ATM Hierarchical Shaping—ATM VC into VP Shaping

First Published: March 18, 2011
Last Updated: March 18, 2011

Traffic shaping is a quality of service (QoS) mechanism that is used to manage the network traffic by shaping the traffic to a specified rate. Traffic shaping enables the network administrator to:

•Control access to the available bandwidth.

•Ensure that the traffic conforms to the policies.

•Regulate the flow of traffic to avoid congestion that can occur when the transmitted traffic exceeds the access speed of its remote target interface.

Traffic shaping uses queues to constrain data bursts, limit peak data rate, and smooth jitters so that traffic will fit within the promised envelope. Traffic shaping limits the throughput by buffering excess traffic instead of dropping packets.

ATM VP/VC hierarchical shaping provides two levels of traffic shaping—per-VC and per-VP—to control or modify the flow of traffic on an interface. The shaping function also ensures that the traffic from one VC does not adversely impact another VC, thus preventing the loss of data. The traffic is shaped first at the VC level and then at the VP level.

Finding Feature Information

Your software release may not support all the features documented in this module. For the latest feature information and caveats, see 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 for ATM Hierarchical Shaping" section.

Use Cisco Feature Navigator to find information about platform support and Cisco 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 ATM Hierarchical Shaping

•Information About ATM Hierarchical Shaping

•How to Configure ATM Hierarchical Shaping

•Configuration Examples for ATM Hierarchical Shaping

•Additional References

•Feature Information for ATM Hierarchical Shaping

Restrictions for ATM Hierarchical Shaping

All virtual channels (VCs) within a given virtual path (VP) must belong to the same ATM service category.

Information About ATM Hierarchical Shaping

•ATM Hierarchical Shaping

ATM Hierarchical Shaping

If a service (or an application) wants to use an ATM network to transport a particular kind of traffic, it must first inform the network about what kind of traffic is to be transported, and the performance requirements of that traffic. The ATM service categories provide a method to relate traffic characteristics and QoS requirements to network behavior. Hierarchical shaping requires that all VCs belonging to a given VP have the same ATM service category. This hierarchy ensures that packets are shaped first at the VC level and then at the VP level. At the interface level, the priority is based on the ATM service category. The service category is determined by the first PVC that is configured under a VP. The priority is in the following order:

1. Constant Bit Rate (CBR)

2. Unspecified Bit Rate (UBR)

3. Variable Bit Rate Non Real-Time (VBR-nRT)

4. Real-time Variable Bit Rate (VBR-RT)

If no service category is specified at the VC level, the default is unshaped UBR. The ATM Hierarchical Shaping feature is supported for the following ATM traffic service categories:

•VBR-nRT

•UBR

For VBR-nRT traffic the output sustainable cell rate (SCR) value that is configured will be taken into account for VC shaping. For UBR traffic, the output peak cell rate (PCR) value that is configured will be taken into account for VC shaping.

The ATM Hierarchical Shaping feature supports over-subscription. Over-subscription occurs when the sum of the configured rate of UBR and VBR PVCs exceeds the line rate.

How to Configure ATM Hierarchical Shaping

•Configuring ATM Hierarchical Shaping (required)

Configuring ATM Hierarchical Shaping

Perform this task to configure ATM hierarchical shaping.

SUMMARY STEPS

1. enable

2. configure terminal

3. interface atm interface-number [.subinterface-number {mpls | multipoint | point-to-point}]

4. atm pvp vpi [peak-rate]

5. pvc vpi/vci

6. exit

7. range [range-name] pvc [start-vpi/]start-vci [end-vpi/]end-vci

8. ubr output-pcr

9. exit

10. atm pvp vpi [peak-rate]

11. pvc vpi/vci

12. vbr-nrt output-pcr output-scr [output-maxburstsize]

13. create on-demand

14. end

15. show atm pvc

16. show atm vp

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 

interface atm interface-number [.subinterface-number {mpls | multipoint | point-to-point}]

Example:

Router(config)# interface atm 0/3/2.1 multipoint

Configure an ATM interface and enters subinterface configuration mode.

