Weighted Random Early Detection; Creating Wred Profiles - Dell S6100 Configuration Manual

Dell(conf-qos-policy-in)#
You will also be able to mark both DSCP and Dot1p in the L3 Input Qos Policy:
Dell(conf)#qos-policy-input qos-input
Dell(conf-qos-policy-in)#set mac-dot1p 2
Dell(conf-qos-policy-in)#set ip-dscp 5
Dell Dell(conf-qos-policy-in)#

Weighted Random Early Detection

Weighted random early detection (WRED) is a congestion avoidance mechanism that drops packets to prevent buffering resources from
being consumed.
The WRED congestion avoidance mechanism drops packets to prevent buffering resources from being consumed.
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 111. Packet Drop Rate for WRED
You can create a custom WRED profile or use one of the five pre-defined profiles.

Creating WRED Profiles

To create WRED profiles, use the following commands.
1 Create a WRED profile.
714 Quality of Service (QoS)