Using Multilink PPP over Serial Interface Links

Last Updated: December 9, 2011

This module tells you how to use Multilink PPP over serial interface links.


Note
As of Cisco IOS XE Software Release 2.1, Multilink PPP over serial interface links is the only Multilink PPP type supported. Multiclass MLPPP is not supported.

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 Table at the end of this document.

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 Serial Interface Links

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

Enable a queueing mechanism such as low latency queueing (LLQ), weighted fair queueing (WFQ), class-based WFQ (CBWFQ) and Weighted Random Early Detection (WRED), as applicable, before configuring multilink.

Restrictions for Using Multilink PPP over Serial Interface Links

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.

Only Voice over IP (VoIP) is supported.

As of Cisco IOS XE Release 2.1, Multilink PPP over serial interface links is the only Multilink PPP type supported. Multiclass MLPPP is not supported.

Information About Using Multilink PPP over Serial Interface Links

MQC and Multilink PPP over Serial Interface Links

Before using Multilink PPP over serial interface links, a traffic policy (policy map) must be created. Policy maps are created using the Modular Quality of Service (QoS) Command-Line Interface (CLI) (MQC).

How to Configure Multilink PPP over Serial Interface Links

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

Before You Begin

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.


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). 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). The policy map evaluates and applies QoS features for traffic enteringthe 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

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



Example:

 

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.

 
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

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 serial0/0/0

 

(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

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

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 
 
      
 
     
 
     
 
      
 
      
 
     
 
    
 
    
 
      
       
     
Example Associating the Serial Interface with the Multilink Group
 
     
 
      
 
        
         
       
 The following is an example of associating serial interface 4/1 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 
 
       
 
      
 
     
 
     
 
      
 
      
 
     
 
    
 
    
 
      
       
     
Example Verifying the Multilink PPP over Serial Interface Link Configuration
 
     
 
      
 
        
         
       
 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 showpppmultilink command only. For sample output of the other commands, see the Cisco IOS Quality of Service Solutions Command Reference. 
 
      
 
      
 
        
         
       
show ppp multilink Command Output Example
 
       
 The following is an example of the showpppmultilink command output. In this example, one multilink bundle called bundle-1 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 bundle-1
  Endpoint discriminator is bundle-1
  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)
 
      
 
     
 
     
 
      
 
      
 
     
 
    
 
   
 
   
 
     
      
    
Additional References
 
    
 
     
 
       
        
     
 
     
 
       
        
      
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 
 		 
         
 
         
 
           
 MQC 
 		 
           
 "Applying QoS Features Using the MQC" module 
 		 
         
 
         
 
           
 Multilink PPP overview 
 		 
           
 "Reducing Latency and Jitter for Real-Time Traffic Using Multilink PPP" 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 XE Software 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 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 Serial 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 Serial Interface Links 
         
 
         
       
 
       
 
         
         
 
           
 Feature Name 
 		 
           
 Software Releases 
 		 
           
 Feature Configuration Information 
 		 
         
 
         
         
         
 
           
 MLPPP QoS (CBWFQ, LLQ, WRED) 
 		 
           
 Cisco IOS XE Release 2.1 
 		 
           
 The MLPPP QoS feature implements Multilink PPP (MLPPP) using a distributed hierarchical queueing framework (HQF). The MLPPP QoS feature incorporates class-based weighted fair queueing (CBWFQ), low latency queueing (LLQ), and weighted random early detection (WRED) functionality. 
 		 
         
 
         
       
 
      
 
     
 
    
 
    
 
     
 
     
 
    
 
   
 
   
 
     
      
    
 
 
    
 
     
 
       
        
      
Cisco and the Cisco logo are trademarks or registered trademarks of Cisco and/or its affiliates in the U.S. and other countries. To view a list of Cisco trademarks, go to this URL: www.cisco.com/go/trademarks. Third-party trademarks mentioned 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. (1110R) 
 
      
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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