Cisco IOS Quality of Service Solutions Configuration Guide, Release 12.4 - Using Multilink PPP over Serial Interface Links [Cisco IOS Software Releases 12.4 Mainline]

Table Of Contents

Using Multilink PPP over Serial Interface Links

Finding Feature Information in This Module

Contents

Prerequisites for Using Multilink PPP over Serial Interface Links

Restrictions for Using Multilink PPP over Serial Interface Links

Information About Using Multilink PPP over Serial Interface Links

MQC and Multilink PPP over Serial Interface Links

Multilink Group Interfaces

How to Configure Multilink PPP over Serial Interface Links

Configuring Multilink PPP over Serial Interface Links on a Multilink Group Interface

Prerequisites

Associating the Serial Interface with the Multilink Group

Verifying the Multilink PPP over Serial Interface Link Configuration

Configuration Examples for Using Multilink PPP over Serial Interface Links

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

Associating the Serial Interface with the Multilink Group: Example

Verifying the Multilink PPP over Serial Interface Link Configuration: Example

Where to Go Next

Additional References

Related Documents

Standards

MIBs

RFCs

Technical Assistance

Glossary

Feature Information for Using Multilink PPP over Serial Interface Links

Using Multilink PPP over Serial Interface Links

First Published: May 2, 2005

Last Updated: July 18, 2008

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

Finding Feature Information in This Module

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 Serial Interface 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 Serial Interface Links

•Restrictions for Using Multilink PPP over Serial Interface Links

•Information About Using Multilink PPP over Serial Interface Links

•How to Configure Multilink PPP over Serial Interface Links

•Configuration Examples for Using Multilink PPP over Serial Interface Links

•Where to Go Next

•Additional References

•Glossary

•Feature Information for Using Multilink PPP over Serial Interface Links

Prerequisites for Using Multilink PPP over Serial Interface Links

Knowledge

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

Enable Queueing Mechanism

•Multilink uses first-in first out (FIFO) queuing 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 Serial Interface Links

Number of Links per Multilink Bundle

If a multilink bundle has one link or packet order is not important for interleaved packets, use Link Fragmentation and Interleaving (LFI) without multiclass. Use LFI with multiclass if a multilink bundle has multiple links.

VoIP Support

Only Voice over IP (VoIP) is supported.

Queueing Mechanisms Not Supported

Many of the legacy queueing mechanisms are not supported by multilink. These mechanisms include:

•Fair queueing on a virtual template interface

•Weighted random early detection (WRED) on a virtual template interface

•Custom queueing

•Priority queueing

Note Fair queueing, WRED, and priority queueing can be configured in a traffic policy using the Modular Quality of Service (QoS) Command-Line Interface (CLI) (MQC).

Information About Using Multilink PPP over Serial Interface Links

To use Multilink PPP over serial interface links, you should understand the following concept:

•MQC and Multilink PPP over Serial Interface Links

•Multilink Group Interfaces

MQC and Multilink PPP over Serial Interface Links

Before using Multilink PPP over serial 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 polices (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.

For more information about MQC, see the "Applying QoS Features Using the MQC" module.

Multilink Group Interfaces

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

For more information about multilink group interfaces and multilink groups, see the "Configuring Media-Independent PPP and Multilink PPP" module.

How to Configure Multilink PPP over Serial Interface Links

This section contains the following procedures:

•Configuring Multilink PPP over Serial Interface Links on a Multilink Group Interface (required)

•Associating the Serial Interface with the Multilink Group (required)

•Verifying the Multilink PPP over Serial Interface Link Configuration (optional)

Configuring Multilink PPP over Serial Interface Links on a Multilink Group Interface

To configure Multilink PPP over serial interface links on a multilink group interface, complete the following steps.

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 Serial Interface Links" section.

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.
Associating the Serial Interface with the Multilink Group

To associate the serial interface with the multilink group, complete the following steps.

SUMMARY STEPS

1. enable

2. configure terminal

3. interface serial slot/port:timeslot

4. no fair-queue

5. encapsulation ppp

6. ppp multilink

7. ppp multilink group group-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 serial slot/port:timeslot
Example:

Router# interface serial 4/1:23
Specifies a serial interface created on a channelized E1 or channelized T1 controller (for ISDN PRI, channel-associated signaling, or robbed-bit signaling), and enters interface configuration mode.

•Enter the slot number and port number where the channelized E1 or T1 controller is located.
Step 4

no fair-queue
Example:

Router(config-if)# no fair-queue

Disables WFQ (or DWFQ for VIP-enabled routers).

Step 5

encapsulation ppp
Example:

Router(config-if)# encapsulation ppp

Sets the serial interface encapsulation method used by the interface.

Step 6

ppp multilink
Example:

Router(config-if)# ppp multilink

Enables Multilink on an interface.

Step 7

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 8

end
Example:

Router(config-if)# end

(Optional) Exits interface configuration mode.
Verifying the Multilink PPP over Serial Interface Link Configuration

To verify the Multilink PPP over serial interface link configuration, complete the following steps.

