This documentation has been moved - Low Latency Queueing with Priority Percentage Support [Support]

Table Of Contents

Low Latency Queueing with Priority Percentage Support

Contents

Restrictions for LLQ with Priority Percentage Support

Information About LLQ with Priority Percentage Support

Benefits of LLQ with Priority Percentage Support

Changes to the bandwidth Command for LLQ with Priority Percentage Support

Changes to the priority Command for LLQ with Priority Percentage Support

Bandwidth Calculations in LLQ with Priority Percentage Support

How to Configure LLQ with Priority Percentage Support

Specifying the Bandwidth Percentage

Verifying the Bandwidth Percentage

Configuration Examples for LLQ with Priority Percentage Support

Example: Specifying the Bandwidth Percentage

Example: Mixing the Units of Bandwidth for Nonpriority Traffic

Example: Verifying the Bandwidth Percentage

Additional References

Related Documents

Standards

MIBs

RFCs

Technical Assistance

Feature Information for LLQ with Priority Percentage Support

Low Latency Queueing with Priority Percentage Support

First Published: February 28, 2006

Last Updated: July 31, 2008

This feature allows you to configure bandwidth as a percentage within low latency queueing (LLQ). Specifically, you can designate a percentage of the bandwidth to be allocated to an entity (such as a physical interface, a shaped ATM permanent virtual circuit (PVC), or a shaped Frame Relay PVC to which a policy map is attached). Traffic associated with the policy map will then be given priority treatment.

This feature also allows you to specify the percentage of bandwidth to be allocated to nonpriority traffic classes. It modifies two existing commands—bandwidth and priority—and provides additional functionality to the way that bandwidth can be allocated using these two commands.

Finding Feature Information in This Module

Your Cisco IOS software release may not support all of the features documented in this module. For the latest feature information and caveats, see the release notes for your platform and software release. To reach links to specific feature documentation in this module and to see a list of the releases in which each feature is supported, use the "Feature Information for LLQ with Priority Percentage Support" section.

Finding Support Information for Platforms and Cisco IOS and Catalyst OS Software Images

Use Cisco Feature Navigator to find information about platform support and Cisco IOS and Catalyst OS software image support. To access Cisco Feature Navigator, go to http://www.cisco.com/go/cfn. An account on Cisco.com is not required.

Contents

•Restrictions for LLQ with Priority Percentage Support

•Information About LLQ with Priority Percentage Support

•How to Configure LLQ with Priority Percentage Support

•Configuration Examples for LLQ with Priority Percentage Support

•Additional References

•Feature Information for LLQ with Priority Percentage Support

•Feature Information for LLQ with Priority Percentage Support

Restrictions for LLQ with Priority Percentage Support

If the incoming high priority traffic exceeds the bandwidth percentage calculated by the priority percent command, and there is congestion in the network, the excess traffic is dropped. This is identical to the behavior demonstrated when the priority command uses bandwidth in kbps. In both cases, if the high priority traffic exceeds the bandwidth, and there is congestion in the network, excess traffic is dropped.

By default, when the bandwidth percent and priority percent commands are used to allocate bandwidth, the sum of the bandwidth percentage allocated to the high priority traffic and the bandwidth percentage allocated to the nonpriority traffic cannot exceed 75 percent of the total bandwidth available on the interface.

The remaining 25 percent of the total bandwidth available on the interface is kept in reserve for the unclassified traffic and routing traffic, if any, and proportionally divided among the defined traffic classes. To override the 75 percent limitation, use the max-reserved bandwidth command in interface configuration mode.

Note The max-reserved bandwidth command is intended for use on main interfaces only; it has no effect on virtual circuits (VCs) or ATM permanent virtual circuits (PVCs).

Information About LLQ with Priority Percentage Support

To configure the Low Latency Queueing with Priority Percentage Support feature, you should understand the following concepts:

•Benefits of LLQ with Priority Percentage Support

•Changes to the bandwidth Command for LLQ with Priority Percentage Support

•Changes to the priority Command for LLQ with Priority Percentage Support

•Bandwidth Calculations in LLQ with Priority Percentage Support

Benefits of LLQ with Priority Percentage Support

This feature allows the Cisco IOS software to accommodate networks with a large number of interfaces, all with differing bandwidths. This feature is useful when all of those interfaces with differing bandwidths need to be associated with a policy map that allocates proportional bandwidths to multiple classes.

