Using Multilink PPP over ATM Links

First Published: May 2, 2005
Last Updated: March 21, 2011

This module contains conceptual information and configuration tasks for using Multilink PPP over ATM links. Multilink PPP is a method that is used to reduce latency and jitter for real-time traffic.

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 Using Multilink PPP over ATM Links" section.

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

•Prerequisites for Using Multilink PPP over ATM Links

•Restrictions for Using Multilink PPP over ATM Links

•Information About Using Multilink PPP over ATM Links

•How to Configure Multilink PPP over ATM Links

•Configuration Examples for Using Multilink PPP over ATM Links

•Where to Go Next

•Additional References

•Feature Information for Using Multilink PPP over ATM Links

Prerequisites for Using Multilink PPP over ATM Links

•Be familiar with the concepts in the "Reducing Latency and Jitter for Real-Time Traffic Using Multilink PPP" module.

•Multilink PPP uses first-in first-out (FIFO) queueing for queueing and interleaving packets. Other queueing mechanisms such as low latency queueing (LLQ), weighted fair queueing (WFQ), and class-based weighted fair queueing (CBWFQ) can be used. If you want to use one of these alternative mechanisms, enable it before configuring Multilink.

Restrictions for Using Multilink PPP over ATM Links

•Only Voice over IP (VoIP) is supported; Voice over ATM is not supported.

•Multilink PPP over ATM must use the following ATM network modules:

–Multiport T1/E1 ATM Network Module with Inverse Multiplexing over ATM

–ATM OC-3 Network Module

–Enhanced ATM Port Adapter

Information About Using Multilink PPP over ATM Links

•MQC and Multilink PPP over ATM Links

•Virtual Template Interfaces

•Multilink Group Interfaces

MQC and Multilink PPP over ATM Links

Before using Multilink PPP over ATM links, a policy map must be created. (See the "Prerequisites" section.) Policy maps are created using the Modular Quality of Service (QoS) Command-Line Interface (CLI) (MQC).

Virtual Template Interfaces

A virtual template interface is a logical interface that is configured with generic configuration information for a specific purpose or a configuration common to specific users, plus router-dependent information. The template takes the form of a list of Cisco IOS interface commands that are applied to virtual access interfaces, as needed.

Multilink Group Interfaces

A multilink group interface is a collection of interfaces that are bundled together in the multilink PPP configuration. With a multilink group interface, you can bundle interfaces into logical multilink groups.

How to Configure Multilink PPP over ATM Links

Note While the first two procedures are listed as optional, you must choose one or the other according to the Cisco router that you are using in your network.

•Configuring Multilink PPP over ATM Links on a Virtual Template Interface (optional; applies only if you are using the Cisco 7500 series router or the Cisco 7600 series router)

or

•Configuring Multilink PPP over ATM Links on a Multilink Group Interface (optional)

•Associating the Virtual Template Interface with an ATM PVC (required)

•Verifying the Multilink PPP over ATM Links Configuration (optional)

Configuring Multilink PPP over ATM Links on a Virtual Template Interface

Note These steps apply if you are using the Cisco 7500 series router or the Cisco 7600 series router only. If you are using another series of Cisco router, do not complete these steps. Instead, advance to the "Configuring Multilink PPP over ATM Links on a Multilink Group Interface" section.

Prerequisites

Before proceeding with this task, you must create a policy map. The policy map contains the configuration parameters used to apply a specific QoS feature, such as distributed LLQ (dLLQ), to the network traffic.

SUMMARY STEPS

1. enable

2. configure terminal

3. interface virtual-template number

4. bandwidth kbps

5. ip address ip-address mask [secondary]

6. service-policy output policy-map-name

7. service-policy input policy-map-name

8. ppp multilink

9. ppp multilink fragment delay milliseconds [microseconds]

10. ppp multilink interleave

11. end

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 virtual-template number

Example:

Router(config)# interface virtual-template 4

Creates a virtual template and enters interface configuration mode.

