Using Multilink PPP over Serial Interface Links

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 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.

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 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 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 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 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 (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
      

      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 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 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
        

         
	 
        

        

        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 
        

      
        

    
        

        

        

        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
        

         
		
         The following sections provide references related to using Multilink PPP over ATM 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
					 
        
 
				          		

        

         
					 
         Virtual template interfaces 
					 
        
 
				          		
 
					 
         "Configuring Virtual Template Interfaces" 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 dialer interface links
					 
        
 
				          		
 
					 
         "Using Multilink PPP over Dialer Interface 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 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 
		.
		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.