Dell Force10 S4810P Configuration Manual page 830

Allocate bandwidth to queue
The E-Series schedules unicast, multicast, and replication traffic for egress based on the Weighted Fair
Queuing algorithm. The C-Series and S-Series schedule packets for egress based on Deficit Round Robin
(DRR). These strategies both offer a guaranteed data rate.
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 2
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 39-3. Default Bandwidth Weights for C-Series and S-Series
Queue
0
1
2
3
The key difference between allocating bandwidth by weight on the C-Series and S-Series and allocating
bandwidth by percentage on the E-Series because you are required to choose a bandwidth weight in
increments of 2
A key similarity between allocating bandwidth by percentage and allocating by weight is that assigning a
weight or percentage 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.
Table 39-4
bandwidth allocation.
Table 39-4. Assigning Bandwidth Weights for the C-Series and S-Series
Queue
0
1
2
3
830
| Quality of Service (QoS)
, using the command
n
Equivalent
Default Weight Percentage
1 6.67%
2 13.33%
4 26.67%
8 53.33%
you may not be able to achieve exactly a target bandwidth allocation.
n
shows an example of choosing bandwidth weights for all four queues to achieve a target
Equivalent
Weight Percentage
1 0.44%
64 28.44%
128 56.89%
32 14.22%
. Table 39-3
bandwidth-weight
Target
Allocation
1%
25%
60%
14%
shows the default