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NOTE: Because DCBx TLV processing is best effort, it is possible that CIN frames may be processed when DCBx is
configured to operate in CEE mode and vice versa. In this case, the unrecognized TLVs cause the unrecognized TLV
counter to increment, but the frame is processed and is not discarded.
Legacy DCBx (CIN and CEE) supports the DCBx control state machine that is defined to maintain the sequence number and
acknowledge the number sent in the DCBx control TLVs.
DCBx Example
The following figure shows how DCBX is used on an FN IOM Switch installed in a PowerEdge M1000e chassis in which servers
are also installed.
The external 40GbE ports on the base module (ports 33 and 37) of two switches are used for uplinks configured as DCBx
auto-upstream ports. The FN IOM switch is connected to third-party, top-of-rack (ToR) switches through 40GbE uplinks. The
ToR switches are part of a Fibre Channel storage network.
The internal ports (ports 1-32) connected to the 10GbE backplane are configured as auto-downstream ports.
On the FN IOM switch, PFC and ETS use DCBx to exchange link-level configuration with DCBx peer devices.
Figure 142. DCBx Sample Topology
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FC Flex IO Modules