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

5. 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 mutlilink bundles.
Step 4
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 permanent virtual circuit (PVC) on the interface.
Step 5

exit
Example:

Router# exit

(Optional) Exits privileged EXEC mode.
Configuration Examples for Using Multilink PPP over Serial Interface Links

This section contains the following examples:

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

•Associating the Serial Interface with the Multilink Group: Example

•Verifying the Multilink PPP over Serial Interface Link Configuration: Example

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

The following is an example of configuring Multilink PPP over serial interface 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
Associating the Serial Interface with the Multilink Group: Example

The following is an example of associating the serial interface serial4/1 with the multilink group:

Router> enable
Router# configure terminal
Router(config)# interface serial 4/1:23
Router(config-if)# no fair-queue
Router(config-if)# encapsulation ppp
Router(config-if)# ppp multilink
Router(config-if)# ppp multilink group 1
Router(config-if)# end
Verifying the Multilink PPP over Serial Interface Link Configuration: Example

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

•show interfaces

•show ppp multilink

•show policy-map interface

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 two member links: one active link and one inactive link.
Router# show ppp multilink
Multilink2, bundle name is 7206-2
  Endpoint discriminator is 7206-2
  Bundle up for 00:00:09, 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, 0x3 sent sequence
  Member links:1 active, 1 inactive (max not set, min not set)
    Se3/2, since 00:00:10, 240 weight, 232 frag size
    Se3/3 (inactive)
Where to Go Next

To use Multilink PPP over ATM links, see the "Using Multilink PPP over ATM Links" module.

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.

Additional References

The following sections provide references related to Multilink PPP over serial 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

Multilink PPP configurations

"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 ATM links (including ATM interfaces and ATM PVCs)

"Using Multilink PPP over ATM Links" 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

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 website provides extensive online resources, including documentation and tools for troubleshooting and resolving technical issues with Cisco products and technologies.

To receive security and technical information about your products, you can subscribe to various services, such as the Product Alert Tool (accessed from Field Notices), the Cisco Technical Services Newsletter, and Really Simple Syndication (RSS) Feeds.

Access to most tools on the Cisco Support website requires a Cisco.com user ID and password.

http://www.cisco.com/techsupport

Glossary

PVC—permanent virtual circuit (or connection). Virtual circuit that is permanently established. PVCs save bandwidth associated with circuit establishment and teardown in situations where certain virtual circuits must exist all the time. In ATM terminology, called a permanent virtual connection.

virtual template interface—A logical interface configured with generic configuration information for a specific purpose or 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.

Feature Information for Using Multilink PPP over Serial Interface Links

Table 1 lists the release history for this feature.

Not all commands may be available in your Cisco IOS software release. For details on when support for specific commands was introduced, see the command reference documents.

For information on a feature in this technology that is not documented here, see the "Reducing Latency and Jitter Using Multilink PPP Roadmap" module.

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 Serial 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 serial interface links.

The following sections provide information about this feature:

•Information About Using Multilink PPP over Serial Interface Links

•How to Configure Multilink PPP over Serial 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 serial interface links.

The following sections provide information about this feature:

•Information About Using Multilink PPP over Serial Interface Links

•How to Configure Multilink PPP over Serial Interface Links

CCDE, CCENT, Cisco Eos, Cisco Lumin, Cisco Nexus, Cisco StadiumVision, Cisco TelePresence, Cisco WebEx, the Cisco logo, DCE, and Welcome to the Human Network are trademarks; Changing the Way We Work, Live, Play, and Learn and Cisco Store are service marks; and Access Registrar, Aironet, AsyncOS, Bringing the Meeting To You, Catalyst, CCDA, CCDP, CCIE, CCIP, CCNA, CCNP, CCSP, CCVP, Cisco, the Cisco Certified Internetwork Expert logo, Cisco IOS, Cisco Press, Cisco Systems, Cisco Systems Capital, the Cisco Systems logo, Cisco Unity, Collaboration Without Limitation, EtherFast, EtherSwitch, Event Center, Fast Step, Follow Me Browsing, FormShare, GigaDrive, HomeLink, Internet Quotient, IOS, iPhone, iQuick Study, IronPort, the IronPort logo, LightStream, Linksys, MediaTone, MeetingPlace, MeetingPlace Chime Sound, MGX, Networkers, Networking Academy, Network Registrar, PCNow, PIX, PowerPanels, ProConnect, ScriptShare, SenderBase, SMARTnet, Spectrum Expert, StackWise, The Fastest Way to Increase Your Internet Quotient, TransPath, WebEx, and the WebEx logo are registered trademarks of Cisco Systems, Inc. and/or its affiliates in the United States and certain other countries.

All other trademarks mentioned in this document or website 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. (0809R)

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.

© 2005-2008 Cisco Systems, Inc. All rights reserved.