Cisco Systems IE 2000

39-4

Cisco IE 2000 Switch Software Configuration Guide

OL-25866-01

Chapter 39 Configuring Auto-QoS

Information About Auto-QoS

When you enable the auto-QoS feature on the first port, these automatic actions occur:

• QoS is globally enabled (mls qos global configuration command), and other global c onfiguration

commands are added.

• When you enter the auto qos voip cisco-phone interface configuration command on a port at the

edge of the network that is connected to a Cisco IP phone, the switch en ables the trusted boundary

feature. The switch uses the Cisco Discovery Protocol (CDP) to detect the presence or absence of a

Cisco IP phone. When a Cisco IP phone is detected, the ingress cla ssification on the port is set to

trust the QoS label received in the packet. The switch also uses policing to determine whether a

packet is in or out of profile and to specify the action on t he packet. If the packet does not have a

DSCP value of 24, 26, or 46 or is out of profile, the switch changes th e DSCP value to 0. When a

Cisco IP phone is absent, the ingress classification is set to not trust the QoS label in the packet. The

switch configures ingress and egress queues on the port according to the settings in Table 39-2 and

Table 39-3. The policing is applied to those traffic matching the policy-map classification before the

switch enables the trust boundary feature.

• When you enter the auto qos voip cisco-softphone interface configuration command on a port at

the edge of the network that is connected to a device running the Cisco SoftPhone, the switch uses

policing to determine whether a packet is in or out of profile and to specify the action on the packet.

If the packet does not have a DSCP value of 24, 26, or 46 or is out of profile, the switch changes the

DSCP value to 0. The switch configures ingress and egress queues on the port according to the

settings in Table 39-2 and Table 39-3.

• When you enter the auto qos voip trust interface configuration command on a port connected to the

interior of the network, the switch trusts the CoS value for nonrouted ports or the DSCP value for

routed ports in ingress packets (the assumption is that traffic has already been classified by other

edge devices). The switch configures the ingress and egress queues on the port according to the

settings in Table 39-2 and Table 39-3.

For information about the trusted boundary feature, see the “Configuring a Trusted Boundary to

Ensure Port Security” section on page 38-34.

When you enable auto-QoS by using the auto qos voip cisco-phone, the auto qos voip cisco-softphone,

or the auto qos voip trust interface configuration command, the switch automatically generates a QoS

configuration based on the traffic type and ingress packet label and applies the commands listed in

Table 39-4 to the port.

Tab l e 39-4 Generated Auto-QoS Configuration

Description Automatically Generated Command

The switch automatically enables standard QoS and configures

the CoS-to-DSCP map (maps CoS values in incoming packets

to a DSCP value).

Switch(config)# mls qos

Switch(config)# mls qos map cos-dscp 0 8 16 26 32 46

48 56

The switch automatically maps CoS values to an ingress queue

and to a threshold ID.

Switch(config)# no mls qos srr-queue input cos-map