PPPoE on ATM

This feature module describes the PPP over Ethernet (PPPoE) on ATM feature. The PPPoE on ATM feature provides the ability to connect a network of hosts over a simple bridging-access device to a remote access concentrator.

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 PPPoE on ATM

Before you can configure PPPoE on ATM, you need to specify a virtual template for the PPPoE sessions using the virtual-template command.

Restrictions for PPPoE on ATM

  • PPPoE is not supported on Frame Relay.

  • PPPoE over ATM AAl5Mux is not supported on ASR series 1000 routers. For more information, refer to the PPPoEoA over ATM AAL5Mux feature: http://www.cisco.com/en/US/docs/ios/bbdsl/configuration/guide/bba_pppoeoa_aal5mux.html

  • PPPoE is not supported on any other LAN interfaces such as FDDI and Token Ring.

  • Fast switching is supported. PPPoE over RFC 1483 fibswitching is supported for IP. All other protocols are switched over process switching.

  • Bridging is supported on the ATM permanent virtual connections (PVCs) running PPPoE.

  • PPPoE is supported on ATM PVCs compliant with RFC 1483 only.

  • Only dial-in mode is supported. Dial-out mode will not be supported.

Information About PPPoE on ATM

The PPPoE on ATM feature provides the ability to connect a network of hosts over a simple bridging-access device to a remote access concentrator. With this model, each host utilizes its own PPPoE stack and the user is presented with a familiar user interface. Access control, billing and type of service can be done on a per-user, rather than a per-site, basis. Before a point-to-point connection over Ethernet can be provided, each PPP session must learn the Ethernet address of the remote peer and establish a unique session identifier. A unique session identifier is provided by the PPPoE Discovery Stage protocol.

The figure below shows a sample network topology using PPPoE on ATM.

Figure 1. PPPoE on ATM Sample Network Topology

PPPoE Stage Protocols

PPPoE has two distinct stage protocols. The stage protocols are listed and summarized in the table below.

Table 1 PPPoE Stage Protocols

Stage Protocols

Description

Discovery Stage protocol

Remains stateless until a PPPoE session is established. Once the PPPoE session is established, both the host and the access concentrator must allocate the resources for a PPP virtual access interface.

PPP Session Stage protocol

Once the PPPoE session is established, sends PPPoE data as in any other PPP encapsulation.

There are four steps to the Discovery Stage:

  1. Host broadcasts a PPPoE Active Discovery Initiation (PADI) packet.

  2. When the access concentrator receives a PADI that it can serve, it replies by sending a PPPoE Active Discovery Offer (PADO) packet to the host.

  3. Because the PADI was broadcast, the host may receive more than one PADO packet. The host looks through the PADO packets it receives and chooses one. The choice can be based on the AC name or the services offered. The host then sends a single PPPoE Active Discovery Request (PADR) packet to the access concentrator that it has chosen.

  4. When the access concentrator receives a PADR packet, it prepares to begin a PPP session. It generates a unique SESSION_ID for the PPPoE session and replies to the host with a PPPoE Active Discovery Session-confirmation (PADS) packet.

When a host wishes to initiate a PPPoE session, it must first perform discovery to identify the Ethernet MAC address of the peer and establish a PPPOE SESSION_ID. Although PPP defines a peer-to-peer relationship, discovery is inherently a client/server relationship. In the discovery process, a host (the client) discovers an access concentrator (the server). Based on the network topology, there may be more than one access concentrator that the host can communicate with. The Discovery Stage allows the host to discover all access concentrators and then select one. When discovery is completed, both the host and the selected access concentrator have the information they will use to build their point-to-point connection over Ethernet.

Benefits of PPPoE on ATM

The PPPoE on ATM feature provides service-provider digital subscriber line (DSL) support. As service providers begin DSL deployments, two of their most significant goals are to ease and facilitate consumer end adoption and to preserve as much of the dialup model as possible. PPPoE serves to advance both of these goals by leveraging ethernet scale curves and embedded base (such as ATM NICs) and by preserving the point-to-point session used by internet service providers (ISPs) in today’s dialup model.

