Using Multilink PPP over Dialer Interface Links

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

This module was first published on May 2, 2005, and last updated on May 2, 2005.

Finding Feature Information in This Module

Your Cisco IOS software release may not support all of the features documented in this module. For the latest feature information and caveats, see the release notes for your platform and software release. To reach links to specific feature documentation in this module and to see a list of the releases in which each feature is supported, use the "Feature Information for Using Multilink PPP over Dialer Interface Links" section.

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Contents

•Prerequisites for Using Multilink PPP over Dialer Interface Links

•Restrictions for Using Multilink PPP over Dialer Interface Links

•Information About Using Multilink PPP over Dialer Interface Links

•How to Configure Multilink PPP over Dialer Interface Links

•Configuration Examples for Using Multilink PPP over Dialer Interface Links

•Where to Go Next

•Additional References

•Feature Information for Using Multilink PPP over Dialer Interface Links

Prerequisites for Using Multilink PPP over Dialer Interface Links

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

•Multilink uses first-in first out (FIFO) queuing for queuing and interleaving packets. Other queuing mechanisms such as low latency queuing (LLQ), weighted fair queuing (WFQ), and class-based weighted fair queuing (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 Dialer Interface Links

•Route/switch processing (RSP) is not recommended when using Multilink PPP over dialer interface links.

Information About Using Multilink PPP over Dialer Interface Links

•Dialer Profiles

•MQC and Multilink PPP over Dialer Interface Links

Dialer Profiles

The dialer profiles implementation of dial-on-demand routing (DDR) is based on a separation between logical and physical interface configuration. Dialer profiles also allow the logical and physical configurations to be bound together dynamically on a per-call basis.

Dialer profiles are advantageous in the following situations:

•When you want to share an interface (ISDN, asynchronous, or synchronous serial) to place or receive calls.

•When you want to change any configuration on a per-user basis.

•When you want to maximize ISDN channel usage using the Dynamic Multiple Encapsulations feature to configure various encapsulation types and per-user configurations on the same ISDN B channel at different times according to the type of call.

•When you want to bridge to many destinations, and for avoiding split horizon problems.

Most routed protocols are supported; however, International Organization for Standardization Connectionless Network Service (ISO CLNS) is not supported.

If you decide to configure dialer profiles, you must disable validation of source addresses for the routed protocols you support.

MQC and Multilink PPP over Dialer Interface Links

Before using Multilink PPP over dialer interface links, a traffic policy (also known as 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).

The MQC is a CLI structure that allows users to create traffic policies (policy maps) and attach these policy maps to interfaces. A policy map contains a traffic class and one or more QoS features. A traffic class is used to classify traffic. The QoS features in the traffic policy determine how to treat the classified traffic.

How to Configure Multilink PPP over Dialer Interface Links

Configuring Multilink PPP over Dialer Interface Links

Prerequisites

Before proceeding with this task, you must create a policy map. The policy map contains the configuration parameters used to apply the specific quality of service feature to the network traffic. To create a policy map, use the MQC. See the "MQC and Multilink PPP over Dialer Interface Links" section.

SUMMARY STEPS

1. enable

2. configure terminal

3. interface dialer dialer-rotary-group-number

4. ip address ip-address mask [secondary]

5. ip unnumbered type number

6. encapsulation encapsulation-type

7. dialer pool number

8. dialer in-band [no-parity | odd-parity]

9. service-policy output policy-map-name

10. service-policy input policy-map-name

11. ppp authentication {protocol1 [protocol2...]} [if-needed] [list-name | default] [callin] [one-time] [optional]

12. ppp chap hostname hostname

13. ppp chap password secret

14. ppp multilink [bap]

15. ppp multilink fragment delay milliseconds [microseconds]

16. ppp multilink interleave

17. 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 dialer dialer-rotary-group-number

Example:

Router(config)# interface dialer 1

Defines a dialer rotary group and enters interface configuration mode.

•Enter the dialer rotary group 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  

ip unnumbered type number
Example:

Router(config-if)# ip unnumbered ethernet 0

(Optional) Enables IP processing on a serial interface without assigning an explicit IP address to the interface.

•Enter the type and number of another interface on which the router has an assigned IP address. It cannot be another unnumbered interface.

Step 6  

encapsulation encapsulation-type
Example:

Router(config-if)# encapsulation ppp

Sets the encapsulation method used by the interface.

•Enter the encapsulation method. For this feature, enter ppp.

Step 7  

dialer pool number
Example:

Router(config-if)# dialer pool 3

(Optional) Specifies which dialing pool to use to connect to a specific destination subnetwork.

•Enter the dialing pool number.

Step 8  

dialer in-band [no-parity | odd-parity]
Example:

Router(config-if)# dialer in-band

(Optional) Specifies that dial-on-demand routing (DDR) is to be supported.

Step 9  

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 10  

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 11 

ppp authentication {protocol1 [protocol2...]} [if-needed] [list-name | default] [callin] [one-time] [optional]

Example:

Router(config-if)# ppp authentication chap

Enables at least one Point-to-Point Protocol (PPP) authentication protocol and specifies the order in which the protocols are selected on the interface.

