Cisco WS-C3560E-48PD-SF Command Reference - Page 285

Chapter 2 Catalyst 3560 Switch Cisco IOS Commands mls qos queue-set output threshold Usage Guidelines Use the mls qos queue-set output qset-id buffers global configuration command to allocate a fixed number of buffers to the four queues in a queue-set. The drop-threshold percentages can exceed 100 percent and can be up to the maximum (if the maximum threshold exceeds 100 percent). Note The egress queue default settings are suitable for most situations. You should change them only when you have a thorough understanding of the egress queues and if these settings do not meet your QoS solution. The switch uses a buffer allocation scheme to reserve a minimum amount of buffers for each egress queue, to prevent any queue or port from consuming all the buffers and depriving other queues, and to decide whether to grant buffer space to a requesting queue. The switch decides whether the target queue has not consumed more buffers than its reserved amount (under-limit), whether it has consumed all of its maximum buffers (over-limit), and whether the common pool is empty (no free buffers) or not empty (free buffers). If the queue is not over-limit, the switch can allocate buffer space from the reserved pool or from the common pool (if it is not empty). If there are no free buffers in the common pool or if the queue is over-limit, the switch drops the frame. Examples This example shows how to map a port to queue-set 2. It configures the drop thresholds for queue 2 to 40 and 60 percent of the allocated memory, guarantees (reserves) 100 percent of the allocated memory, and configures 200 percent as the maximum memory this queue can have before packets are dropped: Switch(config)# mls qos queue-set output 2 threshold 2 40 60 100 200 Switch(config)# interface gigabitethernet0/1 Switch(config-if)# queue-set 2 You can verify your settings by entering the show mls qos interface [interface-id] buffers or the show mls qos queue-set privileged EXEC command. Related Commands Command mls qos queue-set output buffers queue-set show mls qos interface buffers show mls qos queue-set Description Allocates buffers to a queue-set. Maps a port to a queue-set. Displays QoS information. Displays egress queue settings for the queue-set. 78-16405-05 Catalyst 3560 Switch Command Reference 2-253