Auto QoS has two versions AutoQoS VOIP for switches and routers which was developed first to deploy QoS without the need for QoS experience. The second is AutoQoS Enterprise, is for routers only and requires a two step deployment process.
There are five key elements of QoS design and deployment.
- Application Classification
- Policy Generation
Oriented to make VOIP traffic work well (duh).
Follows Cisco best practices for QoS tools for VOIP.
Requires CEF be enabled first.
Cannot be used on an interface with a previous service policy command configured.
Bandwidth command should be configured with the correct bandwidth, AutoQoS VOIP relies upon this setting.
Supports only point-to-point subinterfaces on Frame Relay interfaces.
Commands to implement AutoQoS VOIP:
(config-if)#auto qos voip
Command to remove AutoQoS VOIP:
(config)# no auto qos voip
Unless you have made local changes, then you will have to remove it manually.
Confirmation commands for AutoQoS VOIP:
(config)# show auto qos
Shows configuration generated by autoqos voip, will not show changes made to the QoS configuration.
(config)# show auto qos int s1/0
Shows the policy map on the interface
(config)# show run
Shows config as it is, with local changes to the policy.
When connecting to a trusted switch or router, use the command:
(config-if)# auto qos voip trust
This router implicitly trusts the DSCP marking sent on this interface.
When the possibility exists to connect to a phone:
(config-if)# auto qos voip cisco-phone
The switch will then use CDPv2 to check if it is a Cisco phone on the other end the trust boundary is extended.
Designed to expand the use of QoS from voice to include video, and data without an in-depth knowledge of QoS, PPP, frame relay, ATM and LFI. AutoQoS Enterprise uses a two step deployment process, the first being auto-discovery or data collection, the second step is AutoQoS template generation and installation.
AutoQoS Enterprise addresses five key elements of QoS design and deployment.
- Application Classification — Uses NBAR and CDPv2 to classify traffic.
- Policy Generation — AutoQoS Enterprise generates
- Configuration — Easily configured.
Started with the command:
(config-if)# auto discovery qos [trust]
In trust mode auto-discovery trusts the DSCP values in the IP header and uses it to classify packets, collect bandwidth statistics, calculate traffic average and traffic peak rate, then passes the data to the template module.
In untrust mode auto-discovery uses NBAR to detect application on the network to collect data and perform statistical analysis.
To show the data that has been collected:
# show auto discovery qos [interface [interface type]]
AutoQoS template generation and installation
The second stage uses the discovery results to generate class and policy map templates.
The class-map templates generated are used to classify applications and map them to classes for DiffServ PHB. AutoQoS Enterprise can define as many as 10 classes, which are designed to accommodate various enterprise applications.
Below is the table of classes and their PHB from the Cisco document “AutoQoS for the Enterprise.”
|AutoQoS Class Name
||Network control traffic, such as routing protocols
||Inactive voice-bearer traffic
||Interactive video data traffic
||Streaming media traffic
||Telephony signaling and control traffic
|Transactional/Interactive||Database applications transactional in nature
Network management traffic
||Bulk data transfers; web traffic; general data service
||Casual entertainment, rogue traffic
Default class, all non-critical traffic
The policy-map templates define interface queuing and minimum bandwidth. The templates created depend on the type of interface and bandwidth configured on the interface, which is why it is so important to define bandwidth correctly. Networkers can tune the policy-map if needed.
To show the auto qos class and policy maps:
# show auto qos [interface [interface type]]
# show policy-map interface [interface type]
AutoQoS may not work well for corner cases.
Creates too many traffic classes.
Does not adapt to changes in the network.
show auto qos
Class map match and set commands show how the traffic is marked.
Policy map priority and bandwidth show queue type and bandwidth guarantee.
Some common statements:
! Where does the traffic originate.
match input interface int
! Layer 2 CoS values.
match cos cos-value
! Layer 3 IP precedence
match ip precedence ip-prec-value
! Layer 3 IP DSCP
match ip dscp ip-dscp-value
! RTP port value
match ip rtp port-number port-range
References used besides ONT and the QoS Exam Certification Guide: