Cisco 3750G Configuration Guide - Page 747

Chapter 33 Configuring QoS Configuring Standard QoS General QoS Guidelines These are general QoS guidelines: • Control traffic (such as spanning-tree bridge protocol data units [BPDUs] and routing update packets) received by the switch are subject to all ingress QoS processing. • You are likely to lose data when you change queue settings; therefore, try to make changes when traffic is at a minimum. Beginning with Cisco IOS Release 12.2(35)SE, a switch that is running the IP services image supports QoS DSCP and IP precedence matching in policy-based routing (PBR) route maps with these limitations: • You cannot apply QoS DSCP mutation maps and PBR route maps to the same interface. • You cannot configure DSCP transparency and PBR DSCP route maps on the same switch. Enabling QoS Globally By default, QoS is disabled on the switch. Beginning in privileged EXEC mode, follow these steps to enable QoS. This procedure is required. Step 1 Step 2 Step 3 Step 4 Step 5 Command configure terminal mls qos end show mls qos copy running-config startup-config Purpose Enter global configuration mode. Enable QoS globally. QoS runs with the default settings described in the "Default Standard QoS Configuration" section on page 33-31, the "Queueing and Scheduling on Ingress Queues" section on page 33-15, and the "Queueing and Scheduling on Egress Queues" section on page 33-17. Return to privileged EXEC mode. Verify your entries. (Optional) Save your entries in the configuration file. To disable QoS, use the no mls qos global configuration command. Enabling VLAN-Based QoS on Physical Ports By default, VLAN-based QoS is disabled on all physical switch ports. The switch applies QoS, including class maps and policy maps, only on a physical-port basis. In Cisco IOS Release 12.2(25)SE or later, yYou can enable VLAN-based QoS on a switch port. OL-8550-02 Catalyst 3750 Switch Software Configuration Guide 33-35