Using a PPPoE client (available from RouterWare), a PPP session can be initiated on an Ethernet connected client through a standard ADSL modem. The session is transported over the ATM DSL link via RFC 1483 Ethernet bridged frames and can terminate either in the LAN emulation client (LEC) central office or the ISP point of presence (POP). The termination device can be an aggregation box such as the Cisco 6400 or a router such as the Cisco 7200 series platforms.

As customers deploy asymmetric DSL (ADSL), they will encounter the need to enable users to access remote-access concentrators via simple bridges connecting Ethernet and ATM networks.

How to Configure PPPoE on ATM

Enabling PPP over ATM

After you configure the Cisco router or access server for Ethernet encapsulation, you must configure the physical interface with the PVC and apply a virtual template with PPP encapsulation to the PVC that it applies to. To configure the physical interface that will carry the PPPoE session and link it to the appropriate virtual template interface, use the following commands:


Note

You can use the virtual-template, sessions per-vc, and sessions per-mac commands in any order.

SUMMARY STEPS

    1.    enable

    2.    configure terminal

    3.    bba-group pppoe {group-name | global}

    4.    virtual-template template-number

    5.    sessions per-vc limit per-vc-limit [threshold threshold-value]

    6.    sessions per-mac limit per-mac-limit

    7.    exit

    8.    interface atm slot / subslot / port [.subinterface][point-to-point | multipoint]

    9.    ip address ip-address mask [secondary]

    10.    range [range-name] pvc start-vpi / start-vci end-vpi / end-vci

    11.    dbs enable [aggregated | maximum]

    12.    Do one of the following:

    • protocol pppoe group {group-name | global}
    • or
    • encapsulation aal5snap

    13.    create on-demand

    14.    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 bba-group pppoe {group-name | global}


    Example:
    Router(config)# bba-group pppoe pppoe-group
     

    Defines a PPPoE profile, and enters BBA group configuration mode.

    • The global keyword creates a profile that serves as the default profile for any PPPoE port that is not assigned a specific profile.

     
    Step 4 virtual-template template-number


    Example:
    Router(config-bba-group)# virtual-template 1
     

    Specifies which virtual template will be used to clone virtual access interfaces.

     
    Step 5 sessions per-vc limit per-vc-limit [threshold threshold-value]


    Example:
    Router(config-bba-group)# sessions max limit 1
     

    Configures the PPPoE global profile with the maximum number of PPPoE sessions permitted on a router and sets the PPPoE session-count threshold at which an Simple Network Management Protocol (SNMP) trap will be generated.

    Note   

    This command applies only to the global profile.

     
    Step 6 sessions per-mac limit per-mac-limit


    Example:
    Router(config-bba-group)# sessions per-mac limit 4000
     

    Sets the maximum number of PPPoE sessions permitted per MAC address in a PPPoE profile.

     
    Step 7 exit


    Example:
    Router(config-bba-group)# exit
     

    Exits BBA group configuration mode and returns to global configuration mode.

     
    Step 8 interface atm slot / subslot / port [.subinterface][point-to-point | multipoint]


    Example:
    Router(config)# interface atm 1/0.1 multipoint
     

    Specifies the ATM interface and enters subinterface configuration mode.

     
    Step 9 ip address ip-address mask [secondary]


    Example:
    Router(config-subif)# ip address 192.0.10.2 255.255.255.0 secondary
     

    Sets a primary or secondary IP address for an interface.

     
    Step 10 range [range-name] pvc start-vpi / start-vci end-vpi / end-vci


    Example:
    Router(config-if)# range pvc 101/304 200/400
     

    Defines a range of ATM permanent virtual circuits (PVCs) and enters ATM range configuration mode.

