Congestion Notification Priority Value (CNPV)

A congestion notification priority value (CNPV) is an 802.1p value configured for congestion notification and mapped to the same queue on all ports that make up the congestion notification domain for that CNPV. There are eight 802.1p values from 0 - 7. The maximum number of CNPVs configurable on a 7100-Series port is seven. The maximum number of CNPVs configurable on an S-Series port depends upon the chassis. The SSA, S3, and S4 chassis support a maximum of seven CNPVs. The S6 and S10 chassis support a maximum of four CNPVs. There must always be at least one alternate (non-CNPV) priority value per port.

Use the set dcb cn priority command, specifying the 802.1p priority to set as the CNPV and optionally specifying a creation mode, to create a CNPV for all ports on the device.

By default, a CNPV is created with auto creation enabled when either the creation enable option is specified or no option is specified. “Auto creation enabled” specifies that the port-priority choice mode for each port-priority configured for this CNPV is set to auto and the domain defense mode default is set to edge. See Priority Choice for priority choice details. See Congestion Notification Domain Defense for domain defense mode details.

If creation disable is specified when creating the CNPV, the port-priority choice mode for each port-priority is set to admin and the domain defense mode default is set to interior. Priority choice mode admin uses administratively configured settings when determining the domain defense mode for a port.

Use the set dcb cn priority status command to activate a CNPV on the switch. Congestion notification will not occur for a CNPV unless the CNPV is activated on the switch. CNPVs are active by default. Priority status defaults to enable on creation.