•Enter the virtual template number.

Step 4 

bandwidth kbps

Example:

Router(config-if)# bandwidth 32

Sets the bandwidth value for an interface.

•Enter the bandwidth value in kilobits per second.

Step 5  

ip address ip-address mask [secondary]
Example: 
Router(config-if)# ip address 10.10.100.1 
255.255.255.0

Sets a primary IP address for an interface. This command can also set the optional secondary IP address for an interface.

•Enter the primary IP address (and, optionally, the secondary IP address).

Step 6  

service-policy output policy-map-name
Example:

Router(config-if)# service-policy output policy1

Attaches the previously created QoS traffic policy (policy map). The policy map evaluates and applies QoS features for traffic leaving the interface.

•Enter the policy map name.

Step 7  

service-policy input policy-map-name
Example:

Router(config-if)# service-policy input policy1

Attaches the previously created QoS traffic policy (policy map). The policy map evaluates and applies QoS features for traffic entering the interface.

•Enter the policy map name.

Step 8 

ppp multilink

Example:

Router(config-if)# ppp multilink

Enables Multilink PPP (MLP) on the interface.

Step 9 

ppp multilink fragment delay milliseconds [microseconds]

Example:

Router(config-if)# ppp multilink fragment delay 20

Specifies a maximum size in units of time for packet fragments on an MLP bundle.

•Enter the maximum amount of time, in milliseconds.

Note The fragment delay can be calculated using the following formula:

fragment delay = (fragment size * 8)/bandwidth

Step 10 

ppp multilink interleave

Example:

Router(config-if)# ppp multilink interleave

Enables interleaving of packets among the fragments of larger packets on a multilink bundle.

Step 11 

end

Example:

Router(config-if)# end

(Optional) Exits interface configuration mode and returns to privileged EXEC mode.

Configuring Multilink PPP over ATM Links on a Multilink Group Interface

Note If you are using the Cisco 7500 series router or the Cisco 7600 series router, do not complete these steps. Instead, complete the steps in "Configuring Multilink PPP over ATM Links on a Virtual Template Interface" section.

Prerequisites

Before proceeding with this task, you must create a policy map. The policy map contains the configuration parameters used to apply a specific QoS feature, such as distributed LLQ (dLLQ), to the network traffic.

SUMMARY STEPS

1. enable

2. configure terminal

3. interface multilink multilink-bundle-number

4. ip address ip-address mask [secondary]

5. service-policy output policy-map-name

6. service-policy input policy-map-name

7. ppp multilink fragment delay milliseconds [microseconds]

8. ppp multilink interleave

9. ppp multilink multiclass

10. end

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 multilink multilink-bundle-number

Example:

Router(config)# interface multilink 1

Creates a multilink bundle and enters interface configuration mode.

•Enter the multilink bundle number.

Step 4  

ip address ip-address mask [secondary]
Example: 
Router(config-if)# ip address 10.10.100.1 
255.255.255.0

Sets a primary IP address for an interface. This command can also set the optional secondary IP address for an interface.

•Enter the primary IP address (and, optionally, the secondary IP address).

Step 5  

service-policy output policy-map-name
Example:

Router(config-if)# service-policy output policy1

Attaches the previously created QoS traffic policy (policy map). See the "Prerequisites" section. The policy map evaluates and applies QoS features for traffic leaving the interface.

•Enter the policy map name.

Step 6  

service-policy input policy-map-name
Example:

Router(config-if)# service-policy input policy1

Attaches the previously created QoS traffic policy (policy map). See the "Prerequisites" section. The policy map evaluates and applies QoS features for traffic entering the interface.

•Enter the policy map name.

Step 7 

ppp multilink fragment delay milliseconds [microseconds]

Example:

Router(config-if)# ppp multilink fragment delay 20

Specifies a maximum size in units of time for packet fragments on a Multilink PPP (MLP) bundle.

