Cisco IOS Software Releases 12.2 T

Table Of Contents

Configuration Enhancements for Broadband Scalability

Contents

Feature Overview

Virtual Access Subinterfaces

Virtual Template Compatibility with Subinterfaces

Benefits

Restrictions

Configuration Tasks

Verifying Virtual Template Compatibility with Virtual Access Subinterfaces

Configuration Examples

Virtual Access Subinterface Configuration: Example

Testing a Virtual Template for Compatibility with Subinterfaces: Example

Additional References

Related Documents

Standards

MIBs

RFCs

Technical Assistance

Command Reference

debug vtemplate subinterface

test virtual-template subinterface

virtual-template subinterface

Configuration Enhancements for Broadband Scalability

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First Published: November 25, 2002

Last Updated: February 28, 2006

The Configuration Enhancements for Broadband Scalability feature reduces the amount of memory that is used per terminated PPP session by creating virtual access subinterfaces. Depending on the configuration of the source virtual template, virtual access subinterfaces may be available. This feature also introduces a command to determine if a virtual template is compatible with virtual access subinterfaces.

History for the Configuration Enhancements for Broadband Scalability Feature

Release	Modification
12.2(13)T	This feature was introduced.
12.2(15)B	This feature was integrated into Cisco IOS Release 12.2(15)B.
12.2(28)SB	This feature was integrated into Cisco IOS Release 12.2(28)SB.

Finding Support Information for Platforms and Cisco IOS Software Images

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Contents

•Feature Overview

•Benefits

•Restrictions

•Configuration Tasks

•Configuration Examples

•Additional References

•Command Reference

Feature Overview

The following sections describe the use of virtual access subinterfaces:

•Virtual Access Subinterfaces

•Virtual Template Compatibility with Subinterfaces

Virtual Access Subinterfaces

The virtual-template command has not been changed. Therefore, existing features, functions, and configurations are not affected. By default, the virtual-template subinterface command is enabled.

The virtual template manager will determine if the set of options configured on the virtual template are all supported on a subinterface. Virtual access subinterfaces will be created for all virtual templates that support subinterfaces. If the user has entered any commands that are not supported on a subinterface, a full virtual access interface will be created and cloned for all PPP sessions using that virtual template. If the virtual-template subinterface command is disabled, full virtual access interfaces will always be created.

Different applications can use the same virtual template even if one application is subinterface-capable and another is not. The virtual template manager will be notified whether the application supports virtual access subinterfaces and create the appropriate resource.

The ppp multilink and ppp callback accept commands will not necessarily prevent subinterfaces from being created. Often, these commands are present in a virtual template configuration, but PPP does not negotiate them. If neither of these features is negotiated, virtual access subinterfaces will be created. If one or both of these features is negotiated, subinterfaces will not be created. The router will automatically determine if subinterfaces will be created depending on how PPP is negotiated on a case- by-case basis.

Virtual Template Compatibility with Subinterfaces

The test virtual-template subinterface command determines whether a virtual template can support the creation of a virtual access subinterface. If the virtual template contains commands that prevent the creation of subinterfaces, the test virtual-template subinterface command identifies and displays these commands.

If the creation of virtual access subinterfaces is disabled by the no virtual-template subinterface command, the test virtual-template subinterface command produces no output.

The debug vtemplate subinterface command is introduced to display new debug messages that will be generated if the user enters configuration commands on the virtual template that are not valid on a subinterface. These messages will be generated only if the debug vtemplate subinterface command is enabled, the virtual-template subinterface command is enabled, and a virtual template is configured that can support the creation of subinterfaces. If the creation of virtual access subinterfaces is disabled by the no virtual-template subinterface command, the debug vtemplate subinterface command produces no output.

Benefits

The Configuration Enhancements for Broadband Scalability feature reduces the amount of memory that is used per terminated PPP session by creating virtual access subinterfaces. These virtual access subinterfaces, along with improvements that are transparent to the user, speed up the cloning process.

Restrictions

This feature is not intended to improve the scalability of the following features:

•Scaling for dial-out

•Scaling for PPP callback

•Scaling virtual profiles

•Scaling Multilink PPP (MLP)

•PPP over X (PPPoX) applications that terminate PPP on physical interfaces

Configuration Tasks

To configure a router to always create full virtual access interfaces instead of virtual access subinterfaces, use the following commands beginning in privileged EXEC mode:

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Note The virtual-template subinterface command is enabled by default and does not appear in the running configuration.

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	Command	Purpose
Step 1	Router# configure terminal	Enters global configuration mode.
Step 2	Router# no virtual-template subinterface	Disables the creation of virtual access subinterfaces. Note The virtual-template subinterface command is enabled by default.