Additionally, configuring bandwidth in percentages is most useful when the underlying link bandwidth is unknown or the relative class bandwidth distributions are known. For interfaces that have adaptive shaping rates (such as available bit rate [ABR] virtual circuits), CBWFQ can be configured by configuring class bandwidths in percentages.

Changes to the bandwidth Command for LLQ with Priority Percentage Support

This feature adds a new keyword to the bandwidth command—remaining percent. The feature also changes the functionality of the existing percent keyword. These changes result in the following commands for bandwidth: bandwidth percent and bandwidth remaining percent.

The bandwidth percent command configures bandwidth as an absolute percentage of the total bandwidth on the interface.

The bandwidth remaining percent command allows you to allocate bandwidth as a relative percentage of the total bandwidth available on the interface. This command allows you to specify the relative percentage of the bandwidth to be allocated to the classes of traffic. For instance, you can specify that 30 percent of the available bandwidth be allocated to class1, and 60 percent of the bandwidth be allocated to class2. Essentially, you are specifying the ratio of the bandwidth to be allocated to the traffic class. In this case, the ratio is 1 to 2 (30 percent allocated to class1 and 60 percent allocated to class2). The sum of the numbers used to indicate this ratio cannot exceed 100 percent. This way, you need not know the total amount of bandwidth available, just the relative percentage you want to allocate for each traffic class.

Each traffic class gets a minimum bandwidth as a relative percentage of the remaining bandwidth. The remaining bandwidth is the bandwidth available after the priority queue, if present, is given its required bandwidth, and after any Resource Reservation Protocol (RSVP) flows are given their requested bandwidth.

Because this is a relative bandwidth allocation, the packets for the traffic classes are given a proportionate weight only, and no admission control is performed to determine whether any bandwidth (in kbps) is actually available. The only error checking that is performed is to ensure that the total bandwidth percentages for the classes do not exceed 100 percent.

Changes to the priority Command for LLQ with Priority Percentage Support

This feature also adds the percent keyword to the priority command. The priority percent command indicates that the bandwidth will be allocated as a percentage of the total bandwidth of the interface. You can then specify the percentage (that is, a number from 1 to 100) to be allocated by using the percentage argument with the priority percent command.

Unlike the bandwidth command, the priority command provides a strict priority to the traffic class, which ensures low latency to high priority traffic classes.

Bandwidth Calculations in LLQ with Priority Percentage Support

When the bandwidth and priority commands calculate the total amount of bandwidth available on an entity, the following guidelines are invoked:

•If the entity is a physical interface, the total bandwidth is the bandwidth on the physical interface.

•If the entity is a shaped ATM PVC, the total bandwidth is calculated as follows:

–For a variable bit rate (VBR) VC, the average shaping rate is used in the calculation.

–For an available bit rate (ABR) VC, the minimum shaping rate is used in the calculation.

•If the entity is a shaped Frame Relay PVC, the total bandwidth is calculated as follows:

–If a minimum acceptable committed information rate (minCIR) is not configured, the CIR divided by two is used in the calculation.

–If a minimum acceptable CIR is configured, the minCIR setting is used in the calculation.

How to Configure LLQ with Priority Percentage Support

Specifying the Bandwidth Percentage

SUMMARY STEPS

1. enable

2. configure terminal

3. policy-map policy-map

4. class {class-name | class-default}

5. priority {bandwidth-kbps | percent percentage} [burst]

6. bandwidth {bandwidth-kbps | percent percentage | remaining percent percentage}

7. end
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

policy-map policy-map
Example:

Router(config)# policy-map policy1

Specifies the name of the policy map to be created or modified. Enters policy-map configuration mode.

•Enter the policy map name. Names can be a maximum of 40 alphanumeric characters.

Step 4

class {class-name | class-default}
Example:

Router(config-pmap)# class class1

Specifies the class so that you can configure or modify its policy. Enters policy-map class configuration mode.

•Enter the class name.

Step 5

priority {bandwidth-kbps | percent percentage} [burst]
Example:

Router(config-pmap-c)# priority percent 10

Gives priority to a class of traffic belonging to the policy map.

•Enter the priority percentage.

Step 6

bandwidth {bandwidth-kbps | percent percentage | remaining percent percentage}
Example:

Router(config-pmap-c)# bandwidth percent 30

Specifies the bandwidth for a class of traffic belonging to the policy map.

