27-25
Software Configuration Guide—Release 12.2(25)SG
OL-7659-03
Chapter 27 Configuring Quality of Service
Configuring QoS
Configuration Guidelines
Before beginning the QoS configuration, you should be aware of this information:
• If you have EtherChannel ports configured on your switch, you must configure QoS classification
and policing on the EtherChannel. The transmit queue configuration must be configured on the
individual physical ports that comprise the EtherChannel.
• It is not possible to match IP fragments against configured IP extended ACLs to enforce QoS. IP
fragments are transmitted as best effort. IP fragments are denoted by fields in the IP header.
• It is not possible to match IP options against configured IP extended ACLs to enforce QoS. These
packets are sent to the CPU and processed by software. IP options are denoted by fields in the IP
header.
• Control traffic (such as spanning-tree BPDUs and routing update packets) received by the switch are
subject to all ingress QoS processing.
• If you want to use the set command in the policy map, you must enable IP routing (disabled by
default) and configure an IP default route to send traffic to the next-hop device that is capable of
forwarding.
Note QoS processes both unicast and multicast traffic.
Enabling QoS Globally
To enable QoS globally, perform this task:
This example shows how to enable QoS globally:
Switch# config terminal
Switch(config)# qos
Switch(config)# end
Switch#
This example shows how to verify the configuration:
Switch# show qos
QoS is enabled globally
Switch#
Command Purpose
Step 1
Switch# conf terminal
Enter configuration mode.
Step 2
Switch(config)# qos
Enables QoS on the switch.
Use the no qos command to globally disable QoS.
Step 3
Switch(config)# end
Exits configuration mode.
Step 4
Switch# show qos
Verifies the configuration.
