ATM Multilink PPP Support on Multiple VCs

The ATM Multilink PPP Support on Multiple VCs feature facilitates traffic load balancing on high-speed virtual circuits (VCs) using multilink PPP (MLP) over Frame Relay and ATM. It also facilitates traffic load balancing by using MLP to combine packet datagrams on high-speed VCs as a means of transporting both the voice and data traffic more efficiently.

Restrictions for ATM Multilink PPP Support

The ATM Multilink PPP Support on Multiple VCs feature does not support the following commands and functionality. The configuration accepts these commands, but the commands have no effect:

  • ppp interleave

  • ppp multilink fragment-delay

The ATM Multilink PPP Support on Multiple VCs feature does not support the link fragmentation and interleaving (LFI) functionality.

Information About ATM Multilink PPP Support

ATM Multilink PPP Support Overview

Load balancing operates at Layer 2 or Layer 3 (the network layer) of the Open System Interconnection (OSI) reference model. Layer 3 load balancing is independent of any link-layer technologies. The ATM Multilink Point-to-Point Protocol (PPP) Support on Multiple VCs feature implements load balancing at Layer 2 and depends on having MLP enabled at the link layer.

The ATM MLP functionality keeps track of packet sequencing, and this functionality buffers any packets that arrive early. With this ability, ATM MLP preserves packet order across the entire bundle.

In addition to MLP, low latency queueing (LLQ) and class-based weighted fair queueing (CBWFQ) are used to prioritize and differentiate the voice and data packets. LLQ and CBWFQ help to ensure that the voice and data traffic receive the proper quality of service (QoS) treatment (such as the correct priority queue assignment) when the voice and data traffic are transmitted.

For more information about LLQ and CBWFQ, see the Cisco IOS Quality of Service Solutions Configuration Guide.

Benefits of ATM Multilink PPP Support

Facilitates More Efficient Traffic Load Balancing

The ATM Multilink PPP Support on Multiple VCs feature supports the transport of real-time (voice) and other (data) traffic on Frame Relay and ATM VCs.

How to Configure ATM Multilink PPP Support

Defining the Service Policy Using the MQC

Perform this task to define the service policy using the MQC. The MQC allows you to create class maps and define service policies. Service policies are used to create classes and set match criteria for classifying traffic.

SUMMARY STEPS

  1. enable
  2. configure terminal
  3. class-map class-map-name [match-all | match-any ]
  4. match ip precedence ip-precedence-value [ip-precedence-value ip-precedence-value ip-precedence-value ]
  5. exit
  6. policy-map policy-name
  7. class-map class-map-name [match-all | match-any
  8. bandwidth {bandwidth-kbps | percent percent }
  9. 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

class-map class-map-name [match-all | match-any ]

Example:


Router(config)# class-map class1

Specifies the name of the class map to be created and enters class-map configuration mode. If match-all or match-any value is not specified, traffic must match all the match criteria to be classified as part of the class map.

Step 4

match ip precedence ip-precedence-value [ip-precedence-value ip-precedence-value ip-precedence-value ]

Example:


Router(config-cmap)# match ip precedence 3 2 4

Identifies IP precedence values as match criteria.

Step 5

exit

Example:


Router(config-cmap)# exit

Exits class-map configuration mode.

Step 6

policy-map policy-name

Example:


Router(config)# policy-map policy1

Specifies the name of the policy map to be created and enters policy-map configuration mode.

Step 7

class-map class-map-name [match-all | match-any

Example:


Router(config-pmp)# class class2

Classifies traffic based on the class map specified and enters policy-map class configuration mode.

Step 8

bandwidth {bandwidth-kbps | percent percent }

Example:


Router (config-pmap-c)# bandwidth 45

Specifies a minimum bandwidth guarantee to a traffic class in periods of congestion.

  • A minimum bandwidth guarantee can be specified in kbps or by a percentage of the overall available bandwidth.

Step 9

end

Example:


Router(config-pmp)# end

Exits class-map configuration mode.

Defining a Multilink MLP Bundle Interface

Perform this task to define a multilink MLP bundle interface. The purpose of a multilink bundle interface is to combine more than one permanent virtual circuit (PVC). All configurations for PPP over ATM links are placed into virtual templates, and the bundle parameters are placed into the multilink bundle.

SUMMARY STEPS

  1. enable
  2. configure terminal
  3. interface type number
  4. ip address ip-address mask [secondary ]
  5. load-interval seconds
  6. no cdp enable
  7. service-policy output policy-name
  8. ppp multilink
  9. ppp multilink fragment disable
  10. ppp multilink group group-number
  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 type number

Example:


Router(config)# interface multilink 34

Configures an interface type and enters interface configuration mode.

Step 4

ip address ip-address mask [secondary ]

Example:


Router(config-if)# ip address 209.165.201.1  255.255.255.0

Sets a primary or secondary IP address for an interface.

Step 5

load-interval seconds

Example:


Router(config-if)# load-interval 60

Changes the length of time for which data is used to compute load statistics.

Step 6

no cdp enable

Example:


Router(config-if)# no cdp enable

Disables Cisco Discovery Protocol (CDP) on an interface.

Step 7

service-policy output policy-name

Example:


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

Attaches the specified policy map to the output interface.

Step 8

ppp multilink

Example:


Router(config-if)# ppp multilink

Enables MLP on an interface.

Step 9

ppp multilink fragment disable

Example:


Router(config-if)# ppp multilink fragment disable

Disables packet fragmentation.

Step 10

ppp multilink group group-number

Example:


Router(config-if)# ppp multilink group 54

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

Step 11

end

Example:


Router(config-if)# end

Exits interface configuration mode.

Defining the Virtual Templates for Member Links

SUMMARY STEPS

  1. enable
  2. configure terminal
  3. interface type number
  4. no ip address
  5. load-interval seconds
  6. ppp multilink
  7. ppp multilink group group-number
  8. end

DETAILED STEPS

  Command or Action Purpose

Step 1

enable

Example:


Device> enable

Enables privileged EXEC mode.

  • Enter your password if prompted.

Step 2

configure terminal

Example:


Device# configure terminal

Enters global configuration mode.

Step 3

interface type number

Example:


Device(config)# interface multilink 34

Configures an interface type and enters interface configuration mode.

Step 4

no ip address

Example:


Device(config-if)# no ip address

Removes existing IP addresses or disables IP processing.

Step 5

load-interval seconds

Example:


Device(config-if)# load-interval 30

Changes the length of time for which data is used to compute load statistics.

Step 6

ppp multilink

Example:


Device(config-if)# ppp multilink

Enables MLP on the interface.

Step 7

ppp multilink group group-number

Example:


Device(config-if)# ppp multilink-group 44

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

Step 8

end

Example:


Device(config-if)#
 
end

Exits interface configuration mode.

Defining the PVCs and Bundling Member Links

SUMMARY STEPS

  1. enable
  2. configure terminal
  3. Do one of the following:
    • interface atm slot /0
    • interface atm slot / port
  4. no ip address
  5. load interval seconds
  6. atm ilmi-keepalive [seconds [retry [seconds ]]]
  7. pvc [name ] vpi/ vci
  8. vbr-nrt output-pcr output-scr [output-mbs ]
  9. tx-ring-limit ring-limit
  10. protocol ppp virtual-template number
  11. end

DETAILED STEPS

  Command or Action Purpose

Step 1

enable

Example:


Device> enable

Enables privileged EXEC mode.

  • Enter your password if prompted.

Step 2

configure terminal

Example:


Device# configure terminal

Enters global configuration mode.

Step 3

Do one of the following:

  • interface atm slot /0
  • interface atm slot / port

Example:


Device(config)# interface atm 2/0

Example:


or

Example:


Device(config)# interface atm 2/1

Specifies the ATM interface type and enters interface configuration mode.

Step 4

no ip address

Example:


Device(config-if)# no ip address

Removes an IP address or disables IP processing.

Step 5

load interval seconds

Example:


Device(config-if)# load interval 30

Changes the length of time for which data is used to compute load statistics.

