Dell PowerSwitch S4820T Configuration Guide for the S4820T System 9.100.0 - Page 677

Creating an Output QoS Policy To create an output QoS policy, use the following commands. 1 Create an output QoS policy. CONFIGURATION mode qos-policy-output 2 After you configure an output QoS policy, do one or more of the following: Scheduler Strict - Policy-based Strict-priority Queueing configuration is done through scheduler strict. It is applied to Qos-policyoutput. When scheduler strict is applied to multiple Queues, high queue number takes precedence. Allocating Bandwidth to Queue Specifying WRED Drop Precedence Configuring Policy-Based Rate Shaping To configure policy-based rate shaping, use the following command. • Configure rate shape egress traffic. QOS-POLICY-OUT mode rate-shape Allocating Bandwidth to Queue The switch schedules packets for egress based on Deficit Round Robin (DRR). This strategy offers a guaranteed data rate. Allocate bandwidth to queues only in terms of percentage in 4-queue and 8-queue systems. The following table shows the default bandwidth percentage for each queue. The following table lists the default bandwidth weights for each queue, and their equivalent percentage which is derived by dividing the bandwidth weight by the sum of all queue weights. Table 70. Default Bandwidth Weights Queue 0 1 2 3 4 5 6 7 Default Bandwidth Percentage for 4- Queue System 6.67% 13.33% 26.67% 53.33% - Default Bandwidth Percentage for 8- Queue System 1% 2% 3% 4% 5% 10% 25% 50% NOTE: The system supports 4 data queues. When you assign a percentage to one queue, note that this change also affects the amount of bandwidth that is allocated to other queues. Therefore, whenever you are allocating bandwidth to one queue, Dell Networking recommends evaluating your bandwidth requirements for all other queues as well. • Assign each queue a bandwidth percentage ranging from 1 to 100%, in increments of 1%. Quality of Service (QoS) 677