CBQoS MIB Index Enhancements

The Class-Based Quality of Service (CBQoS) MIB Index Enhancements feature introduces persistence across all CBQoS MIB indexes including cbQosConfigIndex, cbQosObjectsIndex, and cbQosPolicyIndex.

Finding Feature Information

Your software release may not support all the features documented in this module. For the latest caveats and feature information, see Bug Search Tool and the release notes for your platform and software release. To find information about the features documented in this module, and to see a list of the releases in which each feature is supported, see the feature information table.

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.

Prerequisites for the QoS CBQoS MIB Index Enhancements

You must enable ifMIB persistence by issuing the snmp-server ifindex persist command. Then issue the snmp mib persist cbqos command to enable CBQoS MIB index persistence.


Note

If you issue the snmp mib persist cbqos command before the snmp-server ifindex persist command, you receive a prompt requesting you to enable ifIndex persistence first.

Restrictions for the CBQoS MIB Index Enhancements

If the internal hashing of configuration strings causes too many collisions, NVRAM storage may become tight. You can issue the more nvram command to display a new collision file called cbqos-mib to help you keep track of the size.

Information About the CBQoS MIB Index Enhancements

Feature Overview of the QoS CBQoS MIB Index Enhancements

The cbQosConfigIndex, cbQosObjectsIndex, and cbQosPolicyIndex are volatile because when a networking device reboots, the index numbers may change. This happens because system rebooting can cause the order of the Modular QoS CLI (MQC) configuration to differ from the actual configuration order, which is user-driven and unpredictable. As a result, you must read the MIB frequently to extract statistical and configuration information. Therefore, once a reload has occurred, the MIB has to be repolled to reestablish the indexes to the data stored in the CBQoS MIB.

Traditionally, MIB persistence is handled by Cisco IOS APIs, which save the index and key information to NVRAM. The data is then retrieved and repopulated after reloading. However, this approach does not work well for the current implementation of the cbQosObjectsIndex because of the large amount of information that needs to be saved.

An index encoding scheme based on configuration entries instead of operational sequence is being implemented to provide persistent indexes on router reload so that MIB information retains the same set of object values each time that a networking device reboots.

The index encoding scheme has been changed to handle the performance/scalability issue. Each service policy is uniquely identified by an index called cbQosPolicyIndex, and its cbQosObjectsIndex is uniquely identified under the service policy.


Note

As a result of this change in the index encoding scheme, an application must not assume that the cbQosPolicyIndex is usually identical to its cbQosObjectsIndex as a policy-map.

Benefits of the QoS CBQoS MIB Index Enhancements

These enhancements provide a repeatable method for generating MIB indexes so that they do not change between reboots.

The complexity of configuring and correlating statistics objects is reduced, making it easier for network management applications to gather accurate information.

How to Configure the CBQoS MIB Index Enhancements

Enabling Cisco IOS MIB and CBQoS MIB Index Persistence

SUMMARY STEPS

  1. enable
  2. configure terminal
  3. snmp-server ifindex persist
  4. snmp mib persist [cbqos | v3mibs ]
  5. end
  6. write mib-data

DETAILED STEPS

  Command or Action Purpose
Step 1

enable

Example:


Router> enable

Enables privileged EXEC mode.

  • Enter your password if prompted.

Step 2

configure terminal

Example:


Router# configure terminal

Enters global configuration mode.

Step 3

snmp-server ifindex persist

Example:


Router(config)# snmp-server ifindex persist

Enables Cisco IOS MIB index (ifIndex) persistence.

Step 4

snmp mib persist [cbqos | v3mibs ]

Example:


Router(config)# snmp mib persist cbqos

Enables MIB persistence.

  • The optional cbqos keyword enables CBQoS MIB persistence.

  • The optional v3mibs keyword enables v3 MIB persistence.

Note 

If you have not enabled Cisco IOS MIB index (ifIndex) persistence (Step 3), the following message appears when you issue the snmp mib persist cbqos command: Enable 'snmp-server ifindex persist' for persist cbqos index

Step 5

end

Example:


Router(config)# end

Returns to privileged EXEC mode.

Step 6

write mib-data

Example:


            
              write

Example:


Router# write mib-data

Example:


Router# write

Saves CBQoS MIB data to NVRAM.

Verifying CBQoS MIB Index Persistence

SUMMARY STEPS

  1. enable
  2. show running-config include cbqos
  3. exit

DETAILED STEPS

  Command or Action Purpose
Step 1

enable

Example:


Router> enable

Enables privileged EXEC mode.

  • Enter your password if prompted.

Step 2

show running-config include cbqos

Example:


Router# show running-config | include cbqos

Displays the configuration information currently running on the router.

Note 

The information should include snmp mib persist cbqos.

Step 3

exit

Example:


Router# exit

Returns to user EXEC mode.

Configuration Examples for the CBQoS MIB Index Enhancements

Example Enabling Cisco IOS MIB and CBQoS MIB Index Persistence

The following example enables Cisco IOS MIB (ifIndex) and CBQoS MIB index persistence: 


Router# configure terminal
Enter configuration commands, one per line.  End with CNTL/Z.
Router(config)# snmp-server ifindex persist
Router(config)# snmp mib persist cbqos

Examples Verifying Cisco IOS MIB and CBQoS MIB Index Persistence

The following examples verify that Cisco IOS MIB (ifIndex) and CBQoS MIB index persistence have been configured: 


Router# show running-config 
| include cbqos
snmp mib persist cbqos
Router# show running-config 
| include persist
snmp-server ifindex persist
snmp mib persist cbqos

Additional References

Related Documents

Related Topic

Document Title

QoS commands

Cisco IOS Quality of Service Solutions Command Reference

SNMP commands

Cisco IOS Network Management Command Reference

SNMP configuration tasks, MIB persistence

"Configuring SNMP Support" module

Other documentation

For information on using SNMP MIB features, see the appropriate documentation for your network management system.

Standards

Standard

Title

No new or modified standards are supported by this feature, and support for existing standards has not been modified by this feature.

--

MIBs

MIB

MIBs Link

CISCO-CLASS-BASED-QOS-MIB, Revision 13

Note 

The CISCO-CLASS-BASED-QOS-MIB is actually two MIBs: the CISCO-CLASS-BASED-QOS-MIB and the CISCO-CLASS-BASED-QOS-CAPABILITY-MIB.

To locate and download MIBs for selected platforms, Cisco IOS XE software releases, and feature sets, use Cisco MIB Locator found at the following URL:

http://www.cisco.com/go/mibs

RFCs

RFC

Title

RFC 2233

The Interfaces Group MIB Using SMIv2

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 the QoS CBQoS MIB Index Enhancements

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 the QoS CBQoS MIB Index Enhancements

Feature Name

Releases

Feature Information

QoS CBQoS MIB Index Enhancements

Cisco IOS XE Release 2.4

The CBQoS MIB Index Enhancements feature introduces persistence across all CBQoS MIB indexes including cbQosConfigIndex, cbQosObjectsIndex, and cbQosPolicyIndex.