•Enter the bandwidth percentage.
Step 7
end
Router(config-pmap-c)# end
(Optional) Exits policy-map class configuration mode and returns to privileged EXEC mode.
DETAILED STEPS

Verifying the Bandwidth Percentage

SUMMARY STEPS

1. enable

2. show policy-map policy-map

3. show policy-map policy-map class class-name

4. show policy-map interface interface type

5. 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 policy-map policy-map
Example:

Router# show policy-map policy1

(Optional) Displays the configuration of all classes for a specified service policy map or the configuration of all classes for all existing policy maps

•Enter the name of the policy map whose complete configuration is to be displayed. The name can be a maximum of 40 alphanumeric characters.

Step 3

show policy-map policy-map class class-name
Example:

Router# show policy-map policy1 class class1

(Optional) Displays the configuration for the specified class of the specified policy map.

•Enter the policy map name and the class name.

Step 4

show policy-map interface type number
Example:

Router# show policy-map interface serial4/0

(Optional) Displays the packet statistics of all classes that are configured for all service policies either on the specified interface or subinterface or on a specific PVC on the interface.

•Enter the interface type and number.

Step 5

exit
Example:

Router# exit

(Optional) Exits privileged EXEC mode.

Configuration Examples for LLQ with Priority Percentage Support

Example: Specifying the Bandwidth Percentage

The following example uses the priority percent command to specify a bandwidth percentage of 10 percent for the class called voice-percent. Then the bandwidth remaining percent command is used to specify a bandwidth percentage of 30 percent for the class called data1, and a bandwidth percentage of 20 percent for the class called data2.
Router> enable
Router# configure terminal
Router(config)# policy-map policy1
Router(config-pmap)# class voice-percent
Router(config-pmap-c)# priority percent 10
Router(config-pmap-c)# exit
Router(config-pmap)# class data1
Router(config-pmap-c)# bandwidth remaining percent 30
Router(config-pmap-c)# exit
Router(config-pmap)# class data2
Router(config-pmap-c)# bandwidth remaining percent 20
Router(config-pmap-c)# end
As a result of this configuration, 10 percent of the interface bandwidth is guaranteed for the class called voice-percent. The classes called data1 and data2 get 30 percent and 20 percent of the remaining bandwidth, respectively.

Example: Mixing the Units of Bandwidth for Nonpriority Traffic

If a particular unit (that is, kbps or percentages) is used when specifying the bandwidth for a specific class of nonpriority traffic, the same bandwidth unit must be used when specifying the bandwidth for the other nonpriority classes in that policy map. The bandwidth units within the same policy map must be identical. However, the unit for the priority command in the priority class can be different from the bandwidth unit of the nonpriority class. The same configuration can contain multiple policy maps, however, which in turn can use different bandwidth units.

The following sample configuration contains three policy maps—policy1, policy2, and policy3. In the policy map called policy1 and the policy map called policy2, the bandwidth is specified by percentage. However, in the policy map called policy3, bandwidth is specified in kbps.
Router> enable
Router# configure terminal
Router(config)# policy-map policy1
Router(config-pmap)# class voice-percent
Router(config-pmap-c)# priority percent 10
Router(config-pmap-c)# exit
Router(config-pmap)# class data1
Router(config-pmap-c)# bandwidth percent 30
Router(config-pmap-c)# exit
Router(config-pmap)# class data2
Router(config-pmap-c)# bandwidth percent 20
Router(config-pmap-c)# exit
Router(config-pmap)# exit
Router(config)# policy-map policy2
Router(config-pmap)# class voice-percent
Router(config-pmap-c)# priority percent 10
Router(config-pmap-c)# exit
Router(config-pmap)# class data1
Router(config-pmap-c)# bandwidth remaining percent 30
Router(config-pmap-c)# exit
Router(config-pmap)# class data2
Router(config-pmap-c)# bandwidth remaining percent 20
Router(config-pmap-c)# exit
Router(config-pmap)# exit
Router(config)# policy-map policy3
Router(config-pmap)# class voice-percent
Router(config-pmap-c)# priority 500
Router(config-pmap-c)# exit
Router(config-pmap)# class data1
Router(config-pmap-c)# bandwidth 30
Router(config-pmap-c)# exit
Router(config-pmap)# class data2
Router(config-pmap-c)# bandwidth 20
Router(config-pmap-c)# end
Example: Verifying the Bandwidth Percentage

