Published On: August 6ᵗʰ, 2019 02:03

QoS: NBAR Configuration Guide, Cisco IOS XE Release 3S

NBAR provides two levels of application recognition—coarse-grain and fine-grain. In the Cisco IOS XE Release 3.14S, by default NBAR operates in the fine-grain mode, offering NBAR's full application recognition capabilities. By minimizing deep packet inspection, coarse-grain mode offers a performance advantage and reduces memory resource demands.

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Information About NBAR Coarse-Grain Classification

Overview of NBAR Coarse-Grain Classification

NBAR provides two levels of application recognition-coarse-grain and fine-grain. By default NBAR operates in the fine-grain mode, offering NBAR's full application recognition capabilities. The default NBAR fine-grain mode is equivalent to NBAR functionality and performance prior to introduction of separate fine-grain and coarse-grain modes. This provides full backward compatibility for existing configurations.

By minimizing deep packet inspection, coarse-grain mode offers a performance advantage and reduces memory resource demands. This mode is be used in scenarios where the full power of fine-grain classification is not required. We recommend that you use fine-grained mode when per-packet reporting is required. When specific per-packet reporting is not required, use the coarse-grained mode, as it offers performance and memory advantages.

Simplified Classification

Coarse-grain mode employs a simplified mode of classification, minimizing deep packet inspection. NBAR caches classification decisions made for earlier packets, then classifies later packets from the same server similarly.

Classification by First Packet

Most flows are classified based on the first packet of the flow, even in the case of a IP Synchronization (SYN) packet, because no payload inspection is performed. Consequently, policies apply to the entire flow rather than depending on the payload.

Limitations of Coarse-Grain Mode

Coarse-grain mode has the following limitations in metric reporting detail:

Field extraction and sub-classification—Only partially supported. In coarse-grain mode, the reported results of field extraction and sub-classification are less accurate and may be sampled.

Granularity—Caching may result in some reduction in the granularity. For example, NBAR might classify some traffic as ms-office-365 instead of as the more specific ms-office-web-apps.

Evasive applications—Classification of evasive applications such as BitTorrent, eMule, and Skype, may be less effective than in fine-grain mode which is the default NBAR. Consequently, blocking or throttling may not work as well for these applications.

Comparison of Fine-grain and Coarse-grain Modes

Coarse-grain mode has the following limitations in metric reporting detail:

Fine-Grain Mode

Coarse-Grain Mode

Classification

Full-power of deep packet inspection

Simplified classification

Some classification according to similar earlier packets.

Performance

Slower

Faster

Memory Resources

Higher memory demands

Lower memory demands

Sub-classification

Full supported

Partial support

Field Extraction

Full supported

Partial support

Ideal usage

Per-packet policy

Example:

class-map that looks for specific url

When there is no requirement for specific per-packet operations.

How to Configure NBAR Coarse-Grain Classification

Configuring the NBAR Classification Modes

SUMMARY STEPS

1. enable

2. configure terminal

3. ip nbar classification granularity coarse-grain

4. exit

5. end


DETAILED STEPS
  Command or Action Purpose
Step 1 enable


Example:
Device> enable
 
Enables privileged EXEC mode.
  • Enter your password if prompted.
 
Step 2 configure terminal


Example:
Device# configure terminal
 

Enters global configuration mode.

 
Step 3 ip nbar classification granularity coarse-grain


Example:
Device(config)# ip nbar classification granularity coarse-grain 
 

Configures the coarse-grain NBAR classification mode.

 
Step 4 exit


Example:
Device(config)# exit
 

Exits the global configuration mode and enters privileged EXEC mode.

 
Step 5 end


Example:
Device(config-if)# end
 

Returns to privileged EXEC mode.

 

Configuring a Performance Monitor Context with Application Statistics

SUMMARY STEPS

1. enable

2. configure terminal

3. performance monitor context context-name coarse-grainprofile-name

4. traffic-monitor application-client-server-stats

5. exit

6. interface type slot/port/number

7. performance monitor context context-name

8. end

9. show ip nbar classification granularity


DETAILED STEPS
  Command or Action Purpose
Step 1 enable


Example:
Device> enable
 
Enables privileged EXEC mode.
  • Enter your password if prompted.
 