     
    Step 11 dbs enable [aggregated | maximum]


    Example:
    Router(config-if-atm-range)# dbs enable
     

    Applies the Dynamic Subscriber Bandwidth Selection (DBS) QoS parameters.

     
    Step 12Do one of the following:
    • protocol pppoe group {group-name | global}
    • or
    • encapsulation aal5snap


    Example:
    Router(config-if-atm-range-pvc)# protocol pppoe group two


    Example:
    

        
    
 

    Example:
    
          
              
    

        
    
 

    Example:
    
          
    Router(config-if-atm-range-pvc)# encapsulation aal5snap
    

        
    
 
          		 
          
    
Enables PPPoE sessions to be established on a PVC within a range.
    

          
    
or
    

          
    
Configures PPPoE autosense. 
    

          
    • 
If a PPPoE profile is not assigned to the PVC by using the group group-name option, the PVC will use the global PPPoE profile.
      

      • 

    

         
      
    

    Step 13
          
            create
            on-demand
          
        
     

    Example:
    
          
    Router(config-if-atm-range)# create on-demand
    

        
    
 
          		 
          
    
Configures ATM PVC autoprovisioning, which enables a range of PVCs to be created automatically on demand. 
    

         
      
    

    Step 14
          
            end
          
        
     

    Example:
    
          
    Router(config-if-atm-range)# end
    

        
    
 
          		 
          
    
(Optional) Exits the ATM range configuration mode and returns to privileged EXEC mode.
    

         
      
    

    

    

    

    Creating and Configuring a Virtual Template
    

    

    

    Specifying an ATM Subinterface
    

    
      
    
After you create a virtual template for PPPoE on ATM, specify a multipoint or point-to-point subinterface per PVC connection. To specify an ATM multipoint subinterface, use the following commands:
    

    
    
SUMMARY STEPS
      1.   
      
          
            enable
          
        
      

      2.   
      
          
            configure
            terminal
          
        
      

      3.   
      
          
            interface
            atm
          
          
            
            
          
          
            slot
          
          
            /
          
          
            subslot
          
          
            /
          
          
            port
          
          
            .subinterface
          ] [multipoint| point-to-point]
      

      4.   
      
          
            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
            atm
          
          
            
            
          
          
            slot
          
          
            /
          
          
            subslot
          
          
            /
          
          
            port
          
          
            .subinterface
          ] [multipoint| point-to-point]
       

      Example:
      
          
      Router# interface atm 6/0.110 multipoint
      

        
      
 
            		 
          
      
Configures the ATM interface and enters subinterface configuration mode.
      

          
      • 
A multipoint subinterface is recommended for interface conservation. A point-to-point subinterface will greatly restrict the total number of PPPoE sessions you can have.
        

        • 

      

         
      
      

      Step 4
          
            end
          
        
       

      Example:
      
          
      Router(config-subif)# end
      

        
      
 
            		 
          
      
(Optional) Exits the subinterface configuration mode and returns to privileged EXEC mode.
      

         
      
      

      

      

      

      Creating an ATM PVC
      

      

      

      Enabling PPPoE on an ATM PVC
      

      
      
       To enable PPPoE on an ATM PVC, use the following commands:
		
      

    
      
SUMMARY STEPS
        1.   
      
          
            enable
          
        
        

        2.   
      
          
            configure
            terminal
          
        
        

        3.   
      
          
            interface
            atm
          
          
            slot
          
          
            /
          
          
            subslot
          
          
            /
          
          
            port
          [.subinterface]
			 [multipoint | 
			 point-to-point]
		  
        

        4.   
      
          
            pvc
           [name] 
			 vpi / vci
        

        5.   
      
          
            pppoe
            max-sessions
          
          
            number-of-sessions
          
			 [threshold-sessions number-of-sessions]
		  
        

        6.   
      
          
            protocol
            pppoe
          
        
        

        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
            atm
          
          
            slot
          
          
            /
          
          
            subslot
          
          
            /
          
          
            port
          [.subinterface]
			 [multipoint | 
			 point-to-point]
		  
         

        Example:
        
          
        Router(config)# interface atm 0/0/0.3 multipoint
        

        
        
 
              		 
          
         Configures the ATM interface and enters the subinterface
				configuration mode.
			 