The following sample output from the show policy-map interface command shows that 50 percent of the interface bandwidth is guaranteed for the class called class1, and 25 percent is guaranteed for the class called class2. The output displays the amount of bandwidth as both a percentage and a number of kbps.
Router# show policy-map interface serial3/2
 Serial3/2
  Service-policy output:policy1
    Class-map:class1 (match-all)
      0 packets, 0 bytes
      5 minute offered rate 0 bps, drop rate 0 bps
      Match:none
      Weighted Fair Queueing
        Output Queue:Conversation 265
        Bandwidth 50 (%)
        Bandwidth 772 (kbps) Max Threshold 64 (packets)
        (pkts matched/bytes matched) 0/0
        (depth/total drops/no-buffer drops) 0/0/0
Class-map:class2 (match-all)
      0 packets, 0 bytes
      5 minute offered rate 0 bps, drop rate 0 bps
      Match:none
      Weighted Fair Queueing
        Output Queue:Conversation 266
        Bandwidth 25 (%)
        Bandwidth 386 (kbps) Max Threshold 64 (packets)
        (pkts matched/bytes matched) 0/0
        (depth/total drops/no-buffer drops) 0/0/0
    Class-map:class-default (match-any)
      0 packets, 0 bytes
      5 minute offered rate 0 bps, drop rate 0 bps
      Match:any
In this example, interface s3/2 has a total bandwidth of 1544 kbps. During periods of congestion, 50 percent (or 772 kbps) of the bandwidth is guaranteed to the class called class1, and 25 percent (or 386 kbps) of the link bandwidth is guaranteed to the class called class2.

Note The counters displayed for classes configured with bandwidth or priority after using the show policy-map interface command are updated only if congestion is present on the interface.

Additional References

The following sections provide references related to the Low Latency Queueing with Priority Percentage Support feature.

Related Documents

Related Topic

Document Title

QoS commands: complete command syntax, command modes, command history, defaults, usage guidelines, and examples

Cisco IOS Quality of Service Solutions Command Reference

Congestion management concepts and related topics

"Congestion Management Overview" module

LLQ, bandwidth allocation

"Configuring Weighted Fair Queueing" module

Standards

Standards

Title

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

—

MIBs

MIBs

MIBs Link

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

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

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

RFCs

RFCs

Title

No new or modified RFCs are supported, and support for existing RFCs has not been modified.

—

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 LLQ with Priority Percentage Support

Table 1 lists the release history for this feature.

Not all commands may be available in your Cisco IOS software release. For release information about a specific command, see the command reference documentation.

Use Cisco Feature Navigator to find information about platform support and software image support. Cisco Feature Navigator enables you to determine which Cisco IOS and Catalyst OS software images support a specific software release, feature set, or platform. To access Cisco Feature Navigator, go to http://www.cisco.com/go/cfn. An account on Cisco.com is not required.

Note Table 1 lists only the Cisco IOS software release that introduced support for a given feature in a given Cisco IOS software release train. Unless noted otherwise, subsequent releases of that Cisco IOS software release train also support that feature.

Table 1 Feature Information for Low Latency Queueing with Priority Percentage Support

Feature Name

Releases

Feature Information

Low Latency Queueing with Priority Percentage Support

12.2(2)T
12.0(28)S
12.2(28)SB

This feature allows you to configure bandwidth as a percentage within low latency queueing (LLQ). Specifically, you can designate a percentage of the bandwidth to be allocated to an entity (such as a physical interface, a shaped ATM permanent virtual circuit (PVC), or a shaped Frame Relay PVC to which a policy map is attached). Traffic associated with the policy map will then be given priority treatment.

In 12.2(2)T, this feature was introduced.

In 12.0(28)S, this feature was integrated into Cisco IOS Release 12.0(28)S.

In 12.2(28)SB, this feature was integrated into Cisco IOS Release 12.2(28)SB.

The following commands were introduced or modified: bandwidth (policy-map class), priority.

Cisco and the Cisco Logo are trademarks of Cisco Systems, Inc. and/or its affiliates in the U.S. and other countries. A listing of Cisco's trademarks can be found at www.cisco.com/go/trademarks. Third party trademarks mentioned are the property of their respective owners. The use of the word partner does not imply a partnership relationship between Cisco and any other company. (1005R)

Any Internet Protocol (IP) addresses and phone numbers used in this document are not intended to be actual addresses and phone numbers. Any examples, command display output, network topology diagrams, and other figures included in the document are shown for illustrative purposes only. Any use of actual IP addresses or phone numbers in illustrative content is unintentional and coincidental.

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