- Preface
- Overview
- Using the Command-Line Interface
- Configuring the Switch Alarms
- Performing Switch Setup Configuration
- Configuring Cisco IOS Configuration Engine
- Configuring Switch Clusters
- Performing Switch Administration
- Configuring PTP
- Configuring PROFINET
- Configuring CIP
- Configuring SDM Templates
- Configuring Switch-Based Authentication
- Configuring IEEE 802.1x Port-Based Authentication
- Configuring Web-Based Authentication
- Configuring Interface Characteristics
- Configuring Smartports Macros
- Configuring VLANs
- Configuring VTP
- Configuring Voice VLAN
- Configuring STP
- Configuring MSTP
- Configuring Optional Spanning-Tree Features
- Configuring Resilient Ethernet Protocol
- Configuring Flex Links and the MAC Address-Table Move Update Feature
- Configuring DHCP
- Configuring Dynamic ARP Inspection
- Configuring IP Source Guard
- Configuring IGMP Snooping and MVR
- Configuring Port-Based Traffic Control
- Configuring SPAN and RSPAN
- Configuring LLDP, LLDP-MED, and Wired Location Service
- Configuring CDP
- Configuring UDLD
- Configuring RMON
- Configuring System Message Logging
- Configuring SNMP
- Configuring Network Security with ACLs
- Configuring QoS
- Configuring Auto-QoS
- Configuring EtherChannels
- Configuring Static IP Unicast Routing
- Configuring IPv6 Host Functions
- Configuring Link State Tracking
- Configuring IPv6 MLD Snooping
- Configuring Cisco IOS IP SLAs Operations
- Configuring Layer 2 Network Address Translation
- Troubleshooting the Cisco IOS Software
- Working with the Cisco IOS File System, Configuration Files, and Software Images
Configuring Auto-QoS
Finding Feature Information
Your software release may not support all the features documented in this chapter. For the latest feature information and caveats, see the release notes for your platform and software release.
Use Cisco Feature Navigator to find information about platform support and Cisco software image support. To access Cisco Feature Navigator, go to http://www.cisco.com/go/cfn. An account on Cisco.com is not required.
Prerequisites for Auto-QoS
Restrictions for Auto-QoS
- To use this feature, the switch must be running the LAN Base image.
- Connected devices must use Cisco Call Manager Version 4 or later.
- This release supports only Cisco IP SoftPhone Version 1.3(3) or later.
- To take advantage of the auto-QoS defaults, you should enable auto-QoS before you configure other QoS commands. If necessary, you can fine-tune the QoS configuration, but we recommend that you do so only after the auto-QoS configuration is completed. For more information, see the Effects of Auto-QoS on the Configuration.
- 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.
- Auto-QoS configures the switch for VoIP with Cisco IP phones on nonrouted and routed ports. Auto-QoS also configures the switch for VoIP with devices running the Cisco SoftPhone application.
- When a device running Cisco SoftPhone is connected to a nonrouted or routed port, the switch supports only one Cisco SoftPhone application per port.
- Auto-Qos VoIP uses the priority-queue interface configuration command for an egress interface. You can also configure a policy-map and trust device on the same interface for Cisco IP phones.
- After auto-QoS is enabled, do not modify a policy map or aggregate policer that includes AutoQoS in its name. If you need to modify the policy map or aggregate policer, make a copy of it, and change the copied policy map or policer. To use this new policy map instead of the generated one, remove the generated policy map from the interface, and apply the new policy map to the interface.
- You can enable auto-QoS on static, dynamic-access, voice VLAN access, and trunk ports.
Information About Auto-QoS
This chapter describes how to configure quality of service (QoS) by using automatic QoS (auto-QoS) command on the switch. With QoS, you can provide preferential treatment to certain types of traffic at the expense of others. Without QoS, the switch offers best-effort service to each packet, regardless of the packet contents or size. It sends the packets without any assurance of reliability, delay bounds, or throughput.
You can configure QoS on physical ports and on switch virtual interfaces (SVIs). Other than to apply policy maps, you configure the QoS settings, such as classification, queueing, and scheduling, the same way on physical ports and SVIs. When configuring QoS on a physical port, you apply a nonhierarchical policy map to a port. When configuring QoS on an SVI, you apply a nonhierarchical policy map.
The switch supports some of the modular QoS CLI (MQC) commands. For more information about the MQC commands, see the “Modular Quality of Service Command-Line Interface Overview” chapter of the Cisco IOS Quality of Service Solutions Guide.
Auto-QoS
You can use the auto-QoS feature to simplify the deployment of QoS features. Auto-QoS determines the network design and enables QoS configurations so that the switch can prioritize different traffic flows. It uses the ingress and egress queues instead of using the default (disabled) 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 classification results to choose the appropriate egress queue.
Auto-QoS supports IPv4 and IPv6 traffic when you configure the dual IPv4 and IPv6 SDM template with the sdm prefer dual ipv4-and-ipv6 global configuration command.
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:
Generated Auto-QoS Configuration
By default, auto-QoS is disabled on all ports.
When auto-QoS is enabled, it uses the ingress packet label to categorize traffic, to assign packet labels, and to configure the ingress and egress queues as shown in Table 39-1 .
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Table 39-2 shows the generated auto-QoS configuration for the ingress queues.
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Table 39-3 shows the generated auto-QoS configuration for the egress queues.
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When you enable the auto-QoS feature on the first port, these automatic actions occur:
- QoS is globally enabled (mls qos global configuration command), and other global configuration commands are added.
