- Congestion Management Overview
- IPv6 QoS: Queueing
- Low Latency Queueing with Priority Percentage Support
- Low Latency Queueing for IPsec Encryption Engines
- Configurable Queue Depth
- Multi-Level Priority Queues
- Configuring Custom Queueing
- QoS Hierarchical Queueing for Ethernet DSLAMs
- QoS Hierarchical Queueing for ATM DSLAMs
- Per-Flow Admission
- Finding Feature Information
- 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
Low Latency Queueing with Priority Percentage Support
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
- 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
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.
Restrictions for LLQ with Priority Percentage Support
Dropping Excess Traffic
If the incoming high priority traffic exceeds the bandwidth percentage calculated by the priority percentcommand, and there is congestion in the network, the excess traffic is dropped. This is identical to the behavior demonstrated when the prioritycommand 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.
Exceeding the Configured Bandwidth Percentage Calculated by the bandwidth percent and priority percent Commands
By default, when the bandwidth percentand 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 99 percent of the total bandwidth available on the interface.
The remaining 1 percent of the total bandwidth available on the interface is kept in reserve for the unclassified traffic and routing traffic, if any, and is proportionally divided among the defined traffic classes.
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
Benefits of LLQ with Priority Percentage Support
This feature allows the Cisco 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 percentand bandwidth remaining percent.
The bandwidth percent command configures bandwidth as an absolute percentage of the total bandwidth on the interface.
The bandwidth remaining percentcommand 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 percentcommand.
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.
How to Configure LLQ with Priority Percentage Support
Specifying the Bandwidth Percentage
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
DETAILED STEPS
Verifying the Bandwidth Percentage
1.
enable
2.
show
policy-map
policy-map
3.
show
policy-map
policy-map
class
class-name
4.
show
policy-map
interface
type
number
5.
exit
DETAILED STEPS
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
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 interfacecommand shows that 50 percent of the interface bandwidth is guaranteed for the class called class1 and that 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 serial3/2/0 Serial3/2/0 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, serial interface s3/2/0 has a total bandwidth of 1544 kbps. During periods of congestion, 50 percent (or 772 kbps) of the link 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.
Additional References
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 |
LLQ |
"Applying QoS Features Using the MQC" module |
Standards
Standards |
Title |
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No new or modified standards are supported, and support for existing standards has not been modified. |
-- |
MIBs
MIBs |
MIBs Link |
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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 XE Software releases, and feature sets, use Cisco MIB Locator found at the following URL: |
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. |
Feature Information for LLQ with Priority Percentage Support
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.
Feature Name |
Releases |
Feature Information |
---|---|---|
Low Latency Queueing with Priority Percentage Support |
Cisco IOS XE Release 2.1 |
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 was implemented on the Cisco ASR 1000 Series Routers. The following commands were introduced or modified: bandwidth(policy-map class), priority. |