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Software Configuration Guide—Release 12.2(25)EW
OL-6696-01
Chapter 29 Configuring QoS
Configuring QoS
Note If no input QoS policy is attached to a Layer 2 interface, then the input QoS policy attached to the VLAN
(on which the packet is received), if any, is used even if the port is not configured as VLAN-based. If
you do not want this default, attach a placeholder input QoS policy to the Layer 2 interface. Similarly,
if no output QoS policy is attached to a Layer 2 interface, then the output QoS policy attached to the
VLAN (on which the packet is transmitted), if any, is used even if the port is not configured as
VLAN-based. If you do not want this default, attach a placeholder output QoS policy to the layer 2
interface.
This example shows how to configure VLAN-based QoS on Fast Ethernet interface 5/42:
Switch# configure terminal
Enter configuration commands, one per line. End with CNTL/Z.
Switch(config)# interface fastethernet 5/42
Switch(config-if)# qos vlan-based
Switch(config-if)# end
This example shows how to verify the configuration:
Switch# show qos | begin QoS is vlan-based
QoS is vlan-based on the following interfaces:
Fa5/42
Switch#
Note When a layer 2 interface is configured with VLAN-based QoS, and if a packet is received on the port for
a VLAN on which there is no QoS policy, then the QoS policy attached to the port, if any is used. This
applies for both Input and Output QoS policies.
Configuring the Trust State of Interfaces
This command configures the trust state of interfaces. By default, all interfaces are untrusted.
To configure the trust state of an interface, perform this task:
Command Purpose
Step 1
Switch(config)# interface {vlan
vlan_ID
|
{fastethernet | gigabitethernet |
tengigabitethernet}
slot/interface
| Port-channel
number
}
Selects the interface to configure.
Step 2
Switch(config-if)# [no] qos trust [dscp | cos]
Configures the trust state of an interface.
Use the no keyword to clear a configured value and
return to the default.
Step 3
Switch(config-if)# end
Exits configuration mode.
Step 4
Switch# show qos
Verifies the configuration.
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