Contents
- AutoQoS—VoIP
- Finding Feature Information
- Prerequisites for AutoQoS—VoIP
- Restrictions for AutoQoS—VoIP
- Information About AutoQoS—VoIP
- Benefits of AutoQoS—VoIP
- Design Considerations
- Configurations for the Interface Configurations Policy Maps Class Maps and ACLs
- How to Configure the AutoQoS—VoIP Feature
- Enabling the AutoQoS—VoIP Feature
- FAQs and Troubleshooting Tips
- What to Do Next
- Verifying the Configuration
- Configuration Examples for AutoQoS—VoIP
- Examples: Configuring the AutoQoS—VoIP Feature
- Examples: Verifying the AutoQoS—VoIP Feature Configuration
- Additional References for AutoQoS—VoIP
- Feature Information for AutoQoS—VoIP
AutoQoS—VoIP
The AutoQoS—VoIP feature allows you to automate the delivery of quality of service (QoS) on your network and provides a means for simplifying the implementation and provisioning of QoS for Voice over IP (VoIP) traffic.
- Finding Feature Information
- Prerequisites for AutoQoS—VoIP
- Restrictions for AutoQoS—VoIP
- Information About AutoQoS—VoIP
- How to Configure the AutoQoS—VoIP Feature
- Configuration Examples for AutoQoS—VoIP
- Additional References for AutoQoS—VoIP
- Feature Information for AutoQoS—VoIP
Finding Feature Information
Your software release may not support all the features documented in this module. For the latest caveats and feature information, see Bug Search Tool and the release notes for your platform and software release. To find information about the features documented in this module, and to see a list of the releases in which each feature is supported, see the feature information table at the end of this module.
Use Cisco Feature Navigator to find information about platform support and Cisco software image support. To access Cisco Feature Navigator, go to www.cisco.com/go/cfn. An account on Cisco.com is not required.
Prerequisites for AutoQoS—VoIP
Restrictions for AutoQoS—VoIP
General Restrictions
The AutoQoS—VoIP feature is supported on the following interfaces, data-link connection identifiers (DLCIs), and permanent virtual circuits (PVCs) only:
The AutoQoS—VoIP feature is supported on low-speed ATM PVCs in point-to-point subinterfaces only. The AutoQoS—VoIP feature is supported on high-speed ATM PVCs in any type of subinterface.
Note | An ATM PVC is classified as low-speed if its bandwidth is less than or equal to 768 kb/s; an ATM PVC is classified as high-speed if its bandwidth is greater than 768 kb/s |
Serial Interface Restrictions
For a serial interface with a low-speed link, Multilink PPP (MLP) is configured automatically. The serial interface must have an IP address. When MLP is configured, this IP address is removed and put on the MLP bundle. To ensure that the traffic goes through the low-speed link, the following conditions must be met:
Frame Relay DLCI Restrictions
- The AutoQoS—VoIP feature cannot be configured on a Frame Relay DLCI if a map class is attached to the DLCI.
- If a Frame Relay DLCI is already assigned to one subinterface, the AutoQoS—VoIP feature cannot be configured from a different subinterface.
- For low-speed Frame Relay DLCIs configured for use on Frame Relay-to-ATM networks, MLP over Frame Relay (MLPoFR) is configured automatically. The subinterface must have an IP address.
When MLPoFR is configured, this IP address is removed and put on the MLP bundle. The AutoQoS—VoIP feature must also be configured on the ATM side of the network.
ATM PVC Restrictions
- For a low-speed ATM PVC, the AutoQoS—VoIP feature cannot be configured if a virtual template is already configured for the ATM PVC.
- For low-speed ATM PVCs, MLP over ATM (MLPoATM) is configured automatically. The subinterface must have an IP address.
When MLPoATM is configured, this IP address is removed and put on the MLP bundle. The AutoQoS—VoIP feature must also be configured on the ATM side of the network.
