Administrator Guide

Enabling Strict-Priority Queueing
Strict-priority means that Dell Networking OS de-queues all packets from the assigned queue before servicing any other queues.
● The strict-priority supersedes bandwidth-percentage configuration.
● A queue with strict priority can starve other queues in the same port-pipe.
● Assign strict priority to one unicast queue.
CONFIGURATION mode
strict-priority
The range is from 1 to 3.
Weighted Random Early Detection
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 96. 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.
CONFIGURATION mode
wred-profile
2. Specify the minimum and maximum threshold values.
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Quality of Service (QoS)