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Software Configuration Guide—Release 12.2(25)SG
OL-7659-03
Chapter27 Configuring Quality of Service
Configuring QoS
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:
When configuring the trust state of an interface, note the following:
•You can use the no qos trust command to set the interface state to untrusted.
•For traffic received on an ingress interface configured to trust CoS using the qos trust cos command,
the transmit CoS is always the incoming packet CoS (or the ingress interface default CoS if the
packet is received untagged).
•When the interface trust state is not configured to trust dscp using the qos trust dscp command, the
security and QoS ACL classification will always use the interface DSCP and not the incoming
packet DSCP.
This example shows how to configure Gigabit Ethernet interface 1/1 wi th the trust cos keywords:
Switch# configure terminal
Enter configuration commands, one per line. End with CNTL/Z.
Switch(config)# interface gigabitethernet 1/1
Switch(config-if)# qos trust cos
Switch(config-if)# end
Switch#
This example shows how to verify the configuration:
Switch# show qos interface gigabitethernet 1/1 | include trust
Trust state: trust COS
Switch#
Command Purpose
Step1 Switch(config)# interface {vlan
vlan_ID
|
{fastethernet | gigabitethernet}
slot/interface
|
Port-channel
number
}
Selects the interface to configure.
Step2 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.
Step3 Switch(config-if)# end Exits configuration mode.
Step4 Switch# show qos Verifies the configuration.