Converged networks with Fibre Channel over Ethernet and Data Center Bridging

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Figure 9. DCBX static parameter exchange
CNA parameters
switch parameters
X
The DCBX protocol’s strength lies in its ability to perform dynamic negotiation using attributes called
recommended and willingness. CNAs and switches using DCBX can advertise their willingness to adopt
parameter settings from their link partner. In the example shown in Figure 10, a CNA communicates the
initial exchange of ETS and PFC information and willingness to consider parameters from the switch. The
switch acknowledges this willingness and sends the CNA the recommended parameter values for ETS and
PFC parameters. If the CNA can successfully adopt the recommended parameters, the CNA will re-
advertise its DCBX parameters using the recommended values. The two devices will then be able to
communicate on the established link.