CCNP Voice FAQ: Implementing AutoQoS

Answer: B

Answer: B

Answer: A

Answer: D

Answer: D

Answer: A

Answer: C

Answer: C

Answer: D

Answer: B

Answer: Cisco AutoQoS has many benefits, including the following:

• It uses Cisco IOS built-in intelligence to automate generation of QoS configurations for most common business scenarios.
• It protects business-critical data applications in the Enterprise to maximize their availability.
• It simplifies QoS deployment.
• It reduces configuration errors.
• It makes QoS deployment cheaper, faster, and simpler.
• It follows the DiffServ model.
• It allows customers to have complete control over their QoS configuration.
• It enables customers to modify and tune the configurations that Cisco AutoQoS automatically
• generates to meet their specific needs or changes to the network conditions.

Answer: The two phases of AutoQoS evolution are AutoQoS VoIP and AutoQoS for Enterprise.

Answer: Cisco AutoQoS addresses the following five key elements:

• Application classification
• Policy generation
• Configuration
• Monitoring and reporting
• Consistency

Answer: NBAR protocol discovery is able to identify and classify the following:

• Applications that target a session to a well-known (UDP/TCP) destination port number, referred to as static port applications
• Applications that start a control session using a well-known port number but negotiate another port number for the session, referred to as dynamic port applications
• Some non-IP applications
• HTTP applications based on URL, MIME type, or host name

Answer: You can enable Cisco AutoQoS on the following types of router interfaces or PVCs:

• Serial interfaces with PPP or HDLC encapsulation.
• Frame Relay point-to-point subinterfaces. (Multipoint is not supported.)
• ATM point-to-point subinterfaces (PVCs) on both slow (<=768 kbps) and fast serial (>768 kbps) interfaces.
• Frame Relay-to-ATM interworking links

Answer: The router prerequisites for configuring AutoQoS are as follows:

• The router cannot have a QoS policy attached to the interface.
• You must enable CEF on the router interface (or PVC).
• You must specify the correct bandwidth on the interface or subinterface.
• You must configure a low-speed interface (<= 768 Kbps) and an IP address.

Answer: Following are the two steps (or phases) of AutoQoS for Enterprise:

1. Traffic is profiled using autodiscovery. You do this by entering the auto qos discovery command in the interface configuration mode.
2. MQC-based QoS policies are generated and deployed. You do this by entering the auto qos command in interface configuration mode.

Answer: Following are the commands for verifying AutoQoS on Cisco routers:

• show auto discovery qos allows you to examine autodiscovery results.
• show auto qos allows you to examine Cisco AutoQoS templates and initial configuration.
• show policy-map interface allows you to explore interface statistics for autogenerated policy.

Answer: The commands for verifying AutoQoS on Cisco LAN switches are as follows:

• show auto qos allows you to examine Cisco AutoQoS templates and the initial configuration.
• show policy-map interface allows you to explore interface statistics for autogenerated policy.
• show mls qos maps allows you to examine CoS-to-DSCP maps.

Answer: The three most common Cisco AutoQoS issues that can arise, and their corresponding solutions, are as follows:

• Too many traffic classes are generated; classification is overengineered.
  Solution: Manually consolidate similar classes to produce the number of classes needed.
• The configuration that AutoQoS generates does not automatically adapt to changing network traffic conditions.
  Solution: Run Cisco AutoQoS discovery on a periodic basis, followed by re-enabling of Cisco AutoQoS.
• The configuration that AutoQoS generates fits common network scenarios but does not fit some circumstances, even after extensive autodiscovery.
  Solution: Manually fine-tune the AutoQoS-generated configuration.

Answer: You can obtain the following information from the output of the show auto qos command:

• Number of traffic classes identified (class maps)
• Traffic classification options selected (within class maps)
• Traffic marking options selected (within policy maps)
• Queuing mechanisms deployed, and their corresponding parameters (within policy maps)
• Other QoS mechanisms deployed (within policy maps)
• Where the autogenerated policies are applied: on the interface, subinterface, or PVC

Answer: Following are the two major reasons for modifying the configuration that AutoQoS generates:

• The AutoQoS-generated commands do not completely satisfy the specific requirements of the Enterprise network.
• The network condition, policies, traffic volume and patterns, and so on might change over time, rendering the AutoQoS-generated configuration dissatisfying.

Answer: You can modify and tune the AutoQoS-generated class maps and policy maps by doing the following:

• Using Cisco QoS Policy Manager (QPM).
• Directly entering the commands one at a time at the router command-line interface using MQC.
• Copying the existing configuration, a class map for example, into a text editor and modifying the configuration using the text editor, offline. Next, using CLI, remove the old undesirable configuration and then add the new configuration by copying and pasting the text from the text editor. This is probably the easiest way.

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