- When you enter the auto qos voip cisco-phone interface configuration command on a port at the edge of the network that is connected to a Cisco IP phone, the switch enables the trusted boundary feature. The switch uses the Cisco Discovery Protocol (CDP) to detect the presence or absence of a Cisco IP phone. When a Cisco IP phone is detected, the ingress classification on the port is set to trust the QoS label received in the packet. The switch also uses policing to determine whether a packet is in or out of profile and to specify the action on the packet. If the packet does not have a DSCP value of 24, 26, or 46 or is out of profile, the switch changes the DSCP value to 0. When a Cisco IP phone is absent, the ingress classification is set to not trust the QoS label in the packet. The switch configures ingress and egress queues on the port according to the settings in Table 39-2 and Table 39-3 . The policing is applied to those traffic matching the policy-map classification before the switch enables the trust boundary feature.
- When you enter the auto qos voip cisco-softphone interface configuration command on a port at the edge of the network that is connected to a device running the Cisco SoftPhone, the switch uses policing to determine whether a packet is in or out of profile and to specify the action on the packet. If the packet does not have a DSCP value of 24, 26, or 46 or is out of profile, the switch changes the DSCP value to 0. The switch configures ingress and egress queues on the port according to the settings in Table 39-2 and Table 39-3 .
- When you enter the auto qos voip trust interface configuration command on a port connected to the interior of the network, the switch trusts the CoS value for nonrouted ports or the DSCP value for routed ports in ingress packets (the assumption is that traffic has already been classified by other edge devices). The switch configures the ingress and egress queues on the port according to the settings in Table 39-2 and Table 39-3 .
For information about the trusted boundary feature, see the “Configuring a Trusted Boundary to Ensure Port Security” section.
When you enable auto-QoS by using the auto qos voip cisco-phone, the auto qos voip cisco-softphone, or the auto qos voip trust interface configuration command, the switch automatically generates a QoS configuration based on the traffic type and ingress packet label and applies the commands listed in Table 39-4 to the port.
Effects of Auto-QoS on the Configuration
When auto-QoS is enabled, the auto qos voip interface configuration command and the generated configuration are added to the running configuration.
The switch applies the auto-QoS-generated commands as if the commands were entered from the CLI. An existing user configuration can cause the application of the generated commands to fail or to be overridden by the generated commands. These actions occur without warning. If all the generated commands are successfully applied, any user-entered configuration that was not overridden remains in the running configuration. Any user-entered configuration that was overridden can be retrieved by reloading the switch without saving the current configuration to memory. If the generated commands fail to be applied, the previous running configuration is restored.
To display the QoS commands that are automatically generated when auto-QoS is enabled or disabled, enter the debug auto qos privileged EXEC command before enabling auto-QoS. For more information, see the debug autoqos command in the command reference for this release.
To disable auto-QoS on a port, use the no auto qos voip interface configuration command. Only the auto-QoS-generated interface configuration commands for this port are removed. If this is the last port on which auto-QoS is enabled and you enter the no auto qos voip command, auto-QoS is considered disabled even though the auto-QoS-generated global configuration commands remain (to avoid disrupting traffic on other ports affected by the global configuration).
You can use the no mls qos global configuration command to disable the auto-QoS-generated global configuration commands. With QoS disabled, there is no concept of trusted or untrusted ports because the packets are not modified (the CoS, DSCP, and IP precedence values in the packet are not changed). Traffic is switched in pass-through mode (packets are switched without any rewrites and classified as best effort without any policing).
How to Configure Auto-QoS
Enabling Auto-QoS for VoIP
Configuring QoS to Prioritize VoIP Traffic
This task explains how to configure the switch at the edge of the QoS domain to prioritize the VoIP traffic over all other traffic:
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Enables debugging for auto-QoS. When debugging is enabled, the switch displays the QoS configuration that is automatically generated when auto-QoS is enabled. |
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Specifies the switch port connected to the Cisco IP phone, and enters interface configuration mode. |
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Enables auto-QoS on the port, and specifies that the port is connected to a Cisco IP phone. The QoS labels of incoming packets are trusted only when the Cisco IP phone is detected. |
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Repeat Steps 4 to 6 for as many ports as are connected to the Cisco IP phone. |
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Specifies the switch port identified as connected to a trusted switch or router, and enters interface configuration mode. See Figure 39-1. |
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Enables auto-QoS on the port, and specifies that the port is connected to a trusted router or switch. |
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Monitoring and Maintaining Auto-QoS
Configuration Examples for Auto-QoS
Auto-QoS Network: Example
This is an illustrated example that shows you how to implement auto-QoS in a network in which the VoIP traffic is prioritized over all other traffic. Auto-QoS is enabled on the switches in the wiring closets at the edge of the QoS domain.
For optimum QoS performance, enable auto-QoS on all the devices in the network.
Figure 39-1 Auto-QoS Configuration Example Network
Enabling Auto-QoS VOIP Trust: Example
This example shows how to enable auto-QoS and to trust the QoS labels received in incoming packets when the switch or router connected to a port is a trusted device:
Additional References
The following sections provide references related to switch administration:
Related Documents
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Standards
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No new or modified standards are supported by this feature, and support for existing standards has not been modified by this feature. |
MIBs
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To locate and download MIBs using Cisco IOS XR software, use the Cisco MIB Locator found at the following URL and choose a platform under the Cisco Access Products menu: http://cisco.com/public/sw-center/netmgmt/cmtk/mibs.shtml |
RFCs
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No new or modified RFCs are supported by this feature, and support for existing RFCs has not been modified by this feature. |