Converged networks with Fibre Channel over Ethernet and Data Center Bridging

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NOTE
Link Layer Discovery Protocol (LLDP), IEEE 802.1AB, defines a protocol
and a set of managed objects that can be used for discovering the
physical topology and connection end-point information from adjacent
devices in 802 LANs and MANs. The protocol is not restricted from
running on non-802 media.
Table 2. DCBX supported parameters
Protocol Parameters Advertised
PFC
Indication of which priorities have PFC enabled
Willingness to accept PFC recommendations (CNA)
Number of priorities that can support PFC
MACsec bypass capability
ETS Number of traffic classes supported on the port
Priority to Traffic Class Mapping
Willingness to accept ETS recommendations (CNA)
Traffic class bandwidth allocations (for ETS TCs)
Bandwidth allocation algorithms for each TC
QCN
Not currently in the standard
Other
How applications, for example FCoE, map to priorities
Figure 9 illustrates DCBX parameter negotiation between a CNA and the attached switch port where
neither device is willing to accept DCBX parameter recommendations. In this case, the CNA and switch
advertise DCB capabilities to each other. The adapter chooses a storage traffic priority that is not
compatible with the switch. The CNA and switch cannot properly exchange storage traffic with one another
so communication on that link does not happen. Typically, this generates an error that prompts you to
reconfigure either the CNA or the switch parameters to make them compatible. The same situation can
occur on links between switches.