Administrator Guide

Traffic is a mixture of various kinds of packets. The rate at which some types of packets arrive might be greater than others. In this case,
the space on the buffer and traffic manager (BTM) (ingress or egress) can be consumed by only one or a few types of traffic, leaving no
space for other types. You can apply a WRED profile to a policy-map so that specified traffic can be prevented from consuming too much
of the BTM resources.
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 126. Packet Drop Rate for WRED
You can create a custom WRED profile or use one of the five pre-defined profiles.
Table 81. Pre-Defined WRED Profiles
Wred-profile-name min-threshold max-threshold max-drop-rate
wred_drop 0 0 100
wred_teng_y 594 5941 100
wred_teng_g 594 5941 50
wred_fortyg_y 594 5941 50
wred_fortyg_g 594 5941 25
wred_oneg_y_pe 154 1538 100
wred_oneg_g_pe 154 1538 50
wred_teng_y_pe 154 1538 50
wred_teng_g_pe 154 1538 25
Creating WRED Profiles
To create WRED profiles, use the following commands.
1. Create a WRED profile.
CONFIGURATION mode
wred
2. Specify the minimum and maximum threshold values.
WRED mode
756
Quality of Service (QoS)