Administrator Guide

with the new parameter values. When an auto-upstream port (besides the configuration source) receives and
overwrites its configuration with internally propagated information, one of the following actions is taken:
• If the peer configuration received is compatible with the internally propagated port configuration, the link with
the DCBx peer is enabled.
• If the received peer configuration is not compatible with the currently configured port configuration, the link
with the DCBx peer port is disabled and a syslog message for an incompatible configuration is generated. The
network administrator must then reconfigure the peer device so that it advertises a compatible DCB
configuration.
• The configuration received from a DCBx peer or from an internally propagated configuration is not stored
in the switch’s running configuration.
• On a DCBx port in an auto-upstream role, the PFC and application priority TLVs are enabled. ETS
recommend TLVs are disabled and ETS configuration TLVs are enabled.
Auto-downstream The port advertises its own configuration to DCBx peers but is not willing to receive remote peer configuration.
The port always accepts internally propagated configurations from a configuration source. An auto-downstream
port that receives an internally propagated configuration overwrites its local configuration with the new parameter
values.
When an auto-downstream port receives and overwrites its configuration with internally propagated information,
one of the following actions is taken:
• If the peer configuration received is compatible with the internally propagated port configuration, the link with
the DCBx peer is enabled.
• If the received peer configuration is not compatible with the currently configured port configuration, the link
with the DCBx peer port is disabled and a syslog message for an incompatible configuration is generated. The
network administrator must then reconfigure the peer device so that it advertises a compatible DCB
configuration.
• The internally propagated configuration is not stored in the switch's running configuration.
• On a DCBx port in an auto-downstream role, all PFC, application priority, ETS recommend, and ETS
configuration TLVs are enabled.
Configuration
source
The port is configured to serve as a source of configuration information on the switch. Peer DCB configurations
received on the port are propagated to other DCBx auto-configured ports. If the peer configuration is compatible
with a port configuration, DCBx is enabled on the port.
On a configuration-source port, the link with a DCBx peer is enabled when the port receives a DCB configuration
that can be internally propagated to other auto-configured ports. The configuration received from a DCBx peer is
not stored in the switch’s running configuration. On a DCBx port that is the configuration source, all PFC and
application priority TLVs are enabled. ETS recommend TLVs are disabled and ETS configuration TLVs are enabled.
Manual The port is configured to operate only with administrator-configured settings and does not auto-configure with
DCB settings received from a DCBx peer or from an internally propagated configuration from the configuration
source. If you enable DCBx, ports in Manual mode advertise their configurations to peer devices but do not accept
or propagate internal or external configurations. Unlike other user-configured ports, the configuration of DCBx
ports in Manual mode is saved in the running configuration.
On a DCBx port in a manual role, all PFC, application priority, ETS recommend, and ETS configuration TLVs are
enabled.
When making a configuration change to a DCBx port in a Manual role, Dell EMC Networking recommends shutting
down the interface using the shutdown command, change the configuration, then re-activate the interface using
the no shutdown command.
The default for the DCBx port role is manual.
NOTE:
On a DCBx port, application priority TLV advertisements are handled as follows:
• The application priority TLV is transmitted only if the priorities in the advertisement match the configured PFC
priorities on the port.
• On auto-upstream and auto-downstream ports:
• If a configuration source is elected, the ports send an application priority TLV based on the application priority
TLV received on the configuration-source port. When an application priority TLV is received on the configuration-
source port, the auto-upstream and auto-downstream ports use the internally propagated PFC priorities to
Data Center Bridging (DCB) 259