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30-10
Catalyst 2950 and Catalyst 2955 Switch Software Configuration Guide
78-11380-10
Chapter 30 Configuring QoS
Configuring Auto-QoS
You use auto-QoS commands to identify ports connected to Cisco IP Phones and to devices running the
Cisco SoftPhone application. You also use the commands to identify ports that receive trusted traffic
through an uplink. Auto-QoS then performs these functions:
• Detects the presence or absence of IP phones
• Configures QoS classification
• Configures egress queues
These sections describe how to configure auto-QoS on your switch:
• Generated Auto-QoS Configuration, page 30-10
• Effects of Auto-QoS on the Configuration, page 30-13
• Configuration Guidelines, page 30-13
• Upgrading from a Previous Software Release, page 30-14
• Enabling Auto-QoS for VoIP, page 30-14
Generated Auto-QoS Configuration
When auto-QoS is enabled, it uses the ingress packet label to classify traffic and to configure the egress
queues as described in Table 30-2.
Table 30-3 lists the generated auto-QoS configuration for the egress queues.
Table 30-2 Traffic Types, Packet Labels, and Egress Queues
VoIP
1
Data
Traffic
1. VoIP = voice over IP
VoIP Control
Traffic
Routing Protocol
Traffic
STP BPDU
2
Traffic
2. BPDU = bridge protocol data unit
Real-Time
Video Traffic All Other Traffic
DSCP 46 24, 26 48 56 34 –
CoS 5 3 6 7 4
CoS-to-Queue
Map
5 3, 6, 7 4 2 0, 1
Egress Queue Expedite
(queue 4)
70% WRR (queue 3) 20% WRR
(queue 2)
20% WRR
(queue 2)
10% WRR
(queue 1)
Table 30-3 Auto-QoS Configuration for the Egress Queues
Egress Queue Queue Number CoS-to-Queue Map Queue Weight
Expedite 4 5 –
70% WRR 3 3, 6, 7 70 percent
20% WRR 2 2, 4 20 percent
10% WRR 1 0,1 10 percent