Step 6

atm ilmi-keepalive [seconds [retry [seconds ]]]

Example:


Device(config-if)# atm ilmi-keepalive

Enables Interim Local Management Interface (ILMI) keepalives.

Step 7

pvc [name ] vpi/ vci

Example:


Device(config-if)# pvc pvc1 0/56

Creates an ATM PVC. Enters interface-ATM-VC configuration mode.

Step 8

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

Example:


Device(config-if-atm-vc)# vbr-nrt 45 4 45

Configures the variable bit rate (VBR)-non real time (NRT) QoS and specifies output peak cell rate, output sustainable cell rate, and output maximum burst cell size.

Step 9

tx-ring-limit ring-limit

Example:


Device(config-if-atm-vc)# tx-ring-limit 3

Limits the number of particles or packets that can be used on a transmission ring on an interface.

  • Use this command to tune the transmission ring to assign most of the packets to the Layer 3 queues.

Step 10

protocol ppp virtual-template number

Example:


Device(config-if-atm-vc)# protocol ppp virtual-template 34

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

Step 11

end

Example:


Device(config-if)# end

Exits interface configuration mode.

Verifying ATM Multilink PPP Support

Perform this task to display information about ATM Multilink PPP Support on Multiple VCs:

SUMMARY STEPS

  1. enable
  2. show atm pvc
  3. show frame-relay pvc [[interface interface ] [dlci ] [64-bit ] | summary [all ]]
  4. show interfaces
  5. show policy-map
  6. show ppp multilink
  7. show queueing

DETAILED STEPS

  Command or Action Purpose

Step 1

enable

Example:


Device> enable

Enables privileged EXEC mode.

  • Enter your password if prompted.

Step 2

show atm pvc

Example:


Device# show atm pvc

Displays all ATM PVCs and traffic information.

Step 3

show frame-relay pvc [[interface interface ] [dlci ] [64-bit ] | summary [all ]]

Example:


Device# show frame-relay pvc 16

Displays statistics about PVCs for Frame Relay interfaces.

Step 4

show interfaces

Example:


Device# show interfaces

Displays interleaving statistics.

  • Interleaving data is displayed only if interleaving occurs.

Step 5

show policy-map

Example:


Device# show policy-map

Displays the configuration of all classes for a specified service policy map or all classes for all existing policy maps.

Step 6

show ppp multilink

Example:


Device# show ppp multilink

Displays bundle information for the MLP bundles and their PPP links in the Device.

Step 7

show queueing

Example:


Device# show queueing

Lists all or selected configured queueing strategies.

Monitoring ATM Multilink PPP Support

SUMMARY STEPS

  1. enable
  2. debug atm errors
  3. debug atm events
  4. debug ppp error
  5. debug ppp multilink events
  6. debug voice rtp

DETAILED STEPS

  Command or Action Purpose

Step 1

enable

Example:


Device> enable

Enables privileged EXEC mode.

  • Enter your password if prompted.

Step 2

debug atm errors

Example:


Device# debug atm errors

Displays ATM errors.

Step 3

debug atm events

Example:


Device# debug atm events

Displays ATM events.

Step 4

debug ppp error

Example:


Device# debug ppp error

Displays information on traffic and exchanges in an internetwork implementing the PPP.

Step 5

debug ppp multilink events

Example:


Device# debug ppp multilink events

Displays information about events affecting multilink groups.

Step 6

debug voice rtp

Example:


Device# debug voice RTP

Displays information about the interleaving of voice and data packets.

  • The debug voice RTP command has memory overhead and should not be used when memory is scarce or when traffic is very high.

