packets are dropped randomly at an exponential rate until the maximum threshold is reached (as shownin the following illustration); this procedure is the “early detection” part of WRED. If the maximumthreshold, for example, 2000KB, is reached, all incoming packets are dropped until the buffer spaceconsumes less than 2000KB of the specified traffic.Figure 94. Packet Drop Rate for WREDYou can create a custom WRED profile or use one of the five pre-defined profiles.Creating WRED ProfilesTo create WRED profiles, use the following commands.1. Create a WRED profile.CONFIGURATION modewred-profile2. Specify the minimum and maximum threshold values.WRED modethresholdApplying a WRED Profile to TrafficAfter you create a WRED profile, you must specify to which traffic Dell Networking OS should apply theprofile.Dell Networking OS assigns a color (also called drop precedence) — red, yellow, or green — to eachpacket based on it DSCP value before queuing it.DSCP is a 6–bit field. Dell Networking uses the first three bits (LSB) of this field (DP) to determine the dropprecedence.• DP values of 110 and 100, 101 map to yellow; all other values map to green.Quality of Service (QoS) 661
