Dcbx Feature Negotiation - Cisco AP775A - Nexus Converged Network Switch 5010 Configuration Manual

DCBX Feature Negotiation

• CIN-DCBX—The Cisco, Intel, Nuova DCBX is supported on Gen-1 converged network adapters
DCBX runs on the physical Ethernet link between the Cisco Nexus 5000 Series switch and the CNA. By
default, DCBX is enabled on Ethernet interfaces. When an Ethernet interface is brought up, the switch
automatically starts to communicate with the CNA.
During the normal operation of FCoE between the switch and the CNA, DCBX provides link-error detection.
DCBX is also used to negotiate capabilities between the switch and the CNA and to send configuration values
to the CNA.
The CNAs that are connected to a Cisco Nexus 5000 Series switch are programmed to accept the configuration
values sent by the switch, allowing the switch to distribute configuration values to all attached CNAs, which
reduces the possibility of configuration errors and simplifies CNA administration.
DCBX Feature Negotiation
The switch and CNA exchange capability information and configuration values. The Cisco Nexus 5000 Series
switches support the following capabilities:
• FCoE—If the CNA supports FCoE capability, the switch sends the IEEE 802.1p CoS value to be used
• Priority Flow Control (PFC)—If the adapter supports PFC, the switch sends the IEEE 802.1p CoS values
• Priority group type-length-value (TLV)
• Ethernet logical link up and down signal
• FCoE logical link up and down signal for pre-FIP CNAs
The following rules determine whether the negotiation results in a capability being enabled:
• If a capability and its configuration values match between the switch and the CNA, the feature is enabled.
• If a capability matches, but the configuration values do not match, the following occurs:
• If the CNA does not support a DCBX capability, that capability remains disabled.
• If the CNA does not implement DCBX, all capabilities remain disabled.
The Cisco Nexus 5000 Series switch provides CLI commands to manually override the results of the PFC
Note
negotiation with the adapter. On a per-interface basis, you can force capabilities to be enabled or disabled.
Cisco Nexus 5000 Series Switch CLI Software Configuration Guide
396
(CNAs). CIN-DCBX is used to perform link detection in addition to other functions.
with FCoE packets.
to be enabled with PFC.
◦ If the CNA is configured to accept the switch configuration value, the capability is enabled using
the switch value.
◦ If the CNA is not configured to accept the switch configuration value, the capability remains
disabled.
Information About FCoE
OL-16597-01