Dell PowerSwitch S4820T 9.50.1 Configuration Guide for the S4820T System - Page 277

queues drain out, the remaining data traffic is scheduled to queues according to the bandwidth and scheduler configuration in the DCB output policy. The available bandwidth (that the ETS algorithm calculates) is equal to the link bandwidth after scheduling non-ETS higher-priority traffic. The configuration of bandwidth allocation and strict-queue scheduling is not supported at the same time for a priority group. If both are configured, the configured bandwidth allocation is ignored for prioritygroup traffic when you apply the output policy on an interface (refer to Applying an ETS Output Policy for a Priority Group to an Interface). Bandwidth assignment in a dot.1p priority-queue: By default, equal bandwidth is assigned to each port queue and each dot1p priority in a priority group. To configure bandwidth amounts in associated dot1p queues, use the bandwidth-percentage command. When specified bandwidth is assigned to some port queues and not to others, the remaining bandwidth (100% minus assigned bandwidth amount) is equally distributed to unassigned nonstrict priority queues in the priority group. The sum of the allocated bandwidth to all queues in a priority group should be 100% of the bandwidth on the link. Bandwidth assignment in a priority group: By default, equal bandwidth is assigned to each priority group in the DCB output policy applied to an egress port if you did not configure bandwidth allocation. The sum of configured bandwidth allocation to dot1p priority traffic in all ETS priority groups must be 100%. Allocate at least 1% of the total bandwidth to each priority group and queue. If you assign bandwidth to some priority groups but not to others, the remaining bandwidth (100% minus assigned bandwidth amount) is equally distributed to non strict-priority groups which have no configured scheduler. Scheduling of priority traffic: dot1p priority traffic on the switch is scheduled to the current queue mapping. dot1p priorities within the same queue should have the same traffic properties and scheduling method. DCB output-policy error: If an error occurs in an DCB output-policy configuration, the configuration is ignored and the scheduler and bandwidth allocation settings are reset to the ETS default values (all priorities are in the same ETS priority group and bandwidth is allocated equally to each priority). If an error occurs when a port receives a peer's ETS configuration, the port's configuration is reset to the previously configured DCB output policy. If no DCB output policy was previously applied, the port is reset to the default ETS parameters. Creating an ETS Priority Group An ETS priority group specifies the range of 802.1p priority traffic to which a QoS output policy with ETS settings is applied on an egress interface. You can associate a priority group to more than one ETS output policy on different interfaces. 1. Create an ETS priority group to use with an ETS output policy. CONFIGURATION mode priority-group group-name The maximum is 32 characters. 2. Configure the priority-group identifier. PRIORITY-GROUP mode set-pgid value Data Center Bridging (DCB) 277