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Cisco IOS VPN Configuration Guide
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Chapter 3 Site-to-Site and Extranet VPN Business Scenarios
Step 4—Configuring Quality of Service
Cisco IOS QoS service models, features, and sample configurations are explained in detail in the 
Quality 
of Service Solutions Configuration Guide
and the 
Quality of Service Solutions Command Reference
. 
Refer to these two publications as you plan and implement a QoS strategy for your VPN, because there 
are various QoS service models and features that you can implement on your VPN. See 
for information on how to access these publications.
This section contains basic steps to configure QoS weighted fair queuing (WFQ), which applies priority 
(or weights) to identified traffic on the GRE tunnel you configured in the 
. This section also contains basic steps to configure Network-Based 
Application Recognition (NBAR), which is a classification engine that recognizes a wide variety of 
applications, including web-based and other protocols that utilize dynamic TCP/UDP port assignments. 
This section includes the following topics:
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Configuring Network-Based Application Recognition
Network-Based Application Recognition (NBAR) adds intelligent network classification to network 
infrastructures. NBAR is a classification engine that recognizes a wide variety of applications, including 
web-based and other protocols that utilize dynamic TCP/UDP port assignments. When an application is 
recognized and classified by NBAR, a network can invoke services for that specific application. NBAR 
ensures that network bandwidth is used efficiently by working with QoS features.
Your interface to NBAR is through the modular QoS command-line interface (MQC). MQC provides a 
model for QoS configuration under IOS. MQC provides a clean separation between the specification of 
a classification policy and the specification of other policies that act based on the results of the applied 
classification.
Configuring a QoS policy typically requires the configuration of traffic classes, the configuration of 
policies that will be applied to those traffic classes, and the attaching of policies to interfaces using the 
commands in the sections that follow.
The following tasks are required to configure NBAR: