enhanced transmission selection (802.1Qaz) (ETS)

Error-free data transmission is a crucial prerequisite for the use of Fibre Channel over Ethernet( FCoE), since reliability and fail-safety in storage networks are extremely high and cannot be met by normal Ethernet. Therefore, there are developments for a Lossless Ethernet, which is formed by the Converged Enhanced Ethernet( CEE) and the Data Center Ethernet( DCE), respectively.

To ensure reliability in CEE networks, there are several protocols that fulfill different functions: Priority Flow Control( PFC) is one of them, as well as Enhanced Transmission Selection (ETS), which includes the Data Center Bridging Exchange( DCBX), and Quantized Congestion Notification( QCN). All protocols have been standardized by the IEEE 802.1 working groups (Qbb, Qaz) within the Data Center Bridging( DCB) framework.

While the PFC protocol assigns priorities to networks and users, the ETS protocol takes care of bandwidth management. The ETS protocol assigns bandwidths to the individual networks and users, which can also be combined into groups, according to the priorities. The service with the highest priority also has the highest bandwidth.