132 | Data Center Bridging (DCB)w w w . d e l l . c o m | s u p p o r t . d e l l . c o mConfiguring DCBX OperationThe data center bridging exchange protocol (DCBX) is used by DCB devices to exchange configurationinformation with directly connected peers using the link layer discovery protocol (LLDP) protocol. DCBXcan detect the misconfiguration of a peer DCB device, and optionally, configure peer DCB devices withDCB feature settings to ensure consistent operation in a data center network.DCBX is a prerequisite for using DCB features, such as priority-based flow control (PFC) and enhancedtraffic selection (ETS), to exchange link-level configurations in a converged Ethernet environment. DCBXis also deployed in topologies that support lossless operation for FCoE or iSCSI traffic. In these scenarios,all network devices are DCBX-enabled (DCBX is enabled end-to-end). For more information about howthese features are implemented and used on an MXL Switch, refer to:• Configuring Priority-Based Flow Control• Configuring Enhanced Transmission Selection• FIP Snooping• iSCSI OptimizationThe following versions of DCBX are supported on an MXL Switch: CIN, CEE, and IEEE2.5.Prerequisite: DCBX requires the LLDP to be enabled on all DCB devices.DCBX OperationDCBX performs the following operations:• Discovers DCB configuration (such as PFC and ETS) in a peer device.• Detects DCB misconfiguration in a peer device; that is, when DCB features are not compatiblyconfigured on a peer device and the local switch. Misconfiguration detection is feature-specificbecause some DCB features support asymmetric configuration.• Reconfigures a peer device with the DCB configuration from its configuration source if the peerdevice is willing to accept configuration.• Accepts the DCB configuration from a peer if a DCBX port is in “willing” mode to accept a peer’sDCB settings and then internally propagates the received DCB configuration to its peer ports.