Configuration Examples for ATM Multilink PPP Support

Defining the Service Policy Using MQC Example

The following example shows how to configure a service policy using the MQC: 


Device> enable
Device# configure terminal
Device(config)# class-map match-all DATA
Device(config-cmap)# match ip precedence 0
Device(config-cmap)# class-map match-all VOICE
Device(config-cmap)# match access-group 100
Device(config-cmap)# policy-map CISCO
Device(config-pmap)# class VOICE
Device(config-pmap-c)# priority percent 70
Device(config-pmap-c)# class DATA
Device(config-pmap-c)# bandwidth percent 5
Device(config-pmap-c)# access-list 100 permit udp any any precedence critical

Defining a Multilink MLP Bundle Interface Example

The following example shows how to define a multilink bundle for the mulitilink interface: 


Device> enable
Device# configure terminal
Device(config)# interface Multilink1
Device(config-if)# ip address 10.2.1.1 255.0.0.0
Device(config-if)# load-interval 30
Device(config-if)# no cdp enable
Device(config-if)# service-policy output CISCO
Device(config-if)# ppp multilink fragment disable
Device(config-if)# ppp multilink group 1

Defining Virtual Templates for Member Links Example

The following example shows how to define virtual templates for member links: 


Device> enable
Device# configure terminal
Device(config)# interface Virtual-Template1
Device(config-if)# no ip address
Device(config-if)# load-interval 30
Device(config-if)# ppp multilink
Device(config-if)# ppp multilink group 1
Device(config-if)# interface Virtual-Template2
Device(config-if)# no ip address
Device(config-if)# load-interval 30
Device(config-if)# ppp multilink
Device(config-if)# ppp multilink group 1

Defining PVCs and Bundling Member Links Example

The following example shows how to define and configure PVCs as bundle members: 


Device> enable
Device# configure terminal
Device(config)# interface atm 6/0
Device(config-if)# no ip address
Device(config-if)# load-interval 30
Device(config-if)# atm ilmi-keepalive
Device(config-if)# pvc 0/34
 
Device(config-if-atm-vc)# vbr-nrt 1536 1536
Device(config-if-atm-vc)# tx-ring-limit 5
Device(config-if-atm-vc)# protocol ppp Virtual-Template1
Device(config-if-atm-vc)# pvc 0/35
 
Device(config-if-atm-vc)# vbr-nrt 800 800
Device(config-if-atm-vc)# tx-ring-limit 3
Device(config-if-atm-vc)# protocol ppp Virtual-Template2
Device(config-if-atm-vc)# pvc 0/36 
Device(config-if-atm-vc)# vbr-nrt 800 400 94
Device(config-if-atm-vc)# tx-ring-limit 5
Device(config-if-atm-vc)# protocol ppp Virtual-Template1
Device(config-if-atm-vc)# pvc 0/37
Device(config-if-atm-vc)# vbr-nrt 800 800
Device(config-if-atm-vc)# tx-ring-limit 3
Device(config-if-atm-vc)# protocol ppp Virtual-Template2
Device(config-if-atm-vc)# end

Additional References for ATM Multilink PPP Support on Multiple VCs

The following sections provide references related to the ATM Multilink PPP Support on Multiple VCs feature.

Related Documents

Related Topic

Document Title

QoS configuration tasks

Cisco IOS Quality of Service Solutions Configuration Guide

QoS commands: complete command syntax, defaults, command mode, command history, usage guidelines, and examples

Cisco IOS Quality of Service Solutions Command Reference

WAN configuration tasks

Cisco IOS Wide-Area Networking Configuration Guide

WAN commands: complete command syntax, defaults, command mode, command history, usage guidelines, and examples

Cisco IOS Wide-Area Networking Command Reference

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

RFC 1990

The PPP Multilink Protocol (MP)

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/cisco/web/support/index.html

Feature Information for ATM Multilink PPP Support

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 Multilink PPP Support on Multiple VCs

Feature Name

Releases

Feature Information

ATM Multilink PPP Support on Multiple VCs

12.2(28)SB 12.2(33)SRE

The ATM Multilink PPP Support on Multiple VCs feature facilitates traffic load balancing on high-speed virtual circuits, using MLP over Frame Relay and ATM. It facilitates traffic load balancing by using MLP to combine packet datagrams on high-speed VCs, as a means for transporting both the voice and data traffic more efficiently.

Glossary

LFI --link fragmentation and interleaving. Method of fragmenting large packets and then queueing the fragments between small packets.

MLP --multilink PPP.

QoS --quality of service.

VC --virtual circuit.