Dell S4048T, Configuration Manual

Page: 320 / 1277

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 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 match against the received
application priority. Otherwise, these ports use their locally configured PFC priorities in
application priority TLVs.
• If no configuration source is configured, auto-upstream and auto-downstream ports check to
see that the locally configured PFC priorities match the priorities in a received application
priority TLV.
• On manual ports, an application priority TLV is advertised only if the priorities in the TLV match the
PFC priorities configured on the port.
DCB Configuration Exchange
The DCBx protocol supports the exchange and propagation of configuration information for the enhanced
transmission selection (ETS) and priority-based flow control (PFC) DCB features.
DCBx uses the following methods to exchange DCB configuration parameters:
Asymmetric DCB parameters are exchanged between a DCBx-enabled port and a peer port without
requiring that a peer port and the local port use the same configured values for the
configurations to be compatible. For example, ETS uses an asymmetric exchange of
parameters between DCBx peers.
Symmetric DCB parameters are exchanged between a DCBx-enabled port and a peer port but
requires that each configured parameter value be the same for the configurations in
order to be compatible. For example, PFC uses an symmetric exchange of parameters
between DCBx peers.
Data Center Bridging (DCB) 320