Concept Guide

• Layer 3 — QoS input policies allow you to rate police and set a DSCP or dot1p value. In addition, you can congure a drop precedence
for incoming packets based on their DSCP value by using a DSCP color map. For more information, see DSCP Color Maps.
• Layer 2 — QoS input policies allow you to rate police and set a dot1p value.
Output QoS policies regulate egress trac. The regulation mechanisms for output QoS policies are bandwidth percentage, scheduler strict,
rate shaping and WRED.
NOTE: When changing a "service-queue" conguration in a QoS policy map, all QoS rules are deleted and re-added automatically
to ensure that the order of the rules is maintained. As a result, the Matched Packets value shown in the show qos
statistics command is reset.
Creating an Input QoS Policy
To create an input QoS policy, use the following steps.
1 Create a Layer 3 input QoS policy.
CONFIGURATION mode
qos-policy-input
Create a Layer 2 input QoS policy by specifying the keyword layer2 after the qos-policy-input command.
2 After you create an input QoS policy, do one or more of the following:
Conguring Policy-Based Rate Policing
Setting a dot1p Value for Egress Packets
Conguring Policy-Based Rate Policing
To congure policy-based rate policing, use the following command.
• Congure rate police ingress trac.
QOS-POLICY-IN mode
rate-police
Setting a dot1p Value for Egress Packets
To set a dot1p value for egress packets, use the following command.
• Set a dscp or dot1p value for egress packets.
QOS-POLICY-IN mode
set mac-dot1p
Creating an Output QoS Policy
To create an output QoS policy, use the following commands.
1 Create an output QoS policy.
CONFIGURATION mode
qos-policy-output
2 After you congure an output QoS policy, do one or more of the following:
Scheduler Strict — Policy-based Strict-priority Queueing conguration is done through scheduler strict. It is applied to Qos-policy-
output. When scheduler strict is applied to multiple Queues, high queue number takes precedence.
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Quality of Service (QoS)