needed can vary, depending on the volume and
nature of traffic on your network. By default, Auto Discovery
runs for three days. The Cisco AutoQoS template generation and
installation phase generates templates from the data collected
during the Auto Discovery phase, and installs the templates on
the interface. Cisco AutoQoS then uses these templates as the
basis for creating the class maps and policy maps for your
network. After creating the class maps and policy maps, Cisco
AutoQoS installs them on the interface. Cisco AutoQoS VoIP
omits the Auto Discovery phase and it goes straight to template
generation and installation. Phase 1: Traffic Profiling on
Routers with Auto Discovery
Initiate the Auto Discovery
phase by using the auto discovery qos command on the
selected interface as shown in Figure . Before using the
auto discovery qos command at the interface or ATM
PVC, ensure you meet these prerequisites as shown in Figure :
- Confirm CEF is enabled.
- If the interface or
subinterface has a link speed of 768 kbps 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. Allocate bandwidth amount based on
the link speed of the interface.
- For ATM PVCs,
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.
When running Auto Discovery, observe these
restrictions: - The auto discovery qos command
is not supported on subinterfaces.
- Do not change the
bandwidth of the interface when using the auto discovery
qos command.
- You must remove all previously
attached policies from the interface.
The optional
trust keyword indicates that the DSCP markings of a
packet are trusted (that is, relied on) for classification of
voice, video, and data traffic. If you do not specify the
optional trust keyword, Cisco AutoQoS classifies voice,
video, and data traffic using NBAR, and the packets will be
marked with the appropriate DSCP value. Note these points about
the Auto Discovery phase: - If you want to stop Auto
Discovery, use the no auto discovery qos command. This
command stops data collection and removes any data collection
reports it generated.
- If you want to view the Auto
Discovery temporary results while discovery is in progress, use
the show auto discovery qos command. This command
displays the results of the data collected up to that point
during the Auto Discovery phase.
Figure is an
example of an Auto Discovery output on which the QoS policy
will be built. Phase 2: Configuring QoS Policies on
Routers
The auto qos command generates Cisco
AutoQoS for the Enterprise templates based on data collected
during the Auto Discovery phase and then installs the templates
on the interface. AutoQoS uses these templates to create class
maps and policy maps for your network and then installs them on
the interface. Figure shows the command syntax for configuring
Cisco AutoQoS. To remove Cisco AutoQoS from the interface, use
the no form of the auto qos command. You can also
use the auto qos command to enable Cisco AutoQoS VoIP,
which does not benefit from prior Auto Discovery. If you are
using any of the earlier Cisco IOS software releases in
connected routers that only support Cisco AutoQoS VoIP, use the
voip keyword to generate Cisco AutoQoS VoIP templates.
For Cisco AutoQoS VoIP, the optional trust keyword is
used to trust (that is, rely on) the DSCP markings for
classification of voice traffic. If you do not specify the
optional trust keyword, Cisco AutoQoS classifies voice
traffic using NBAR, and marks the packets with the appropriate
DSCP value. The optional fr-atm keyword enables Cisco
AutoQoS VoIP for the Frame Relay-to-ATM interworking links.
This option is available on the Frame Relay DLCIs for Frame
Relay-to-ATM interworking only. Example: Cisco AutoQoS for
the Enterprise Router Configuration
Figure shows an
example of Cisco AutoQoS for the Enterprise configuration on a
router interface. The correct configuration procedure is as
follows: Step 1 On the interface, first configure the
offered bandwidth using the bandwidth command, configure
the IP address using the ip address command, and
configure the DLCI address using the frame-relay interface
dlci command if you are configuring a Frame Relay
subinterface. Step 2 Activate the Auto Discovery phase
using the auto-discovery qos command. For the most
accurate traffic analysis, leave the Auto Discovery phase
running for as long as possible, preferably several days. In
the Auto Discovery phase, the generated policy can optionally
be reviewed using show auto discovery qos. Step
3 Apply the generated Cisco AutoQoS policy to the interface
using the auto qos command. At this point, the Cisco
AutoQoS configuration is complete, but you can tune the
autogenerated classification and policies if necessary.
Example: Configuring Cisco AutoQoS for the Enterprise on a
High-Speed Serial Interface
The example in Figure shows
Cisco AutoQoS configured on the high-speed serial 1/2
interface. As shown, leave Auto Discovery running, preferably
for several days. Example: Configuring Cisco AutoQoS for the
Enterprise on a Low-Speed Serial Interface
The example
in Figure shows Cisco AutoQoS configured on the low-speed
serial 1/3 interface.
Content 5.1
Introducing Cisco AutoQoS 5.1.8 Verifying
Cisco AutoQoS The verification of Cisco AutoQoS typically
follows the procedure shown in the table in Figure . The
principle behind the procedure is the same for routers and
switches, with the exception that there is no Auto Discovery
phase on switches and therefore there is no requirement to
verify its results. The major command used for verification on
both routers and switches is show auto qos. The
interface-specific configuration is examined afterward. Because
Cisco Catalyst switches use the CoS-to-DSCP maps for egress
packet queuing, you can use the show mls qos maps
command to verify how Cisco AutoQoS defined these maps.
Monitoring Cisco AutoQoS on Routers
Follow these
three steps to monitor Cisco AutoQoS on Cisco routers: Step
1 Display the data collected during the Auto Discovery
phase: - Use the show auto discovery qos command
to display the data collected during the Auto Discovery phase
of Cisco AutoQoS for the Enterprise. Figure shows the command
syntax and an example.
- The suggested policy output
lets you preview class maps and policy maps before you issue
the auto qos command on the interface. You can then
continue with the Auto Discovery phase to gather more data (it
is recommended that you run Cisco AutoQoS discovery for several
days), or you can copy the existing discovery results into a
text editor and modify the autogenerated classification and
policies as desired.
- The optional interface keyword
indicates that only the configurations for the specific
interface type is displayed.
Step 2 Examine
Cisco AutoQoS templates and initial configuration: -
The show auto qos command is used to display the Cisco
AutoQoS interface templates, policy maps, class maps, and ACLs.
Figure shows the show auto qos command syntax and sample
output.
- When the interface keyword is used
along with the corresponding interface type argument,
the command displays the configurations created by Cisco
AutoQoS on the specified interface. When the interface keyword
is used but an interface type is not specified, the
command displays the configurations created by the AutoQoS on
all the interfaces or PVCs on which the AutoQoS has been