        

         
      
        

        Step 4
          
            pvc
           [name] 
			 vpi / vci
         

        Example:
        
          
        Router(config-subif)# pvc 5/120
        

        
        
 
              		 
          
         Creates an ATM PVC and enters ATM VC configuration mode.
			 
        

         
      
        

        Step 5
          
            pppoe
            max-sessions
          
          
            number-of-sessions
          
			 [threshold-sessions number-of-sessions]
		  
         

        Example:
        
          
        Router(config-if-atm-vc)# pppoe max-sessions 5 threshold-sessions 3
        

        
        
 
              		 
          
         Sets the maximum number of PPPoE sessions that will be permitted
				on an ATM PVC, PVC range, VC class, or VLAN, and sets the PPPoE session-count
				threshold at which an SNMP trap will be generated.
			 
        

         
      
        

        Step 6
          
            protocol
            pppoe
          
        
         

        Example:
        
          
        Router(config-if-atm-vc)# protocol pppoe
        

        
        
 
              		 
          
         Enables PPPoE sessions to be established on ATM PVCs. 
			 
        

         
      
        

        Step 7
          
            end
          
        
         

        Example:
        
          
        Router(config-if-atm-vc)# end
        

        
        
 
              		 
          
         (Optional) Exits the ATM VC configuration mode and returns to
				privileged EXEC mode. 
			 
        

         
      
        

        

        

        

        

        Configuration Examples for PPPoE on ATM
        

        

        PPPoE on ATM   Example
        

        
The following example configures PPPoE on ATM to accept dial-in PPPoE sessions. The virtual access interface for the PPP session is cloned form virtual template interface 1. On subinterface ATM 2/0.1, ATM PVC with VPI 0 and VCI 60 is configured with Logical Link Control (LLC)/Subnetwork Access Protocol (SNAP) encapsulation and is configured to run PPPoE.
        

        bba-group pppoe pppoe-group 
 virtual-template 1
 sessions per-vc limit 1
 sessions per-mac limit 4000
interface atm 2/0.1 multipoint
 ip address 192.0.10.2 255.255.255.0 secondary
 range pvc 1/100 1/202
 pvc 0/60
  dbs enable
  encapsulation aal5snap
  protocol pppoe group two
  create on-demand
interface virtual-template 1
  ip addr 10.0.1.2 255.255.255.0
  mtu 1492

        

        

        

        

        Where to Go Next
        

        •  If you want to enable PPP authentication on the virtual template using the 
		  ppp 
			 authentication 
			 chap command, refer to the "Configuring Virtual Template Interfaces" chapter in the 
		  Cisco IOS Dial Solutions Configuration Guide .
		
          

          • 

        •  If you want to configure an authentication, authorization, and accounting (AAA) server, refer to the "Configuring per-User Configuration" chapter in the 
		  Cisco IOS Dial Solutions Configuration Guide .
		
          

          • 

        

        

        

        Additional References
        

         
		
         The following sections provide references related to the PPPoE on ATM feature.
		
        
 
	 
        

        Related Documents
         
		 
		

         
					 
         Related Topic
					 
        
 
				          		
 
					 
         Document Title
					 
        
 
				          		

        
        

         
					 
         Cisco IOS commands
					 
        
 
				          		
 
					 
         
						Cisco IOS Master Commands List, All Releases 
					 
        
 
				          		

        

         
					 
         Broadband and DSL commands
					 
        
 
				          		
 
					 
        Cisco IOS Broadband Access Aggregation and DSL Command Reference 
					 
        
 
				          		

        

         
					 