•Enter the maximum amount of time, in milliseconds.

Step 8 

ppp multilink interleave

Example:

Router(config-if)# ppp multilink interleave

Enables interleaving of packets among the fragments of larger packets on a multilink bundle.

Step 9 

ppp multilink multiclass

Example:

Router(config-if)# ppp multilink multiclass

(Optional) Enables Multiclass Multilink PPP (MCMP) on an interface.

Note Use this command only if there are multiple links in the multilink bundle.

Step 10 

end

Example:

Router(config-if)# end

(Optional) Exits interface configuration mode and returns to privileged EXEC mode.

What to Do Next

After configuring Multilink PPP over ATM links on a multilink group interface, the next step is to associate the virtual template interface with the multilink group by completing the steps in the following section.

If you are using a Cisco 7500 series router or a Cisco 7600 series router, advance to the "Associating the Virtual Template Interface with an ATM PVC" section to continue.

Associating the Virtual Template Interface with the Multilink Group

SUMMARY STEPS

1. enable

2. configure terminal

3. interface virtual-template number

4. no ip address [ip-address mask [secondary]]

5. ppp multilink group group-number

6. end

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 virtual-template number

Example:

Router(config)# interface virtual-template 2

Creates a virtual template interface that can be configured and applied dynamically in creating virtual access interfaces, and enters interface configuration mode.

•Enter the number used to identify the virtual template interface.

Step 4 

no ip address [ip-address mask [secondary]]

Example:

Router(config-if)# no ip address

Removes an IP address or disables IP processing.

Step 5 

ppp multilink group group-number

Example:

Router(config-if)# ppp multilink group 1

Restricts a physical link to joining only a designated multilink group interface.

•Enter the multilink group number.

Step 6 

end

Example:

Router(config-if)# end

(Optional) Exits interface configuration mode and returns to privileged EXEC mode.

Associating the Virtual Template Interface with an ATM PVC

SUMMARY STEPS

1. enable

2. configure terminal

3. interface type number [name-tag]

4. pvc [name] vpi/vci [ces | ilmi | qsaal | smds | l2transport]

5. abr output-pcr output-mcr

6. vbr-nrt output-pcr output-scr output-mbs [input-pcr] [input-scr] [input-mbs]

7. protocol ppp virtual-template number

8. end

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 type number [name-tag]

Example:

Router(config)# interface atm2/0/0

Configures an interface type and enters interface configuration mode.

•Enter the interface type and number.

Step 4 

pvc [name] vpi/vci [ces | ilmi | qsaal | smds | l2transport]

Example:

Router(config-if)# pvc cisco 0/16

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

•Enter the ATM PVC name, the network virtual path identifier, and the network virtual channel identifier.

Step 5 

abr output-pcr output-mcr

Example:

Router(config-if-atm-vc)# abr 100 80

(Optional) Selects available bit rate (ABR) QoS and configures the output peak cell rate (PCR) and output minimum guaranteed cell rate (MCR) for an ATM PVC.

•Enter the output PCR and the output MCR.

Step 6 

vbr-nrt output-pcr output-scr output-mbs [input-pcr] [input-scr] [input-mbs]

Example:

Router(config-if-atm-vc)# vbr-nrt 1100 1100 100

(Optional) Configures the variable bit rate-nonreal time (VBR-NRT) quality of service (QoS) and specifies the output peak cell rate (PCR), the output sustainable cell rate (SCR), and the output maximum burst cell size (MBS) for an ATM PVC, PVC range, switched virtual circuit (SVC), VC class, or VC bundle member.

•Enter the output PCR, SCR, and MBS.

Step 7 

protocol ppp virtual-template number

Example:

Router(config-if-atm-vc)# protocol ppp virtual-template 2

Specifies that PPP is established over the ATM PVC using the configuration from the specified virtual template.

•Enter the virtual-template number.

