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.

Finding Feature Information

Your software release may not support all the features documented in this module. For the latest caveats and feature information, see Bug Search Tool and 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 table at the end of this module.

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.

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) 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

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.

How to Configure Multilink PPP over Dialer Interface Links

Configuring Multilink PPP over Dialer Interface Links

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

    10.    ppp chap hostname hostname

    11.    ppp chap password secret

    12.    ppp multilink [bap]

    13.    ppp multilink fragment delay milliseconds [microseconds]

    14.    ppp multilink interleave

    15.    end


DETAILED STEPS
     Command or ActionPurpose
    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 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 10 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 11 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 12 ppp multilink [bap]


    Example: 
    Router(config-if)# ppp multilink
     

    Enables multilink on an interface.

     
    Step 13 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 14 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 15 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 ActionPurpose
      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 ActionPurpose
        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)# 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

        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

        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 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.

        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.