Administrator Guide

As a result, lossless traffic is ensured only if traffic ingresses on a PFC-enabled port and egresses on another
PFC-enabled port.
Lossless traffic is not guaranteed when it is transmitted on a PFC-enabled port and received on a link-level
flow control-enabled port, or transmitted on a link-level flow control-enabled port and received on a PFC-
enabled port.
Enabling DCB on Next Reload To configure the Aggregator so that all interfaces come up with DCB enabled
and flow control disabled, use the dcb enable on-next-reload command. Internal PFC buffers are
automatically configured.
1 Globally enable DCB on all interfaces after next switch reload.
CONFIGURATION mode
dcb enable on-next-reload
To reconfigure the Aggregator so that all interfaces come up with DCB disabled and link-level flow control
enabled, use the no dcb enable on-next-reload command. PFC buffer memory is automatically freed.
Enabling Auto-DCB-Enable Mode on Next Reload To configure the Aggregator so that all interfaces come
up in auto-DCB-enable mode with DCB disabled and flow control enabled, use the dcb enable aut-
detect on-next-reload command.
1 Globally enable auto-detection of DCBx and auto-enabling of DCB on all interfaces after switch reload.
CONFIGURATION mode
dcb enable auto-detect on-next-reload
Enabling DCB To configure the Aggregator so that all interfaces are DCB enabled and flow control disabled,
use the dcb enable command.
Disabling DCB To configure the Aggregator so that all interfaces are DCB disabled and flow control enabled,
use the no dcb enable command.
dcb enable auto-detect on-next-reload Command Example
Dell#dcb enable auto-detect on-next-reload
Configuring Priority-Based Flow
Control
PFC provides a flow control mechanism based on the 802.1p priorities in converged Ethernet traffic received
on an interface and is enabled by default when you enable DCB.
As an enhancement to the existing Ethernet pause mechanism, PFC stops traffic transmission for specified
priorities (Class of Service (CoS) values) without impacting other priority classes. Different traffic types are
assigned to different priority classes.
When traffic congestion occurs, PFC sends a pause frame to a peer device with the CoS priority values of the
traffic that is to be stopped. Data Center Bridging Exchange protocol (DCBx) provides the link-level exchange
Data Center Bridging (DCB) 284