Reference Guide

672 | Quality of Service (QoS)
www.dell.com | support.dell.com
Input QoS policies regulate Layer 3 and Layer 2 ingress traffic. The regulation mechanisms for input QoS
policies are rate policing and setting priority values. There are two types of input QoS policies: Layer 3 and
Layer 2.
• Layer 2 QoS input policies allow you to rate police and set a DSCP or dot1p value.
• Layer 3 QoS input policies allow you to rate police and set a DSCP value.
Output QoS policies regulate egress traffic. The regulation mechanisms for output QoS policies are rate
limiting, rate shaping, and weighted random early detection (WRED).
Create an input QoS policy
To create an input QoS policy:
1. Create a Layer 3 input QoS policy using the
qos-policy-input command from CONFIGURATION
mode. 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:
• Configure policy-based rate policing
• Set a dot1p or DSCP for egress packets
Configure policy-based rate policing
Rate police ingress traffic using the rate-police command from QOS-POLICY-IN mode.
Set a dot1p or DSCP for egress packets
Set a dot1p value for egress packets using the set mac-dot1p command from QOS-POLICY-IN mode.
Create an output QoS policy
To create an output QoS policy:
1. Create an output QoS policy using the
qos-policy-output command from CONFIGURATION mode.
2. After you configure an output QoS policy, do one or more of the following
• Scheduler Strict
• Configure policy-based rate shaping
• Allocate bandwidth to queue
• Specify WRED drop precedence
Note: When changing a "service-queue" configuration 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.