Reference Guide

Data Center Bridging (DCB) | 281
Data Center Bridging Exchange Protocol
The data center bridging exchange (DCBx) protocol is enabled by default on the S5000; PFC and ETS are
also enabled. For more information, see Data Center Bridging: Default Configuration.
DCBx allows a switch to automatically discover DCB-enabled peers and exchange configuration
information. PFC and ETS use DCBx to exchange and negotiate parameters with peer devices. DCBx
capabilities include:
• Discovery of DCB capabilities on peer-device connections
• Determination of a possible mismatch in DCB configuration on a peer link
• Configuration of a peer device over a DCB link
Prerequisite: DCBx requires LLDP to provide the path to exchange DCB parameters with peer devices.
Exchanged parameters are sent in organizationally specific type, length, values (TLVs) in LLDP data units.
For more information, see Chapter 30, Link Layer Discovery Protocol (LLDP).
The following DCBx TLVs are supported for parameter exchange:
• PFC Configuration TLV (for PFC parameters)
• ETS Configuration TLV and ETS Recommendation TLV (for ETS parameters)
• Application Priority Configuration TLV (for FCoE and iSCSI parameters)
Data Center Bridging in a Traffic Flow
Figure 13-3 shows how DCB handles a traffic flow on an interface.
Figure 13-3. DCB PFC and ETS Traffic Handling