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29-9
Catalyst 2950 and Catalyst 2955 Switch Software Configuration Guide
OL-10101-02
Chapter 29 Configuring QoS
Configuring Auto-QoS
You can enable the egress expedite queue and assign WRR weights to the other queues by using the
wrr-queue bandwidth weight1 weight2 weight3 0 global configuration command.
Configuring Auto-QoS
Note This feature is available only if your switch is running the EI.
You can use the auto-QoS feature to simplify the deployment of existing QoS features. Auto-QoS makes
assumptions about the network design, and as a result, the switch can prioritize different traffic flows
and appropriately use the egress queues instead of using the default QoS behavior (the switch offers
best-effort service to each packet regardless of the packet contents or size and sends it from a single
queue).
When you enable auto-QoS, it automatically classifies traffic based on the traffic type and ingress packet
label. The switch uses the resulting classification to choose the appropriate egress queue.
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 29-9
• Effects of Auto-QoS on the Configuration, page 29-11
• Configuration Guidelines, page 29-12
• Upgrading from a Previous Software Release, page 29-12
• Enabling Auto-QoS for VoIP, page 29-13
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 29-2.
Ta b l e 29-2 Traffic Types, Packet Labels, and Egress Queues
VoIP
1
Data
Traffic
VoIP Control
Traffic
Routing Protocol
Traffic
STP BPDU
2
Traffic
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 1% WRR
(queue 4)
70% WRR (queue 3) 20% WRR
(queue 2)
20% WRR
(queue 2)
10% WRR
(queue 1)