Information About AutoQoS—VoIP
- Benefits of AutoQoS—VoIP
- Design Considerations
- Configurations for the Interface Configurations Policy Maps Class Maps and ACLs
Benefits of AutoQoS—VoIP
The key benefits of the AutoQoS—VoIP feature include the following:
You can implement the QoS features required for VoIP traffic without an in-depth knowledge of the following underlying technologies: - The AutoQoS—VoIP feature simplifies QoS implementation and speeds up the provisioning of QoS technology over a Cisco network. It reduces human error and lowers training costs. With the AutoQoS—VoIP feature, one command (the auto qos command) enables QoS for VoIP traffic across every Cisco device.
- You can also use existing Cisco commands to modify the configurations automatically generated by the AutoQoS—VoIP feature as needed to meet specific requirements.
Design Considerations
General QoS Requirements
- Recommended methods and values are configured to meet the QoS requirements for voice traffic.
The AutoQoS—VoIP feature takes the interface type and bandwidth into consideration when implementing the following QoS features: - Classification, used to differentiate the voice packets from the data packets and handle the voice packets appropriately.
- Low latency queueing (LLQ)/Priority Queueing (PQ). This feature (specifically, PQ) is applied to the voice packets to meet the latency requirements.
- Compressed Real-Time Protocol (cRTP). With cRTP, the 40-byte IP header of the voice packet is reduced from 2 to 4 bytes, thereby reducing voice bandwidth requirements. cRTP must be applied at both ends of a network link.
- LFI, used to reduce the jitter of voice packets by preventing voice packets from getting delayed behind large data packets in a queue. LFI must be applied at both ends of a network link.
Bandwidth Implications
- The bandwidth of the serial interface determines the speed of the link. The speed of the link in turn determines the configurations generated by the AutoQoS—VoIP feature.
Note | Changing the bandwidth after configuring the AutoQoS—VoIP feature is not recommended. |
The AutoQoS—VoIP feature uses the bandwidth at the time the feature is configured. AutoQoS—VoIP does not respond to changes made to bandwidth after the feature is configured.
For example, if the auto qos voip command is used to configure the AutoQoS—VoIP feature on an interface with 1000 kb/s, the AutoQoS—VoIP feature generates configurations for high-speed interfaces. However, if the bandwidth is later changed to 500 kb/s, the AutoQoS—VoIP feature will not use the lower bandwidth. The AutoQoS—VoIP feature retains the higher bandwidth and continues to use the generated configurations for high-speed interfaces.
To force the AutoQoS—VoIP feature to use the lower bandwidth (and thus generate configurations for the low-speed interfaces), use the no auto qos voip command to remove the AutoQoS—VoIP feature and then reconfigure the feature.
Fragmentation for Frame Relay Networks
- For Frame Relay networks, fragmentation is configured using a delay of 10 milliseconds (ms) and a minimum fragment size of 60 bytes. This ensures that the VoIP packets are not fragmented. However, when the G.711 coder-decoder (codec) is used on low-speed links, the fragment size configured by the AutoQoS—VoIP feature could be smaller than the size of the G.711 VoIP packet.
To solve this potential problem, choose one of the following:
- Change the fragment size to the required value.
- Change the size of the G.711 VoIP packet to a smaller value.
For example, if the AutoQoS—VoIP feature is configured on a Frame Relay DLCI with 128 kb/s, the fragment size configured by the AutoQoS—VoIP feature will be 160 bytes. The size of the G.711 VoIP packet will be 160 bytes, minus the bytes in the packet headers for the layers. The workaround is to either change the fragment size from 160 bytes to 220 bytes or change the size of the G.711 VoIP packet from 160 bytes to 80 bytes.
Signaling Protocols
The AutoQoS—VoIP feature currently identifies the following signaling protocols:
- H.323
- H.225 (Unicast only)
- Session Initiation Protocol (SIP)
- "Skinny" gateway protocol
- Media Gateway Control Protocol (MGCP)
Note | Access control lists (ACLs) can be configured to identify any additional signaling protocols that may be needed. |
Configurations for the Interface Configurations Policy Maps Class Maps and ACLs
The AutoQoS—VoIP feature automatically creates configurations that are then used for the interface configurations, policy maps, class maps, and ACLs. The interface configurations, policy maps, class maps, and ACLs are created to classify VoIP packets and to provide the appropriate QoS treatment for the network traffic.