         Enabling PPP authentication on the virtual template
					 
        
 
				          		
 
					 
         Configuring Virtual Template Interfaces 
					 
        
 
				          		

        

         
					 
         Configuring an AAA server
					 
        
 
				          		
 
					 
         Configuring per-User Configuration 
					 
        
 
				          		

        

         
					 
         Configuring Broadband and DSL
					 
        
 
				          		
 
					 
        Cisco IOS XE Broadband Access Aggregation and DSL Configuration Guide 
					 
        
 
				          		

        
        

        

        
 
	 
        

        Standards
         
		 
		

         
					 
         Standard
					 
        
 
				          		
 
					 
         Title
					 
        
 
				          		

        
        

         
					 
         None
					 
        
 
				          		
 
					 
         --
					 
        
 
				          		

        

         
					 
         
					 
        
 
				          		
 
					 
         
					 
        
 
				          		

        
        

        

        
 
	 
        

        MIBs
         
		 
		

         
					 
         MIB
					 
        
 
				          		
 
					 
         MIBs Link
					 
        
 
				          		

        
        

         
					 
         
					 
        
 
				          		
 
					 
         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 1483
					 
        
 
				          		
 
					 
         
						Multiprotocol Encapsulation over ATM Adaptation Layer 5 
					 
        
 
				          		

        

         
					 
         RFC 2364
					 
        
 
				          		
 
					 
         
						PPP over AAL5 
					 
        
 
				          		

        

         
					 
         RFC 2516
					 
        
 
				          		
 
					 
         
						A Method for Transmitting PPP over Ethernet (PPPoE) 
					 
        
 
				          		

        
        

        

        
 
	 
        

        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 PPPoE on ATM
        

        
			
        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 2 Feature Information for PPPoE on ATM 
         
				  
         Feature Name 
				  
        
 
				        		
 
				  
         Releases 
				  
        
 
				        		
 
				  
         Feature Information 
				  
        
 
				        		

        
        

         
				  
         PPPoE on ATM 
				  
        
 
				        		
 
				  
         Cisco IOS XE Release 2.5 
				  
        
 
				        		
 
				  
        This feature was introduced on Cisco ASR 1000 Series Aggregation Services Routers. 
				  
        
 
				  
        This feature module describes the PPP over Ethernet (PPPoE) on ATM feature. The PPPoE on ATM feature provides the ability to connect a network of hosts over a simple bridging-access device to a remote access concentrator. 
				  
        
 
				  
         The following commands were introduced or modified: 
					 bba-group, 
						protocol 
						(VPDN), 
					 virtual-template. 
				  
        
 
				        		

        
        

        

        
 
	 
        

        

        

        Glossary
        

        
      
        AAL5
      --ATM Adaptation Layer 5
        

        
      
        ADSL
      --Asymmetric Digital Subscriber Line
        

        
      
        ATM
      --Asynchronous Transfer Mode
        

        
      
        CPCS
      --Common Part of Convergence Sublayer
        

        
      
        CPI
      --Common Part Indicator
        

        
      
        CRC
      --Cyclic Redundancy Check
        

        
      
        DSLAM
      --Digital Subscriber Line Access Multiplexer
        

        
      
        FCS
      --Frame Check Sequence
        

        
      
        IETF
      --Internet Engineering Task Force
        

        
      
        ID
      -Identifier
        

        
      
        IP
      --Internet Protocol
        

        
      
        L2TP
      --Layer two Tunneling Protocol
        

        
      
        LAN
      --Local Area Network
        

        
      
        LLC
      --Logical Link Control
        

        
      
        MAC
      --Media Access Control
        

        
      
        PDU
      --Protocol Data Unit
        

        
      
        PPP
      --Point to Point Protocol
        

        
      
        PPPoE
      --Point to Point Protocol over Ethernet
        

        
      
        PVC
      --Permanent Virtual Connection
        

        
      
        VPDN
      --Virtual Private Dialup Network