Quanta Cloud Technology QuantaMesh QNOS5, Configuration Manual

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Auto-upstream ports that receive internally propagated information ignore their local configuration and
utilize the internally propagated information.
Peer configurations received on auto-upstream ports other than the configuration source result in one of
two possibilities. If the configuration is compatible with the configuration source, then the DCBX client
becomes operationally active on the upstream port. If the configuration is not compatible with the
configuration source, then a message is logged indicating an incompatible configuration, an error counter is
incremented, and the DCBX client is operationally disabled on the port. The expectation is that the network
administrator configures the upstream devices appropriately so that all such devices advertise a compatible
configuration.
A port operating in the auto-downstream role advertises a configuration but is not willing to accept one from
the link partner. However, the port will accept a configuration propagated internally by the configuration
source. Specifically, the willing parameter is disabled on auto-downstream. By default, auto-downstream
ports have the recommendation TLV parameter enabled. Auto-downstream ports that receive internally
propagated information ignore their local configuration and utilize the internally propagated information.
Auto-downstream ports propagate PFC, ETS, and application priority information received from the
configuration source.
In the Configuration Source role, the port has been manually selected to be the configuration source.
Configuration received over this port is propagated to the other auto-configuration ports, however, no
automatic election of a new configuration source port is allowed. Events that cause selection of a new
configuration source are ignored. The configuration received over the configuration source port is
maintained until cleared by the operator (set the port to the manual role).
9.3.3. Configuration Source Port Selection Process
When an auto-upstream or auto-downstream port receives a configuration from a peer, the DCBX client first
checks if there is an active configuration source. If there is a configuration source already selected, the
received configuration is checked against the local port operational values as received from the configuration
source, and if compatible, the client marks the port as operationally enabled. If the configuration received
from the peer is determined to not be compatible, a message is logged, an error counter is incremented
and the DCBX clients become operationally disabled on the port. Operationally disabled means that PFC will
not operate over the port. The port continues to keep link up and exchanges DCBX packets. If a compatible
configuration is later received, the DCBX clients will become operationally enabled.
If there is no configuration source, a port may elect itself as the configuration source on a first-come, first-
serve basis from the set of eligible ports. A port is eligible to become the configuration source if the following
conditions are true:

No other port is the configuration source.

The port role is auto-upstream.

The port is enabled with link up and DCBX enabled.

The port has negotiated a DCBX relationship with the partner.

The switch is capable of supporting the received configuration values, either directly or by
translating the values into an equivalent configuration.
Whether or not the peer configuration is compatible with the configured values is NOT considered.