This feature also creates interface-specific (or PVC-specific) configurations. These interface-specific (or PVC-specific) configurations are created according to the interface type and the link speed.
Note | Links with bandwidths lower than or equal to 768 kb/s are considered low-speed links; links with bandwidths higher than 768 kb/s are considered high-speed links. |
How to Configure the AutoQoS—VoIP Feature
Enabling the AutoQoS—VoIP Feature
Before using the auto qos command at an interface or an ATM PVC, ensure that the following prerequisites have been met:
- Cisco Express Forwarding (CEF) must be enabled at the interface or ATM PVC.
- If the interface or subinterface has a link speed of 768 kb/s or lower, configure the primary or secondary IP address of the interface by using the ip address command.
- For all interfaces or subinterfaces, configure the amount of bandwidth by using the bandwidth command. The amount of bandwidth allocated should be based on the link speed of the interface.
- For an ATM PVC, configure the variable bit rate (VBR) by using either the vbr-nrt command or the vbr-rt command or configure the constant bit rate (CBR) by using the cbr command.
Note |
1.
enable
2.
configure
terminal
3.
interface
type
number
4.
bandwidth
kilobits
5.
vbr-nrt
output-pcr
output-scr
output-mbs
[input-pcr] [input-scr] [input-mbs]
6.
vbr-rt
peak-rate
average-rate
burst
7.
cbr
rate
8.
pvc
[name]
vpi
/
vci [ces |
ilmi |
qsaal |
smds]
9.
ip
address
ip-address
mask
secondary
10.
frame-relay
interface-dlci
dlci
[ietf |
cisco] [voice-cir
cir] [ppp
virtual-template-name]
11.
auto qos voip
[trust] [fr-atm]
12.
exit
DETAILED STEPS
FAQs and Troubleshooting Tips
Below are answers to frequently asked questions (FAQs) and tips for troubleshooting situations that you may encounter when configuring or using the AutoQoS—VoIP feature.
Why can’t I configure the AutoQoS—VoIP feature?
- To configure the feature, CEF must be is enabled. Verify that CEF is enabled on your network.
- Also, the feature cannot be enabled if a service policy is already attached to the interface. Determine whether there is a service policy attached to the interface. If so, remove the service policy from the interface.
Why isn’t the AutoQoS—VoIP feature supported on my device?
Why are some of my QoS configurations still present after I disable the AutoQoS—VoIP feature?
Why did my low-speed network link go down when I enabled the AutoQoS—VoIP feature?
Why can’t I establish an end-to-end connection on the Frame Relay link?
What to Do Next
If the interface configurations, policy maps, class maps, and ACLs created (on the basis of the configurations created by the AutoQoS—VoIP feature) do not meet the needs of your network, the interface configurations, policy maps, class maps, and ACLs can be modified using the appropriate Cisco commands.
Note | While you can modify the interface configurations, policy maps, class maps, and ACLs, they may not be removed properly when the AutoQoS—VoIP feature is disabled using the no auto qos command. You may need to manually remove any modified interface configurations, policy maps, class maps, and ACLs. For more information about the no auto qos command, see the Cisco IOS Quality of Service Solutions Command Reference. |
Verifying the Configuration
1.
enable
2.
show
auto
qos
[interface
[interface
type]]
3.
show
policy-map
interface
[interface
type]
4.
exit
DETAILED STEPS
Command or Action | Purpose | |
---|---|---|
Step 1 |
enable
Example: Device> enable |
Enables privileged EXEC mode. |
Step 2 |
show
auto
qos
[interface
[interface
type]]
Example: Device# show auto qos interface s4/0 |
(Optional) Displays the interface configurations, policy maps, class maps, and ACLs created on the basis of automatically generated configurations. |
Step 3 |
show
policy-map
interface
[interface
type]
Example: Device# show policy-map interface s4/0 |
(Optional) Displays the packet statistics of all classes that are configured for all service policies either on the specified interface or subinterface or on a specific PVC on the interface. |
Step 4 |
exit
Example: Device# exit |
(Optional) Exits privileged EXEC mode. |
Configuration Examples for AutoQoS—VoIP
- Examples: Configuring the AutoQoS—VoIP Feature
- Examples: Verifying the AutoQoS—VoIP Feature Configuration
Examples: Configuring the AutoQoS—VoIP Feature
When the auto qos voip command is used to configure the AutoQoS—VoIP feature, configurations are generated. These configurations are then used to create interface configurations, policy maps, class maps, and ACLs.
