Cisco Systems 4500 - page 841

37-91
Software Configuration Guide—Release 15.0(2)SG
OL-23818-01
Chapter 37 Configuring Quality of Service Configuring Auto-QoS on Supervisor Engine 6-E, Supervisor Engine 6L-E, Catalyst 4900M, and Catalyst 4948E
set qos-group 24
policy-map AutoQos-VoIP-Output-Policy
class AutoQos-VoIP-Bearer-QosGroup
set dscp ef
set cos 5
priority
police cir percent 33
class AutoQos-VoIP-Control-QosGroup26
set dscp af31
set cos 3
bandwidth remaining percent 5
class AutoQos-VoIP-Control-QosGroup24
set dscp cs3
set cos 3
bandwidth remaining percent 5
class class-default
dbl
The three policy maps are defined as follows:
• policy-map AutoQos-VoIP-Input-Dscp-Policy
This policy map is applied as an input service policy on an Layer 3 interface (such as an uplink
connection to a neighboring switch) when auto-QoS is configured on the port.
• policy-map AutoQos-VoIP-Input-Cos-Policy
This policy map is applied as an input service policy on an Layer 2 interface that could be either an
uplink connection or a port hooked to a Cisco IP phone.
• policy-map AutoQos-VoIP-Output-Policy
This policy map is applied as an output policy for any port on which auto-QoS is configured,
establishing policy governing egress traffic on the port based on whether it is voice data or control
traffic.
The purpose of the input policy maps is to identify voice data or control traffic and mark it as such as it
traverses the switch. The output policy map matches the packets on the marking occurring on ingress
and then applies egress parameters such as bandwidth, policing and/or priority queuing.
The invocation of auto-QoS on a switch using Catalyst 4900M, Catalyst 4948E, Supervisor Engine 6-E,
and Supervisor Engine 6L-E use the same configuration commands used on Supervisor Engines II-Plus
to V-10GE.
For switch-to-switch connections, the [no] auto qos voip trust command is used to apply an input and
output service policy on the interface:
service-policy input AutoQos-VoIP-Input-Cos-Policy
service-policy input AutoQos-VoIP-Input-Dscp-Policy
service-policy output AutoQos-VoIP-Output-Policy
The selection of the input policy depends on whether the port is Layer 2 or Layer 3. For Layer 2, the
policy trusts the CoS setting in the received packets. For Layer 3 ports, it relies on the DSCP value
contained in the packets.
For phone-connected ports, the [no] auto qos voice cisco-phone command is used to apply the following
service policy to the port:
qos trust device cisco-phone
service-policy input AutoQos-VoIP-Input-Cos-Policy
service-policy output AutoQos-VoIP-Output-Policy