Step 8 

end

Example:

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

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

Verifying the Multilink PPP over ATM Links Configuration

SUMMARY STEPS

1. enable

2. show atm pvc [vpi/vci | name | interface atm interface-number [.subinterface-number multipoint]] [ppp]

3. show interfaces [type number] [first] [last] [accounting]

4. show ppp multilink [active | inactive | interface bundle-interface | [username name] [endpoint endpoint]]

5. show policy-map interface interface-name [vc [vpi/] vci] [dlci dlci] [input | output]

6. 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 atm pvc [vpi/vci | name | interface atm 
interface-number [.subinterface-number 
multipoint]] [ppp]
Example:

Router# show atm pvc

(Optional) Displays all ATM PVCs and traffic information.

Step 3  

show interfaces [type number] [first] [last] 
[accounting]
Example:

Router# show interfaces

(Optional) Displays statistics for all interfaces that are configured on the router or access server.

Step 4  

show ppp multilink [active | inactive | 
interface bundle-interface | [username name] 
[endpoint endpoint]]
Example:

Router# show ppp multilink

(Optional) Displays bundle information for multilink bundles.

Step 5  

show policy-map interface interface-name [vc 
[vpi/] vci] [dlci dlci] [input | output]
Example:

Router# show policy-map interface serial0/0

(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.

Step 6 

exit

Example:

Router# exit

(Optional) Exits privileged EXEC mode.

Configuration Examples for Using Multilink PPP over ATM Links

•Example: Configuring Multilink PPP over ATM Links on a Virtual Template Interface

•Example: Configuring Multilink PPP over ATM Links on a Multilink Group Interface

•Example: Associating the Virtual Template Interface with the Multilink Group

•Example: Associating the Virtual Template Interface with an ATM PVC

•Example: Verifying the Multilink PPP over ATM Links Configuration

Example: Configuring Multilink PPP over ATM Links on a Virtual Template Interface

The following is an example of configuring Multilink PPP over ATM links on a virtual template interface:

Router> enable

Router# configure terminal

Router(config)# interface virtual-template 4

Router(config-if)# bandwidth 32 

Router(config-if)# ip address 10.10.100.1 255.255.255.0

Router(config-if)# service-policy output policy1

Router(config-if)# service-policy input policy1

Router(config-if)# ppp multilink

Router(config-if)# ppp multilink fragment delay 20

Router(config-if)# ppp multilink interleave

Router(config-if)# end

Example: Configuring Multilink PPP over ATM Links on a Multilink Group Interface

The following is an example of configuring Multilink PPP over ATM links on a multilink group interface:

Router> enable

Router# configure terminal

Router(config)# interface multilink 1 

Router(config-if)# ip address 10.10.100.1 255.255.255.0

Router(config-if)# service-policy output policy1

Router(config-if)# service-policy input policy1

Router(config-if)# ppp multilink fragment delay 20

Router(config-if)# ppp multilink interleave

Router(config-if)# ppp multilink multiclass

Router(config-if)# end

Example: Associating the Virtual Template Interface with the Multilink Group

The following is an example of associating the virtual template interface with the multilink group:

Router> enable

Router# configure terminal

Router(config)# interface virtual-template 2

Router(config-if)# no ip address

Router(config-if)# ppp multilink group 1

Router(config-if)# end

Example: Associating the Virtual Template Interface with an ATM PVC

The following is an example of associating the virtual template interface with an ATM PVC:

Router> enable

Router# configure terminal

Router(config)# interface atm2/0/0

Router(config-if)# pvc cisco 0/16

Router(config-if-atm-vc)# abr 100 80

Router(config-if-atm-vc)# protocol ppp virtual-template 2

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

Example: Verifying the Multilink PPP over ATM Links Configuration

The following is an example of the show ppp multilink command output. In this example, one multilink bundle called 7206-2 is on the system. This bundle has two member links: one active link and one inactive link. 