This section contains examples of configuring the AutoQoS—VoIP feature on the interfaces, PVCs, and links.
Example: Configuring the AutoQoS—VoIP Feature on a High-Speed Serial Interface
In this example, the AutoQoS—VoIP feature is configured on the high-speed serial interface 1/2.
Device> enable Device# configure terminal Device(config)# interface serial 1/2 Device(config-if)# bandwidth 1540 Device(config-if)# auto qos voip Device(config-if)# exit
Example: Configuring the AutoQoS—VoIP Feature on a Low-Speed Serial Interface
In this example, the AutoQoS—VoIP feature is configured on the low-speed serial interface 1/3.
Device# configure terminal Device(config)# interface serial 1/3 Device(config-if)# bandwidth 512 Device(config-if)# ip address 10.10.100.1 255.255.255.0 Device(config-if# auto qos voip Device(config-if)# exit
Example: Configuring the AutoQoS—VoIP Feature on High-Speed Frame Relay Interfaces
In this example, the AutoQoS—VoIP feature is configured on the high-speed serial point-to-point Frame Relay subinterface 4/1.2.
Device> enable Device# configure terminal Device(config)#interface serial 4/1.2 point-to-point Device(config-if)# bandwidth 1540 Device(config-if)# frame-relay interface-dlci 100 Device(config-fr-dlci)# auto qos voip Device(config-if)# exit
Example: Configuring the AutoQoS—VoIP Feature on Low-Speed Frame Relay Interfaces
In this example, the AutoQoS—VoIP feature is configured on the low-speed point-to-point Frame Relay subinterface 4/2.1.
Device# configure terminal Device(config)# interface serial 4/2.1 point-to-point Device(config-if)# bandwidth 512 Device(config-if)# ip address 10.10.100.1 255.255.255.0 Device(config-if)# frame-relay interface-dlci 100 Device(config-fr-dlci)# auto qos voip Device(config-if)# exit
Example: Configuring the AutoQoS—VoIP Feature on a High-Speed ATM PVC
In this example, the AutoQoS—VoIP feature is configured on the high-speed point-to-point ATM PVC ATM5/0.1.
Device# configure terminal Device(config)# interface ATM5/0.1 point-to-point Device(config-if)# pvc 1/32 Device(config-if)# vbr-nrt 1540 1540 Device(config-if)# auto qos voip Device(config-if)# exit
Example: Configuring the AutoQoS—VoIP Feature on a Low-Speed ATM PVC
In this example, the AutoQoS—VoIP feature is configured on a low-speed point-to-point ATM PVC ATM5/0.2.
Device# configure terminal Device(config)# interface ATM5/0.2 point-to-point Device(config-if)# ip address 10.10.100.1 255.255.255.0 Device(config-if)# pvc 1/32 Device(config-if)# vbr-nrt 512 512 Device(config-if)# auto qos voip Device(config-if)# exit
Example: Configuring the AutoQoS—VoIP Feature for Frame Relay-to-ATM Interworking
In this example, the AutoQoS—VoIP feature is configured for Frame Relay-to-ATM Interworking. The AutoQoS—VoIP feature is configured on the serial point-to-point subinterface 1/3.1.
Device# configure terminal Device(config)# interface serial 1/3.1 point-to-point Device(config-if)# bandwidth 512 Device(config-if)# ip address 10.10.100.1 255.255.255.0 Device(config-if)# frame-relay interface-dlci 100 Device(config-if)# auto qos voip fr-atm Device(config-if)# exit
In this configuration, the optional fr-atm keyword is used to enable the AutoQoS—VoIP feature for the Frame Relay-to-ATM Interworking.