Step 2 configure terminal


Example:
Device# configure terminal
 

Enters global configuration mode.

 
Step 3 performance monitor context context-name coarse-grainprofile-name


Example:
Device (config)# performance monitor context xyz profile application-statistics 
 

Enters performance monitor configuration mode, and creates a context with application-statistics profile.

Note   

Configuring an Easy Performance Monitor (ezPM) policy using the Application Statistics profile implicitly invokes the coarse-grain Network Based Application Recognition (NBAR) classification mode. However, if you need to configure fine-grain NBAR classification mode, use the ip nbar classification granularity fine-grain command after configuring the performance monitor context with application statistics profile.

 
Step 4 traffic-monitor application-client-server-stats


Example:
Device(config-perf-mon)# traffic-monitor application-client-server-stats
 

Configures the traffic monitor to monitor the specified metrics.

 
Step 5 exit


Example:
Device(config-perf-mon)# exit
 

Exits performance monitor configuration mode and enters global configuration mode.

 
Step 6 interface type slot/port/number


Example:
Device(config)# interfcace 0/2/2
 

Enters interface configuration mode.

 
Step 7 performance monitor context context-name


Example:
Device (config-if)# performance monitor context xyz
 

Configures the specified performance monitor context on the interface.

 
Step 8 end


Example:
Device(config-if)# end
 

Returns to privileged EXEC mode.

 
Step 9 show ip nbar classification granularity


Example:
Device# show ip nbar classification granularity
 

Displays the currently configured NBAR classification mode.

 

Configuration Examples for NBAR Coarse-Grain Classification

Example: Configuring the NBAR Classification Mode

The following example shows how to configure the coarse-grain classification mode of NBAR:

Device> enable
Device# configure terminal
Device (config)# ip nbar classification granularity coarse-grain
Device (config)# end

Example: Configuring a Performance Monitor Context with Application Statistics Profile

The following example shows how to configure an Easy Performance Monitor (ezPM) policy using the Application Statistics profile and invoke coarse-grain NBAR classification mode:

Device> enable
Device# configure terminal
Device(config)# performance monitor context xyz profile application-statistics
Device(config-perf-mon)# traffic-monitor application-client-server-stats
Device(config-perf-mon)# exit
Device(config)# interface gigabitEthernet 0/2/2
Device(config-if)# performance monitor context xyz
Device(config-if)# end

Example: Configuring a Performance Monitor Context with Application Statistics Profile and Force-configure Fine-Grain NBAR Classification Mode

The following example shows how to configure an ezPM policy using the Application Statistics profile and to force-configure fine-grain NBAR classification mode:

Device> enable
Device# configure terminal
Device(config)# performance monitor context xyz profile application-statistics
Device(config-perf-mon)# traffic-monitor application-client-server-stats
Device(config-perf-mon)# exit
Device(config)# interface gigabitEthernet 0/2/2
Device(config-if)# performance monitor context xyz
Device(config-if)# end
Device (config)# ip nbar classification granularity fine-grain

Example: Verifying the NBAR Classification Mode

The following example shows how to verify the currently configured NBAR Classification Mode:

Device # show ip nbar classification granularity

NBAR classification granularity mode: coarse-grain

Additional References for NBAR Coarse-Grain Classification

Related Documents

Related Topic

Document Title

Cisco IOS commands

Cisco IOS Master Command List, All Releases

AVC Configuration

AVC Configuration module

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.

http:/​/​www.cisco.com/​cisco/​web/​support/​index.html

Feature Information for NBAR Coarse-Grain Classification

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.
Table 1 Feature Information for NBAR Coarse-Grain Classification

Feature Name

Releases

Feature Information

NBAR Coarse-Grain Classification

Cisco IOS XE Release 3.14S

Network Based Application Recognition (NBAR) provides two levels of application recognition—coarse-grain and fine-grain. By default NBAR operates in the fine-grain mode, offering NBAR's full application recognition capabilities. By minimizing deep packet inspection, coarse-grain mode offers a performance advantage and reduces memory resource demands.

The following command was introduced or modified:

ip nbar classification granularity and show ip nbar classification granularity.