Q-Logic 8100 SERIES 用户手册

1–Product Overview
What is Enhanced Ethernet?

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Standard Ethernet is a best-effort network that may drop packets or deliver 
packets out of order when the network is busy or congested, resulting in 
retransmissions and time-outs. The SCSI payload carried by the Fibre Channel 
protocol does not react well to dropped or out-of-order packets. Therefore, 
standard Ethernet is not an acceptable choice to carry Fibre Channel payloads.

To enable the transport of Fibre Channel frames over Ethernet, several 
enhancements were added to standard Ethernet. These enhancements have 
been ratified in the following IEEE and IETF standards:



Priority flow control (IEEE 802.1Qbb)



Congestion notification (IEEE 802.1Qau)



Link layer routing protocol (IETF–TRILL)



Enhanced transmission selection (802.1Qaz)

Standard Ethernet with these enhancements is known as enhanced Ethernet 
(EE), converged enhanced Ethernet (CEE), lossless Ethernet, or data center 
Ethernet (DCE).

FCoE provides a way to transport Fibre Channel frames on top of an Ethernet 
infrastructure. In summary, unaltered Fibre Channel frames are encapsulated in 
an Ethernet header, sent over a lossless Ethernet fabric, and unencapsulated 
when they reach the target (

). Because protocol conversion tables and 

state tables are not required, FCoE is considered to be a gateway-less 
technology. 

The FCoE architecture is based on the Fibre Channel protocol, and provides the 
same host-to-switch and switch-to-switch connectivity as Fibre Channel fabrics. 
FCoE also provides the same level of management and security found in Fibre 
Channel through the use of zoning and port worldwide name-based port security.