•Enter the PPP authentication protocol to be used.

Step 12 

ppp chap hostname hostname

Example:

Router(config-if)# ppp chap hostname ISPCorp

Creates a pool of dialup routers that all appear to be the same host when authenticating with Challenge Handshake Authentication Protocol (CHAP).

•Enter the name sent in the CHAP challenge.

Step 13 

ppp chap password secret

Example:

Router(config-if)# ppp chap password 7

Enables a router calling a collection of routers that do not support this command (such as routers running older Cisco IOS software images) to configure a CHAP secret password to use in response to challenges from an unknown peer.

•Enter the secret password used to compute the response value for any CHAP challenge from an unknown peer.

Step 14 

ppp multilink [bap]

Example:

Router(config-if)# ppp multilink

Enables multilink on an interface.

Step 15 

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 16 

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 17 

end

Example:

Router(config-if)# end

(Optional) Exits interface configuration mode.

Associating the Dialer Interface with a BRI

SUMMARY STEPS

1. enable

2. configure terminal

3. interface bri number

4. dialer pool-member number [priority priority] [min-link minimum] [max-link maximum]

5. dialer rotary-group interface-number

6. ppp multilink [bap]

7. 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 bri number

Example:

Router(config)# interface bri 1

Configures a BRI interface and enters interface configuration mode.

•Enter port, connector, or interface card number.

Step 4 

dialer pool-member number [priority priority] [min-link minimum] [max-link maximum]

Example:

Router(config-if)# dialer pool-member 3

(Optional) Configures a physical interface to be a member of a dialer profile dialing pool.

•Enter the dialer profile dialing pool number.

Step 5 

dialer rotary-group interface-number

Example:

Router(config-if)# dialer rotary-group 1

(Optional) Includes a specified interface in a dialer rotary group.

•Enter the number of the dialer interface (defined in Step 4) in whose rotary group this interface is to be included.

Step 6 

ppp multilink [bap]

Example:

Router(config-if)# ppp multilink

Enables Multilink on an interface.

Step 7 

end

Example:

Router(config-if)# end

(Optional) Exits interface configuration mode.

Verifying the Multilink PPP over Dialer Interface Link Configuration

SUMMARY STEPS

1. enable

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

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

4. 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 interfaces [type number] [first] [last] 
[accounting]
Example:

Router# show interfaces

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

Step 3  

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

Router# show ppp multilink

(Optional) Displays bundle information for the multilink bundles.

Step 4 

exit

Example:

Router# exit

(Optional) Exits privileged EXEC mode.

Configuration Examples for Using Multilink PPP over Dialer Interface Links

Example: Configuring Multilink PPP over Dialer Interface Links

The following is an example of configuring Multilink PPP over a dialer interface link:

Router> enable

Router# configure terminal

Router(config)# interface dialer 1 

Router(config-if)# ip address 10.10.100.1 255.255.255.0

Router(config-if)# encapsulation ppp

Router(config-if)# dialer pool 3

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

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

Router(config-if)# ppp authentication chap

Router(config-if)# ppp chap hostname ISPCorp

Router(config-if)# ppp chap password 7

Router(config-if)# ppp multilink

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

Router(config-if)# ppp multilink interleave

Router(config-if)# end

Example: Associating the Dialer Interface with a BRI

The following is an example of associating the dialer interface with a BRI:

Router> enable

Router# configure terminal

Router(config)# interface bri 1

Router(config-if)# dialer pool-member 3

Router(config-if)# ppp multilink

Router(config-if)# end

Example: Verifying the Multilink PPP over Dialer Interface Link Configuration

You can verify the Multilink PPP over dialer interface link configuration by using one or more of the following show commands:

•show interfaces

•show ppp multilink

The following section provides sample output of the show ppp multilink command only. For sample output of the other commands, see the appropriate Cisco IOS Release 12.3 T command reference publication.

show ppp multilink Command Output Example

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 one member link. 

Router# show ppp multilink


Dialer2, bundle name is 7206-2

  Username is 7206-2

  Endpoint discriminator is 7206-2

  Bundle up for 00:00:10, 1/255 load

  Receive buffer limit 12000 bytes, frag timeout 1500 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 (max not set, min not set)

    BR2/0:1, since 00:00:09

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 ATM links, see the "Using Multilink PPP over ATM 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 Multilink PPP over dialer interface 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

Dialer profiles and DDR

"Preparing to Configure DDR" module

Multilink PPP configuration information

"Configuring Media-Independent PPP and Multilink PPP" 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 ATM links (including ATM interfaces and ATM PVCs)

"Using Multilink PPP over ATM 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 Dialer Interface Links

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 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 Dialer Interface Links

Feature Name
Software Releases
Feature Configuration Information

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 dialer interface links.

The following sections provide information about this feature:

•Information About Using Multilink PPP over Dialer Interface Links

•How to Configure Multilink PPP over Dialer Interface Links

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 dialer interface links.

The following sections provide information about this feature:

•Information About Using Multilink PPP over Dialer Interface Links

•How to Configure Multilink PPP over Dialer Interface Links


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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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