Router# show ppp multilink


Multilink1, bundle name is 7206-2

  Endpoint discriminator is 7206-2

  Bundle up for 00:00:24, 1/255 load

  Receive buffer limit 12000 bytes, frag timeout 1000 ms

    0/0 fragments/bytes in reassembly list

    0 lost fragments, 0 reordered

    0/0 discarded fragments/bytes, 0 lost received

    0x0 received sequence, 0x0 sent sequence

  Member links: 1 active, 1 inactive (max not set, min not set)

    Vi3, since 00:00:24

    PPPoATM link, ATM PVC 2/101 on ATM2/0/0

    Packets in ATM PVC Holdq: 0 , Particles in ATM PVC Tx Ring: 1

    Vt1 (inactive)

Where to Go Next

To use Multilink PPP over Frame Relay, see the "Using Multilink PPP over Frame Relay" module.

To use Multilink PPP over dialer interface links, see the "Using Multilink PPP over Dialer Interface Links" module.

To use Multilink PPP over serial interface links, see the "Using Multilink PPP over Serial Interface Links" module.

Additional References

The following sections provide references related to using Multilink PPP over ATM links.

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, WFQ, CBWFQ, PQ, CQ, FIFO, and other queueing mechanisms

"Configuring Weighted Fair Queueing" module

MQC

"Applying QoS Features Using the MQC" module

Multilink PPP configurations

"Configuring Media-Independent PPP and Multilink PPP" module

Virtual template interfaces

"Configuring Virtual Template Interfaces" module

Multilink PPP overview module

"Reducing Latency and Jitter for Real-Time Traffic Using Multilink PPP" module

Multilink PPP over Frame Relay

"Using Multilink PPP over Frame Relay" module

Multilink PPP over dialer interface links

"Using Multilink PPP over Dialer Interface Links" module

Multilink PPP over serial interface links

"Using Multilink PPP over Serial Interface Links" module


Standards

Standard
Title

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

—


MIBs

MIB
MIBs Link

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

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

RFC 1990

The PPP Multilink Protocol (MP)

RFC 2686

Multiclass Extension to Multilink PPP (MCML)


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 Using Multilink PPP over ATM Links

Table 1 lists the features in this module and provides links to specific configuration information.

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 Using Multilink PPP over ATM Links 

Feature Name
Releases
Feature Information

Distributed Link Fragmentation and Interleaving for Frame Relay and ATM Interfaces on Cisco 7500 Series Routers

12.2(4)T

The Distributed Link Fragmentation and Interleaving (dLFI) for Frame Relay and ATM Interfaces on Cisco 7500 Series Routers feature extends link fragmentation and interleaving functionality to VIP-enabled Cisco 7500 series routers.

This feature was extensively rewritten from the perspective of using Multilink PPP for link fragmentation and interleaving over ATM interface links.

The following sections provide information about this feature:

•Information About Using Multilink PPP over ATM Links

•How to Configure Multilink PPP over ATM Links

Distributed Link Fragmentation and Interleaving over Leased Lines

12.2(8)T

The Distributed Link Fragmentation and Interleaving over Leased Lines feature extends distributed link fragmentation and interleaving functionality to leased lines.

This feature was extensively rewritten from the perspective of using Multilink PPP for link fragmentation and interleaving over ATM interface links.

The following sections provide information about this feature:

•Information About Using Multilink PPP over ATM Links

•How to Configure Multilink PPP over ATM Links

MLP LFI over ATM Configuration Scaling

12.2(25)S
12.2(27)SBA
15.0(1)M

The MLP LFI over ATM Configuration Scaling feature supports the transport of real-time (voice) and non-real-time (data) traffic on lower-speed Frame Relay and ATM permanent virtual circuits (PVCs) without causing excessive delay of real-time traffic.

The following sections provide information about this feature:

•Information About Using Multilink PPP over ATM Links

•How to Configure Multilink PPP over ATM Links

The following commands were introduced or modified: ppp multilink group


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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.

© 2011 Cisco Systems, Inc. All rights reserved.