Mutation - Cisco Nexus 7000 Series Configuration Manual

Overview

Mutation

Mutation is the changing of packet header QoS fields. You can map IP precedence, DSCP, or CoS values to
all incoming or outgoing packets. You can use mutation in policies that contain policing commands, but you
cannot use mutation in queuing and scheduling commands. You use configurable, user-defined table maps
for mutation.
Policing
Policing is the monitoring of data rates for a particular class of traffic. The device can also monitor associated
burst sizes.
Three colors, or conditions, are determined by the policer depending on the data rate parameters supplied:
conform (green), exceed (yellow), or violate (red). You can configure only one action for each condition.
When the data rate exceeds the user-supplied values, packets are either marked down or dropped. You can
define single-rate, dual-rate, and color-aware policers.
Single-rate policers monitor the specified committed information rate (CIR) of traffic. Dual-rate policers
monitor both CIR and peak information rate (PIR) of traffic. Color-aware policers assume that traffic has been
previously marked with a color.
Queuing and Scheduling
The queuing and scheduling process allows you to control the bandwidth allocated to traffic classes, so you
achieve the desired trade-off between throughput and latency.
You can apply weighted random early detection (WRED) to a class of traffic, which allows packets to be
dropped based on the CoS field. The WRED algorithm allows you to perform proactive queue management
to avoid traffic congestion.
You can schedule traffic by imposing a maximum data rate on a class of traffic so that excess packets are
retained in a queue to smooth (constrain) the output rate.
Sequencing of QoS Actions
The following are the three types of policies:
• network qos—Defines the characteristics of QoS properties network wide.
• qos—Defines MQC objects that you can use for marking and policing.
• queuing—Defines MQC objects that you can use for queuing and scheduling as well as a limited set of
Note The default type of policy is qos.
The Cisco NX-OS device processes the QoS policies that you define based on whether they are applied to
ingress or egress packets. The system performs actions for QoS policies only if you define them under the
type qos service policies.
the marking objects.
Cisco Nexus 7000 Series NX-OS Quality of Service Configuration Guide
Mutation
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