Note | The ATM-to-ATM side of the network needs no special configuration to distinguish it from the ATM-to-Frame Relay side of the network. |
Examples: Verifying the AutoQoS—VoIP Feature Configuration
When the auto qos voip command is used to configure the AutoQoS—VoIP feature, configurations are generated. These configurations are then used to create interface configurations, policy maps, class maps, and ACLs. The show auto qos interface command can be used to verify the contents of the interface configurations, policy maps, class maps, and ACLs.
This section contains the following sample output of the show auto qos interface command for interfaces, PVCs, and links.
Note | The show auto qos interface command output displays only those configurations created by the AutoQoS—VoIP feature. |
Sample show auto qos interface Command Output for a High-Speed Serial Interface
The following is sample output from the show auto qos command for a high-speed serial interface:
Device# show auto qos interface serial 6/0 Serial6/0 - ! interface Serial6/0 service-policy output AutoQoS-Policy-UnTrust
Sample show auto qos interface Command Output for a Low-Speed Serial Interface
The following is sample output from the show auto qos command for a low-speed serial interface:
Device# show auto qos interface serial 6/0 Serial6/0 - ! interface Serial6/0 no ip address encapsulation ppp no fair-queue ppp multilink multilink-group 2001100126 ! interface Multilink2001100126 bandwidth 512 ip address 10.10.100.1 255.255.255.0 service-policy output AutoQoS-Policy-UnTrust ppp multilink ppp multilink fragment-delay 10 ppp multilink interleave ip rtp header-compression iphc-format
Sample show auto qos Interface Command Output for a High-Speed Frame Relay Interface
The following is sample output from the show auto qos command for a high-speed Frame Relay interface:
Device# show auto qos interface serial6/1.1 Serial6/1.1: DLCI 100 - ! interface Serial6/1 frame-relay traffic-shaping ! interface Serial6/1.1 point-to-point frame-relay interface-dlci 100 class AutoQoS-VoIP-FR-Serial6/1-100 ! map-class frame-relay AutoQoS-VoIP-FR-Serial6/1-100 frame-relay cir 1540000 frame-relay bc 15400 frame-relay be 0 frame-relay mincir 1540000 service-policy output AutoQoS-Policy-UnTrust
Note | The output from the show auto qos interface command for high-speed Frame Relay interfaces is similar to the output for low-speed Frame Relay interfaces. The only difference is that Frame Relay Fragmentation and cRTP are not configured for high-speed Frame Relay interfaces. |
Sample show auto qos interface Command Output for a Low-Speed Frame Relay Interface
The following is sample output from the show auto qos command for a low-speed Frame Relay interface:
Device# show auto qos interface serial 6/1.1 Serial6/1.1: DLCI 100 - ! interface Serial6/1 frame-relay traffic-shaping ! interface Serial6/1.1 point-to-point frame-relay interface-dlci 100 class AutoQoS-VoIP-FR-Serial6/1-100 frame-relay ip rtp header-compression ! map-class frame-relay AutoQoS-VoIP-FR-Serial6/1-100 frame-relay cir 512000 frame-relay bc 5120 frame-relay be 0 frame-relay mincir 512000 service-policy output AutoQoS-Policy-UnTrust frame-relay fragment 640
Sample show auto qos interface Command Output for a High-Speed ATM PVC
The following is sample output from the show auto qos command for a high-speed ATM PVC:
Device# show auto qos interface atm 2/0.1 ATM2/0.1: PVC 1/100 - ! interface ATM2/0.1 point-to-point pvc 1/100 tx-ring-limit 3 service-policy output AutoQoS-Policy-UnTrust
Sample show auto qos interface Command Output for a Low-Speed ATM PVC
The following is sample output from the show auto qos command for a low-speed ATM PVC:
Device# show auto qos interface atm 2/0.1 ATM2/0.1: PVC 1/100 - ! interface ATM2/0.1 point-to-point pvc 1/100 tx-ring-limit 3 encapsulation aal5mux ppp Virtual-Template200 ! interface Virtual-Template200 bandwidth 512 ip address 10.10.100.1 255.255.255.0 service-policy output AutoQoS-Policy-UnTrust ppp multilink ppp multilink fragment-delay 10 ppp multilink interleave
Sample show auto qos interface Command Output for Frame Relay-to-ATM Interworking Links
The following is sample output from the show auto qos command for Frame Relay-to-ATM Interworking links:
Device# show auto qos interface serial6/1.1 Serial6/1.1: DLCI 100 - ! interface Serial6/1 frame-relay traffic-shaping ! interface Serial6/1.1 point-to-point frame-relay interface-dlci 100 ppp Virtual-Template200 class AutoQoS-VoIP-FR-Serial6/1-100 ! interface Virtual-Template200 bandwidth 512 ip address 10.10.100.1 255.255.0.0 service-policy output AutoQoS-Policy-UnTrust ppp multilink ppp multilink fragment-delay 10 ppp multilink interleave ! map-class frame-relay AutoQoS-VoIP-FR-Serial6/1-100 frame-relay cir 512000 frame-relay bc 5120 frame-relay be 0 frame-relay mincir 512000
Additional References for AutoQoS—VoIP
Use Cisco Feature Navigator to find information about platform support and software image support. Cisco Feature Navigator enables you to determine which software images support a specific software release, feature set, or platform. To access Cisco Feature Navigator, go to http://www.cisco.com/go/cfn. An account on Cisco.com is not required.