Verifying Virtual Template Compatibility with Virtual Access Subinterfaces

To test a virtual template to determine if it is compatible with the creation of virtual access subinterfaces, use the following commands beginning in privileged EXEC mode:

	Command	Purpose
Step 1	Router# test virtual-template template subinterface Subinterfaces cannot be created using Virtual-Template1 Interface commands: traffic-shape rate 50000 8000 8000 1000	Tests the specified virtual template to determine if it is compatible with the creation of virtual access subinterfaces. The output generated by the test virtual-template 1 subinterface command describes the compatibility of the virtual template with the creation of subinterfaces. This example shows output indicating that the virtual template is not compatible. This output also includes a list of the commands that are configured on the virtual template and that are causing the incompatibility.

Configuration Examples

This section provides the following configuration examples:

•Virtual Access Subinterface Configuration: Example

•Testing a Virtual Template for Compatibility with Subinterfaces: Example

Virtual Access Subinterface Configuration: Example

The following example shows a virtual template that is compatible with virtual access subinterfaces:

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Note The virtual-access subinterface command is enabled by default and does not appear in running configurations. Only the no virtual-access subinterface command will appear in running configurations.

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interface Virtual-Template1

  ip unnumbered Loopback0

peer default ip address pool pool-1

  ppp authentication chap

  ppp multilink

The following example shows a configuration where the creation of virtual access subinterfaces has been disabled by the no virtual-access subinterface command. When this command is configured, virtual-access interfaces are not registered with the SNMP code on the router. In network environments that do not use SNMP to manage PPP sessions, this saves the memory and CPU processing that would be used to register the virtual-access interfaces with the SNMP code.

Current configuration :6003 bytes

!

! Last configuration change at 10:59:02 EDT Thu Sep 19 2002

!

version 12.2

service timestamps debug datetime msec

service timestamps log datetime msec

no service password-encryption

service internal

service udp-small-servers

service tcp-small-servers

!

hostname ioswan5-lns

!

enable password lab

!

username cisco password 0 cisco

clock timezone EST -5

clock summer-time EDT recurring

aaa new-model

!

!

aaa authentication ppp default local

aaa authorization network default local 

aaa session-id common

ip subnet-zero

no ip gratuitous-arps

ip cef

!

!

no ip domain lookup

ip name-server 10.44.11.21

ip name-server 10.44.11.206

!

ip vrf vpn1

 rd 10:1

 route-target export 10:1

 route-target import 10:1

!

vpdn enable

!

vpdn-group 1

 accept-dialin

  protocol l2tp

  virtual-template 1

 terminate-from hostname ioswan5-lac

 local name tunnel1

 l2tp tunnel password 7 01100F175804

!

!

!

no virtual-template subinterface

no virtual-template snmp

virtual-template 1 pre-clone 10

!         

! 

!         

buffers small permanent 20000

buffers middle permanent 7500

!         

!         

!         

interface Loopback1

 ip address 10.111.1.1 255.255.255.0

Testing a Virtual Template for Compatibility with Subinterfaces: Example

This example shows the process for testing a virtual template to determine if it can support virtual access subinterfaces. The following command displays the configuration for virtual template 1:

Router# show running interface virtual-template 1

Building configuration...

!

interface Virtual-Template1

 ip unnumbered Loopback0

 peer default ip address pool pool-1

 ppp authentication chap

 traffic-shape rate 50000 8000 8000 1000

end

The test virtual-template 1 subinterface command tests virtual template 1 to determine if it can support subinterfaces. The output shows that the traffic-shape rate 50000 8000 8000 1000 command that is configured on virtual template 1 prevents the virtual template from being able to support subinterfaces.

Router# test virtual-template 1 subinterface

Subinterfaces cannot be created using Virtual-Template1

Interface commands:

 traffic-shape rate 50000 8000 8000 1000

Additional References

The following sections provide references related to the Configuration Enhancements for Broadband Scalability feature.

Related Documents

Related Topic	Document Title
Virtual templates	"Configuring Virtual Template Interfaces" chapter in the Cisco IOS Dial Technologies Configuration Guide, Release 12.4
Virtual profiles	"Configuring Virtual Profiles" chapter in the Cisco IOS Dial Technologies Configuration Guide, Release 12.4

Standards

Standard	Title
None	—

MIBs

MIB	MIBs Link
None	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

RFC	Title
None	—

Technical Assistance

Description	Link
The Cisco Technical Support & Documentation website contains thousands of pages of searchable technical content, including links to products, technologies, solutions, technical tips, and tools. Registered Cisco.com users can log in from this page to access even more content.	http://www.cisco.com/techsupport

Command Reference

This section documents modified commands only.

