Reference Guide

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 108. Packet Drop Rate for WRED
You can create a custom WRED profile or use one of the five pre-defined profiles.
Table 61. Pre-Defined WRED Profiles (
S4820T)
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
2. Specify the minimum and maximum threshold values.
WRED mode
655