White Papers

Using ETS to Manage Converged Ethernet Traffic
To use ETS for managing converged Ethernet traffic, use the following command:
dcb-map stack-unit all dcb-map-name
Applying DCB Policies in a Switch Stack
You can apply DCB policies with PFC and ETS configurations to all stacked ports in a switch stack or on a stacked switch.
To apply DCB policies in a switch stack, follow this step.
NOTE: Use only 40G ports as stacking ports when you enable DCB. S4820T does not support DCB when you use 10GBaseT
ports as stacking ports.
● Apply the specified DCB policy on all ports of the switch stack or a single stacked switch.
CONFIGURATION mode
dcb-map {stack-unit all | stack-ports all} dcb-map-name
Configure a DCBx Operation
DCB devices use data center bridging exchange protocol (DCBx) to exchange configuration information with directly connected
peers using the link layer discovery protocol (LLDP) protocol.
DCBx can detect the misconfiguration of a peer DCB device, and optionally, configure peer DCB devices with DCB 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 enhanced traffic selection
(ETS), to exchange link-level configurations in a converged Ethernet environment. DCBx is 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 how these features are implemented and used, refer to:
● Configure Enhanced Transmission Selection
DCBx supports the following versions: CIN, CEE, and IEEE2.5.
Prerequisite: For DCBx, enable LLDP on all DCB devices.
DCBx Operation
DCBx performs the following operations:
● Discovers DCB configuration (such as PFC and ETS) in a peer device.
● Detects DCB mis-configuration in a peer device; that is, when DCB features are not compatibly configured on a peer
device and the local switch. Mis-configuration detection is feature-specific because some DCB features support asymmetric
configuration.
● Reconfigures a peer device with the DCB configuration from its configuration source if the peer device is willing to accept
configuration.
● Accepts the DCB configuration from a peer if a DCBx port is in “willing” mode to accept a peer’s DCB settings and then
internally propagates the received DCB configuration to its peer ports.
DCBx Port Roles
To enable the auto-configuration of DCBx-enabled ports and propagate DCB configurations learned from peer DCBx devices
internally to other switch ports, use the following DCBx port roles.
Auto-upstream
The port advertises its own configuration to DCBx peers and is willing to receive peer configuration. The
port also propagates its configuration to other ports on the switch.
Data Center Bridging (DCB) 263