Concept Guide

WRED uses a profile to specify minimum and maximum threshold values. The minimum threshold is the allotted buffer space for
specified traffic, for example, 1000KB on egress. If the 1000KB is consumed, packets are dropped randomly at an exponential
rate until the maximum threshold is reached (as shown in the following illustration); this procedure is the “early detection” part
of WRED. If the maximum threshold, for example, 2000KB, is reached, all incoming packets are dropped until the buffer space
consumes less than 2000KB of the specified traffic.
Figure 104. Packet Drop Rate for WRED
You can create a custom WRED profile or use one of the five pre-defined profiles.
Table 65. Pre-Defined WRED Profiles
Default Profile Name Minimum Threshold Maximum Threshold Maximum Drop Rate
wred_drop 0 0 100
wred_teng_y 467 4671 100
wred_teng_g 467 4671 50
wred_fortyg_y 467 4671 50
wred_fortyg_g 467 4671 25
Creating WRED Profiles
To create WRED profiles, use the following commands.
1. Create a WRED profile.
CONFIGURATION mode
wred-profile
2. Specify the minimum and maximum threshold values.
WRED mode
threshold
Applying a WRED Profile to Traffic
After you create a WRED profile, you must specify to which traffic Dell EMC Networking OS should apply the profile.
Dell EMC Networking OS assigns a color (also called drop precedence) — red, yellow, or green — to each packet based on it
DSCP value before queuing it.
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Quality of Service (QoS)