Deploying AutoQoS on IOS-Based Catalyst Switches
Note
Catalyst LAN Switches with the Catalyst operating system are configured differently than IOS-based switches. The ONT exam focuses on IOS-based switches—2960(EI), 3560, and 4500 in particular, although the 6500 is sometimes referenced. Note that the 2950/2960 switches require the Enhanced Image (EI) and not the Standard Image (SI) for AutoQoS VoIP.
Note
AutoQoS VoIP support for IP softphone is only available on the 6500 series switch, and not on the 2960/3560/4500 series.
Enabling AutoQoS VoIP on Cisco switches involves two different commands:
Command 1: Enabling AutoQoS on Access Ports to Which Either a Workstation or an IP Phone Is Connected
| Switch(config-if)#auto qos voip cisco-phone | Configures the QoS on the port and enables the trusted boundary feature for a Cisco VoIP phone. |
Note
The trusted boundary feature uses CDP to detect the presence or absence of a Cisco IP phone. When AutoQoS detects a Cisco IP phone, the ingress classification on the interface is set to trust the QoS label received in the packet. When a Cisco IP phone is absent, AutoQoS sets the ingress classification to not trust the QoS label in the packet. It also reconfigures the egress queues on the interface. This command extends the trust boundary if an IP phone is detected.
Note
Cisco Discovery Protocol version 2 (CDPv2) must be enabled on the interface. CDPv2 is used to determine whether a Cisco IP phone is connected to the port.
Command 2: Enabling AutoQoS on Ports That Are Connected to Other Trusted Devices Such as Routers and Switches
| Switch(config-if)#auto qos voip trust | Configures QoS on the port and extends the QoS trust boundary to a connected device. |
Note
This interface is usually an uplink trunk connection to another switch or router. The auto qos voip trust command also reconfigures the egress queues on the interfaces where it was applied.