Step 4 

atm pvp vpi [peak-rate]

Example:

Router(config-subif)# atm pvp 2

Creates a permanent virtual path (PVP) used to multiplex (or bundle) one or more VCs.

Step 5 

pvc vpi/vci

Example:

Router(config-subif)# pvc 2/200

Creates or assigns a name to an ATM PVC and enters ATM virtual circuit configuration mode.

Step 6 

exit

Example:

Router(config-if-atm-vc)# exit

Exits ATM virtual circuit configuration mode and returns to subinterface configuration mode.

Step 7 

range [range-name] pvc [start-vpi/]start-vci [end-vpi/]end-vci

Example:

Router(config-subif)# range range1 pvc 2/100 2/102

Defines a range of ATM PVCs.

Step 8 

ubr output-pcr

Example:

Router(config-if-atm-vc)# ubr 4000

Configures UBR QoS and specifies the output PCR for an ATM PVC, PVC range, switched virtual circuit (SVC), VC class, or VC bundle member.

Step 9 

exit

Example:

Router(config-if-atm-vc)# exit

Exits ATM virtual circuit configuration mode and returns to subinterface configuration mode.

Step 10 

atm pvp vpi [peak-rate]

Example:

Router(config-subif)# atm pvp 3

Creates a PVP used to multiplex (or bundle) one or more VCs.

Step 11 

pvc vpi/vci

Example:

Router(config-subif)# pvc 3/150

Creates or assigns a name to an ATM PVC and enters ATM virtual circuit configuration mode.

Step 12 

vbr-nrt output-pcr output-scr [output-maxburstsize]

Example:

Router(config-if-atm-vc)# vbr-nrt 1000 1000

Configures the VBR-nRT QoS and specifies output PCR, output SCR, and output maximum burst cell size for an ATM PVC, PVC range, SVC, VC class, or VC bundle member.

Step 13 

create on-demand

Example:

Router(config-if-atm-vc)# create on-demand

Configures ATM PVC autoprovisioning, which enables a PVC or range of PVCs to be created automatically on demand.

Step 14 

end

Example:

Router(config-if-atm-vc)# end

Exits ATM virtual circuit configuration mode and returns to privileged EXEC mode.

Step 15 

show atm pvc

Example:

Router# show atm pvc

(Optional) Displays the statistics for all VPs on an interface or for a specific VP.

Step 16 

show atm vp

Example:

Router# show atm vp

(Optional) Displays all ATM PVCs and traffic information.

Configuration Examples for ATM Hierarchical Shaping

•Example: Configuring ATM Hierarchical Shaping

Example: Configuring ATM Hierarchical Shaping

The following example shows how to configure ATM hierarchical shaping: 

enable

 configure terminal

  interface atm 0/3/2.1 multipoint

   atm pvp 2

   pvc 2/200

    exit

   range range1 pvc 2/100 2/102

    ubr 4000

    exit

   atm pvp 3

   pvc 3/100

    vbr-nrt 1000 1000

    create on-demand

    end

Additional References

Related Documents

Related Topic
Document Title

Cisco IOS commands

Cisco IOS Master Commands List, All Releases

ATM commands

Cisco IOS Asynchronous Transfer Mode Command Reference


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

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

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

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


RFCs

RFC
Title

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

—


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 ATM Hierarchical Shaping

Table 1 lists the release history for this feature.

Use Cisco Feature Navigator to find information about platform support and software image support. Cisco Feature Navigator enables you to determine which 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 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.

Table 1 Feature Information for ATM Hierarchical Shaping

Feature Name
Releases
Feature Information

ATM Hierarchical Shaping—ATM VC into VP Shaping

Cisco IOS XE Release 3.3S

ATM VP/VC hierarchical shaping provides two levels of traffic shaping—per-VC and per-VP—to control or modify the flow of traffic on an interface. The shaping function also ensures that traffic from one VC does not adversely impact another VC, thus preventing loss of data. The traffic is shaped first at the VC level and then at the VP level.


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.

© 2011 Cisco Systems, Inc. All rights reserved.