethernet protocol to ensure lossless
transport of the FCoE traffic.
The Ethernet links on the system support these Ethernet enhancements to ensure lossless transport for the
FCoE traffic:
Priority Flow Control (PFC) IEEE 802.1Qbb is an extension of the PAUSE (802.3x) mechanism. PFC
creates eight virtual links in each physical link and allows any of these links to be paused individually
without affecting the flow of traffic in the other links.
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Enhanced Transmission Selection (ETS) IEEE 802.1Qaz is a scheduling mechanism in hardware that
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