General Qos Guidelines; Enabling Qos Globally; Configuring Classification Using Port Trust States; Configuring The Trust State On Ports Within The Qos Domain - Cisco Catalyst 2975 Software Configuration Manual

Chapter 33 Configuring QoS

General QoS Guidelines

These are general QoS guidelines:
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Enabling QoS Globally

By default, QoS is disabled on the switch.
Beginning in privileged EXEC mode, follow these steps to enable QoS. This procedure is required.
Command
Step 1
configure terminal
Step 2 mls qos
Step 3 end
Step 4 show mls qos
Step 5 copy running-config startup-config
To disable QoS, use the no mls qos global configuration command.

Configuring Classification Using Port Trust States

These sections describe how to classify incoming traffic by using port trust states. Depending on your
network configuration, you must perform one or more of these tasks or one or more of the tasks in the
"Configuring a QoS Policy" section on page
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Configuring the Trust State on Ports within the QoS Domain

Packets entering a QoS domain are classified at the edge of the QoS domain. When the packets are
classified at the edge, the switch port within the QoS domain can be configured to one of the trusted
states because there is no need to classify the packets at every switch within the QoS domain.
Figure 33-10
OL-19720-02
Control traffic (such as spanning-tree bridge protocol data units [BPDUs] and routing update
packets) received by the switch are subject to all ingress QoS processing.
You are likely to lose data when you change queue settings; therefore, try to make changes when
traffic is at a minimum.
Purpose
Enter global configuration mode.
Enable QoS globally.
QoS runs with the default settings described in the
Configuration" section on page
Ingress Queues" section on page
on Egress Queues" section on page
Return to privileged EXEC mode.
Verify your entries.
(Optional) Save your entries in the configuration file.
Configuring the Trust State on Ports within the QoS Domain, page 33-37
Configuring the CoS Value for an Interface, page 33-39
Configuring a Trusted Boundary to Ensure Port Security, page 33-40
Enabling DSCP Transparency Mode, page 33-41
Configuring the DSCP Trust State on a Port Bordering Another QoS Domain, page 33-42
shows a sample network topology.
33-33, the "Queueing and Scheduling on
33-14, and the
33-16.
33-44:
Catalyst 2975 Switch Software Configuration Guide
Configuring Standard QoS
"Default Standard QoS
"Queueing and Scheduling
33-37