•debug vtemplate subinterface

•test virtual-template subinterface

•virtual-template subinterface

debug vtemplate subinterface

To display debugging messages relating to virtual access subinterfaces, use the debug vtemplate subinterface command in privileged EXEC mode. To disable debugging output, use the no form of this command.

debug vtemplate subinterface

no debug vtemplate subinterface

Syntax Description

This command has no arguments or keywords.

Defaults

No default behavior or values.

Command Modes

Privileged EXEC

Command History

Release	Modification
12.2(8)B	This command was introduced.
12.2(13)T	The command was integrated into Cisco IOS Release 12.2(13)T.
12.2(15)T	This command was integrated into Cisco IOS Release 12.2(15)T.
12.2(28)SB	This command was integrated into Cisco IOS Release 12.2(28)SB.

Usage Guidelines

These debugging messages are displayed if the user configures virtual templates with commands that are incompatible with virtual access subinterfaces.

Examples

The following example displays virtual access subinterface debugging messages:

Router# debug vtemplate subinterface

Virtual Template subinterface debugging is on

Router#

Router#

Sep 19 15:09:41.989:VT[Vt11]:Config prevents subinterface creation

 carrier-delay 45

 ip rtp priority 2000 2010 500

Table 1 describes the significant fields shown in the display.

Table 1 debug vtemplate subinterface Field Descriptions 

Field	Description
VT	Indicates that this is a debug virtual template subinterface message.
[Vt11]:	Indicates that this message concerns virtual template 11.
Config prevents subinterface creation	Indicates that this virtual template cannot support the creation of virtual access subinterfaces.
carrier-delay 45 ip rtp priority 2000 2010 500	These are the commands that make the virtual template incompatible with subinterfaces.

Related Commands

Command	Description
test virtual-template subinterface	Tests a virtual template to determine if it can support virtual access subinterfaces.
virtual-template subinterface	Enables the creation of virtual access subinterfaces.

test virtual-template subinterface

To determine if a virtual template can support the creation of subinterfaces, use the test virtual-template subinterface command in privileged EXEC mode.

test virtual-template template subinterface

Syntax Description

template

The identifying string of the virtual template to be tested.

Defaults

No default behavior or values.

Command Modes

Privileged EXEC

Command History

Release	Modification
12.2(13)T	This command was introduced.
12.2(15)B	This command was integrated into Cisco IOS Release 12.2(15)B.
12.2(28)SB	This command was integrated into Cisco IOS Release 12.2(28)SB.

Usage Guidelines

This command tests the specified virtual template to determine if it can support the creation of virtual access subinterfaces. If the virtual template cannot support subinterfaces, this command lists the commands that are configured on the virtual template and that are incompatible with subinterfaces.

Examples

The following example tests virtual template 1 to determine if it can support subinterfaces. The output shows that the traffic-shape rate 50000 8000 8000 1000 command that is configured on virtual template 1 prevents the virtual template from being able to support subinterfaces.

Router# test virtual-template 1 subinterface

Subinterfaces cannot be created using Virtual-Template1

Interface specific commands:

traffic-shape rate 50000 8000 8000 1000

Related Commands

Command	Description
debug vtemplate subinterface	Displays debug messages relating to virtual access subinterfaces.
virtual-template subinterface	Enables the creation of virtual access subinterfaces.

virtual-template subinterface

To enable the creation of virtual access subinterfaces, use the virtual-template subinterface command in global configuration mode. To disable the creation of virtual access subinterfaces, use the no form of this command.

virtual-template subinterface

no virtual-template subinterface

Syntax Description

This command has no arguments or keywords.

Defaults

This command is enabled by default.

Command Modes

Global configuration

Command History

Release	Modification
12.2(13)T	This command was introduced.
12.2(15)B	The command was integrated into Cisco IOS Release 12.2(15)B.
12.2(28)SB	This command was integrated into Cisco IOS Release 12.2(28)SB.

Usage Guidelines

This command does not appear in running configurations. Only the no form of the command will appear in running configurations.

Examples

The following example disables the creation of virtual access subinterfaces:

no virtual-template subinterface

Related Commands

Command	Description
debug vtemplate subinterface	Displays debug messages relating to virtual access subinterfaces.
test virtual-template subinterface	Tests a virtual template to determine if it can support virtual access subinterfaces.

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

© 2002-2003, 2006 Cisco Systems, Inc. All rights reserved.