Connectivity Guide

Data center bridging eXchange
DCBX allows a switch to automatically discover and set up DCBX-enabled peers congured with compatible settings. In a converged data
center network, DCBX provides plug-and-play capability for server, storage, and networking devices in an end-to-end solution.
DCBX uses link layer discovery protocol (LLDP) to mediate automatic negotiation and device settings exchange, such as PFC and ETS.
DCBX uses LLDP TLVs to perform DCB parameter exchange:
• PFC conguration and application-priority conguration
• ETS conguration and ETS recommendation
This sample DCBX topology shows two 40GbE ports on a switch that are congured as DCBX auto-upstream ports and used as uplinks to
top-of-rack (ToR) switches. The ToR switches are part of a bre channel storage network.
DCBX conguration notes
• To exchange link-level congurations in a converged network, DCBX is a prerequisite for using DCB features, such as PFC and ETS.
DCBX is also deployed in topologies that support lossless operation for FCoE or iSCSI trac. In these scenarios, all network devices
must be DCBX-enabled so that DCBX is enabled end-to-end.
• DCBX uses LLDP to advertise and automatically negotiate the administrative state and PFC/ETS conguration with directly connected
DCB peers. If you disable LLDP on an interface, DCBX cannot run. Enable LLDP on all DCBX ports,
• DCBX is disabled at a global level by default. Enable DCBX globally on a switch to activate the exchange of DCBX TLV messages with
PFC, ETS, and iSCSI congurations.
• DCBX is enabled by default on OS10 interfaces. You can manually recongure DCBX settings on a per-interface basis. For example, you
can disable DCBX on an interface using the no lldp tlv-select dcbxp command or change the DCBX version using the dcbx
version command.
• For DCBX to be operational, DCBX must be enabled at both the global and interface levels. If the show lldp dcbx interface
command returns the message DCBX feature not enabled, DCBX is not enabled at both levels.
• OS10 supports DCBX versions CEE and IEEE2.5.
• By default, DCBX advertises all TLVs—PFC, ETS Recommendation, ETS Conguration, DCBXP, and basic TLVs.
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Converged data center services