Dell Force10 Z9000 FTOS Configuration Guide for Z9000 System - Page 734

www.dell.com | support.dell.com To allocate bandwidth to queues on the C-Series and S-Series, assign each queue a weight ranging from 1 to 1024, in increments of 2n, using the command bandwidth-weight. Table 35-3 shows 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. Note: Dell Force10 recommends assigning bandwidth to all queues. If queues are left un-allocated, the remaining bandwidth is shared equally among the un-allocated queues. If the sum of the allocated bandwidth percentage exceeds 100% 1% from the allocated queues will be assigned to each un-allocated queues. Table 35-3. Default Bandwidth Weights for C-Series and S-Series Queue 0 1 2 3 Default Weight 1 2 4 8 Equivalent Percentage 6.67% 13.33% 26.67% 53.33% There are two key differences between allocating bandwidth by weight on the C-Series and S-Series and allocating bandwidth by percentage on the E-Series: 1. Assigning a weight to one queue affects the amount of bandwidth that is allocated to other queues. Therefore, whenever you are allocating bandwidth to one queue, Dell Force10 recommends that you evaluate your bandwidth requirements for all other queues as well. 2. Because you are required to choose a bandwidth weight in increments of 2n you may not be able to achieve exactly a target bandwidth allocation. Table 35-4 shows an example of choosing bandwidth weights for all four queues to achieve a target bandwidth allocation. Table 35-4. Assigning Bandwidth Weights for the C-Series and S-Series Queue 0 1 2 3 Weight 1 64 128 32 Equivalent Percentage 0.44% 28.44% 56.89% 14.22% Target Allocation 1% 25% 60% 14% Specify WRED drop precedence e z Specify WRED drop precedence is supported only on platform 734 | Quality of Service (QoS)