Related Documents
Related Topic |
Document Title |
---|---|
QoS commands: complete command syntax, command modes, command history, defaults, usage guidelines, and examples |
Cisco IOS Quality of Service Solutions Command Reference |
LFI and cRTP |
“Header Compression” module |
Packet classification |
“Classifying Network Traffic” module |
LLQ |
“Configuring Weighted Fair Queueing” module |
Service policies (policy maps) |
“Applying QoS Features Using the MQC” module |
Frame Relay and ATM commands: complete command syntax, command modes, command history, defaults, usage guidelines, and examples |
Cisco IOS Wide-Area Networking Command Reference |
Frame Relay configuration |
“Configuring Frame Relay” module |
MLPPP |
“Configuring Media-Independent PPP and Multilink PPP” module |
SNMP |
“Configuring SNMP Support” module |
Standards
Standards |
Title |
---|---|
No new or modified standards are supported by this feature, and support for existing standards has not been modified by this feature. |
— |
MIBs
MIBs |
MIBs Link |
---|---|
No new or modified MIBs are supported by this feature, and support for existing standards has not been modified by this feature. |
To obtain lists of supported MIBs by platform and Cisco IOS release, and to download MIB modules, go to the Cisco MIB website on Cisco.com at the following URL: http://www.cisco.com/public/sw-center/netmgmt/cmtk/mibs.shtml |
RFCs
RFCs |
Title |
---|---|
No new or modified RFCs are supported by this feature, and support for existing standards has not been modified by this feature. |
— |
Technical Assistance
Description |
Link |
---|---|
The Cisco Support and Documentation website provides online resources to download documentation, software, and tools. Use these resources to install and configure the software and to troubleshoot and resolve technical issues with Cisco products and technologies. Access to most tools on the Cisco Support and Documentation website requires a Cisco.com user ID and password. |
Feature Information for AutoQoS—VoIP
The following table provides release information about the feature or features described in this module. This table lists only the software release that introduced support for a given feature in a given software release train. Unless noted otherwise, subsequent releases of that software release train also support that feature.
Use Cisco Feature Navigator to find information about platform support and Cisco software image support. To access Cisco Feature Navigator, go to www.cisco.com/go/cfn. An account on Cisco.com is not required.
Note | The table below lists only the software release that introduced support for a given feature in a given software release train. Unless noted otherwise, subsequent releases of that software release train also support that feature. |
Feature Name |
Releases |
Feature Information |
---|---|---|
AutoQoS—VoIP |
12.2(15)T Cisco IOS XE 3.1.0SG Cisco IOS XE Release 3.2SE |
The AutoQoS—VoIP feature allows you to automate the delivery of quality of service (QoS) on your network and provides a means for simplifying the implementation and provisioning of QoS for Voice over IP (VoIP) traffic. The following commands are new or modified: auto qos voip, show auto qos. In Cisco IOS XE 3.1.0SG, this feature was integrated. |