Configuring A Weight For Wred And Ecn Operation - Dell C9000 Series Networking Configuration Manual

Table 76. Scenarios for WRED and ECN Configuration
Queue Service-Pool
Configuration Configuration
WRED ECN WRED
Disabled Disabled N/A
Enabled Disabled Disabled
Enabled
Enabled Enabled Disabled
Enabled
Configuring a Weight for WRED and ECN
Operation
You can configure a WRED weight to customize WRED and ECN operation on a front-end or backplane
interface. In the configuration procedure, you must also configure the global service-pools of shared buffer
memory that can be accessed by multiple queues when the minimum guaranteed buffers for a queue are
consumed.
1 Configure the weight factor for computation of average-queue size. This weight value applies to front-
end and backplane ports.
QOS-POLICY-OUT mode
Dell(conf-qos-policy-out)#wred weight number
2 Configure one or more WRED profiles, and specify the threshold and maximum drop rate
WRED mode
Dell(conf-wred)#wred thresh-1
Dell(conf-wred)#threshold min 100 max 200 max-drop-rate 40
WRED Threshold
Relationship
Q threshold = Q-T
Service-pool threshold =
SP-T
ECN
N/A N/A
N/A N/A
N/A Q-T < SP-T
SP-T < Q-T
N/A N/A
N/A Q-T < SP-T
SP-T < Q-T
Expected Functionality
WRED/ECN not applicable
Queue-based WRED;
No ECN marking
Service-pool-based WRED;
No ECN marking
Queue-based ECN marking above
queue threshold.
ECN marking up to shared buffer
limits of the service-pool and then
packets are tail dropped.
Same as above but ECN marking
starts above SP-T.
Quality of Service (QoS) 935