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1. Configure the weight factor for the computation of average-queue size. This weight value applies to front-end ports.
QOS-POLICY-OUT mode
DellEMC(conf-qos-policy-out)#wred—profile weight number
2. Configure a WRED profile, and specify the threshold and maximum drop rate.
WRED mode
DellEMC(conf-wred) #wred—profile thresh-1
DellEMC(conf-wred) #threshold min 100 max 200 max-drop-rate 40
3. Configure another WRED profile, and specify the threshold and maximum drop rate.
WRED mode
DellEMC(conf-wred) #wred—profile thresh-2
DellEMC(conf-wred) #threshold min 300 max 400 max-drop-rate 80
4. Associate the service class with the WRED profile, and assign the WRED profile to specific queues on backplane ports.
CONFIGURATION mode
DellEMC(conf) #service-class wred green backplane queue5 thresh-1 queue7 thresh-2
DellEMC(conf) #service-class wred yellow backplane queue1 thresh-2 queue3 thresh-1
DellEMC(conf) #service-class wred weight backplane queue0 11 queue6 4 queue7 9
5. Create a global buffer pool that is a shared buffer pool accessed by multiple queues when the minimum guaranteed buffers
for the queue are consumed.
mode
DellEMC(conf) #service-pool wred green pool0 thresh-1 pool1 thresh-2
DellEMC(conf) #service-pool wred yellow pool0 thresh-3 pool1 thresh-4
DellEMC(conf) #service-pool wred weight pool0 11 pool1 4
6. Attach the ECN marking to specific queues on backplane ports with a service class.
CONFIGURATION mode
DellEMC(conf) #service-class wred ecn backplane 0,3-5,7
7. Create a service class and associate the threshold weight of the shared buffer with each of the queues on backplane.
CONFIGURATION mode
DellEMC(conf)#Service-class buffer shared-threshold-weight backplane queue0 11 queue6 4
queue7 9
8. Create a service class and associate the threshold weight of the shared buffer with each of the queues per port in the
egress direction.
INTERFACE mode
DellEMC(conf-if-te-0/8)#Service-class buffer shared-threshold-weight queue0 11 queue6 4
queue7 9
Pre-Calculating Available QoS CAM Space
Before Dell EMC Networking OS version 7.3.1, there was no way to measure the number of CAM entries a policy-map would
consume (the number of CAM entries that a rule uses is not predictable; from 1 to 16 entries might be used per rule depending
upon its complexity). Therefore, it was possible to apply to an interface a policy-map that requires more entries than are
available. In this case, the system writes as many entries as possible, and then generates an CAM-full error message (shown in
the following example). The partial policy-map configuration might cause unintentional system behavior.
%EX2YD:12 %DIFFSERV-2-DSA_QOS_CAM_INSTALL_FAILED: Not enough space in L3 Cam(PolicyQos)
for class 2 (Te (TeGi 12/20) entries on portpipe 1 for linecard 12 %EX2YD:12
%DIFFSERV-2- DSA_QOS_CAM_INSTALL_FAILED: Not enough space in L3 Cam(PolicyQos) for class
5 (Te 12/ 22) entries on portpipe 1 for linecard 12
%EX2YD:12 %DIFFSERV-2-DSA_QOS_CAM_INSTALL_FAILED: Not enough space in L3
Cam(PolicyQos) for class 2 (TeGi 12/20) entries on portpipe 1
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Quality of Service (QoS)