QoS: DiffServ for Quality of Service Overview Configuration Guide, Cisco IOS XE 17
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The DiffServ MIB is used to poll already configured information and statistics from the devices on which is it enabled.
Network service providers that deliver differentiated services to their customer must be able to configure and monitor routers
in order to satisfy Service Level Agreements (SLAs). DiffServ is a protocol that allows the network service provider to use
classes to control network traffic so that certain types of traffic get precedence. For example, voice traffic requires a
relatively uninterrupted flow of data, and might get precedence over other kinds of traffic, such as e-mail. DiffServ can
be offered to customers as a way to distinguish between various levels of service; for example, Premium, Gold, Silver, and
Bronze. Therefore, SLAs and DiffServ technologies are closely linked.
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.
Information About DiffServ MIB
Restrictions for DiffServ MIB
DiffServ MIB will not support the configurations described in this section even if the user has configured them through Modular
QoS CLI (MQC) and they are functioning in the forwarding path.
Note
The restrictions do not result in configurations being rejected, because Diffserv MIB is not exposed to the unsupported configurations.
DiffServ MIB provides the ability to read Simple Network Management Protocol (SNMP) requests only; it cannot be used to perform
any provisioning tasks.
Multiple filters in the same class-map definition are not supported. Therefore, in supported class maps that contain only
one filter definition, match-any and match-all types are irrelevant.
Note
Class maps with one Access Control List (ACL) and that contain multiple Cisco Application Control Engines (ACEs) are supported.
Class maps with one Differentiated Services Code Point (DSCP) filter that takes multiple DSCP values as part of one match
criterion also are supported. However, match-not types are not supported.
Fair queueing is not supported.
Marking is not supported in the parent class of hierarchical policy.
Policing in the parent class is not supported if queueing is configured in the child class.
For priority and bandwidth feature configurations, the related table is populated with either kbps or relative percentage
values only.
Default values are not populated into the MIB tables.
Note
The classifier table does include defined defaults for address, port, and related fields.
Random-detect functionality is not supported in the parent class of a hierarchical policy.
Only child first (bottom-up) policing is supported in hierarchical policies.
Any fields not supported by the current routing platform will contain the value 0, or some appropriate default value. For
example, the Cisco ASR1000 Series Aggregation Services Routers do not support policer color-aware statistics, so fields related
to these statistics will be set to 0 on those routers.
MQC and DiffServ MIB
Most Cisco products use the Modular QoS CLI (MQC) to support the provisioning of industry-standard Differentiated Services
Architecture services. However, the industry standard for the provisioning of differentiated services (DiffServ MIB) differs
from the MQC implementation. The DiffServ MIB feature is implemented on top of the MQC functionality and translates service
provisioning instructions from the DiffServ MIB to MQC.
By implementing DiffServ MIB on top of the MQC provisioning language, MQC can still be used to enable QoS policies in Cisco
products. In addition, Cisco products that support MQC already support direct mapping of actions between the cbQoSMIB and
MQC. The cbQoSMIB is the Cisco recommended MIB. Implementation of DiffServ MIB does not replace the cbQoSMIB.
The Diffserv MIB feature maps each field in a set of tables defined in the DiffServ MIB RFC to an MQC supported action (where
an action is available).
Hierarchical Policies and DiffServ MIB
For hierarchical policies the Modular QoS CLI (MQC) runs all classification instructions first, from the top of the hierarchy
to the bottom of the hierarchy. It then performs feature execution in the following order: marking (top to bottom), policing
(bottom to top), and queueing (bottom to top).
To translate the MQC implementation of a hierarchical policy to a DiffServ MIB implementation, the hierarchy must be separated
into different chained functional blocks that determine the execution order of the features.
Note
Not all feature combinations from an MQC hierarchy are supported in the DiffServ MIB. For more information see the "Restrictions
for DiffServ MIB" section.
How to Configure DiffServ MIB
Enabling DiffServ MIB
SUMMARY STEPS
enable
configureterminal
qosdiffservmib
end
DETAILED STEPS
Command or Action
Purpose
Step 1
enable
Example:
Device> enable
Enables privileged EXEC mode.
Enter your password if prompted.
Step 2
configureterminal
Example:
Device# configure terminal
Enters global configuration mode.
Step 3
qosdiffservmib
Example:
Device(config)# qos diffservmib
Enables DiffServ MIB support for quality of service (QoS) policy maps.
Step 4
end
Example:
Device(config)# end
(Optional) Returns to privileged EXEC mode.
Configuration Examples for DiffServ MIB
Example: Enabling DiffServ MIB
The following example shows how to enable DiffServ MIB support for Quality of Service (QoS) policy maps:
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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 DiffServ MIB
Feature Name
Releases
Feature Information
DiffServ MIB
15.3(1)T
This feature provides support for QoS Diffserv MIB (RFC 3289).
The following command was introduced or modified:
qos diffservmib.
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