Users Guide

strict-priority
The range is from 1 to 3.
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.
Quality of Service (QoS) 765