Dell PowerEdge FN I/O Module Configuration Guide 9.10(0.0)

• If a configuration source already exists, the received peer configuration is checked against the local port configuration. If the received configuration is compatible, the DCBx marks the port as DCBx-enabled. If the configuration received from the peer is not compatible, a warning message is logged and the DCBx frame error counter is incremented. Although DCBx is operationally disabled, the port keeps the peer link up and continues to exchange DCBx packets. If a compatible peer configuration is later received, DCBx is enabled on the port.
• If there is no configuration source, a port may elect itself as the configuration source. A port may become the configuration source if the following conditions exist:
  • 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 performed a DCBx exchange with a DCBx peer.
  • The switch is capable of supporting the received DCB configuration values through either a symmetric or asymmetric parameter exchange.

A newly elected configuration source propagates configuration changes received from a peer to the other auto-configuration ports. Ports receiving auto-configuration information from the configuration source ignore their current settings and use the configuration source information.