Asynchronous Transfer Mode Configuration Guide, Cisco IOS XE Release 3S (Cisco ASR 1000)
ATM Hierarchical Shaping ATM VC into VP Shaping
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ATM Hierarchical Shaping ATM VC into VP Shaping

ATM Hierarchical Shaping ATM VC into VP Shaping

Last Updated: October 30, 2012

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 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 at the end of this module.

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 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

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

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

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

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 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.

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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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