Contents

IPv6 Automatic 6to4 Tunnels

This feature provides support for IPv6 automatic 6to4 tunnels. An automatic 6to4 tunnel allows isolated IPv6 domains to be connected over an IPv4 network to remote IPv6 networks.

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.

Information About IPv6 Automatic 6to4 Tunnels

Automatic 6to4 Tunnels

An automatic 6to4 tunnel allows isolated IPv6 domains to be connected over an IPv4 network to remote IPv6 networks. The key difference between automatic 6to4 tunnels and manually configured tunnels is that the tunnel is not point-to-point; it is point-to-multipoint. In automatic 6to4 tunnels, routers are not configured in pairs because they treat the IPv4 infrastructure as a virtual nonbroadcast multiaccess (NBMA) link. The IPv4 address embedded in the IPv6 address is used to find the other end of the automatic tunnel.

An automatic 6to4 tunnel may be configured on a border router in an isolated IPv6 network, which creates a tunnel on a per-packet basis to a border router in another IPv6 network over an IPv4 infrastructure. The tunnel destination is determined by the IPv4 address of the border router extracted from the IPv6 address that starts with the prefix 2002::/16, where the format is 2002:border-router-IPv4-address ::/48. Following the embedded IPv4 address are 16 bits that can be used to number networks within the site. The border router at each end of a 6to4 tunnel must support both the IPv4 and IPv6 protocol stacks. 6to4 tunnels are configured between border routers or between a border router and a host.

The simplest deployment scenario for 6to4 tunnels is to interconnect multiple IPv6 sites, each of which has at least one connection to a shared IPv4 network. This IPv4 network could be the global Internet or a corporate backbone. The key requirement is that each site have a globally unique IPv4 address; the Cisco software uses this address to construct a globally unique 6to4/48 IPv6 prefix. As with other tunnel mechanisms, appropriate entries in a Domain Name System (DNS) that map between hostnames and IP addresses for both IPv4 and IPv6 allow the applications to choose the required address.

How to Configure IPv6 Automatic 6to4 Tunnels

Configuring Automatic 6to4 Tunnels

Perform this task to configure automatic 6to4 tunnels.

Before You Begin

With 6to4 tunnels, the tunnel destination is determined by the border router IPv4 address, which is concatenated to the prefix 2002::/16 in the format 2002:border-router-IPv4-address::/48. The border router at each end of a 6to4 tunnel must support both the IPv4 and IPv6 protocol stacks.


Note

The configuration of only one IPv4-compatible tunnel and one 6to4 IPv6 tunnel is supported on a router. If you choose to configure both of those tunnel types on the same router, we strongly recommend that they do not share the same tunnel source.

The reason that a 6to4 tunnel and an IPv4-compatible tunnel cannot share an interface is that both of them are NBMA "point-to-multipoint" access links and only the tunnel source can be used to reorder the packets from a multiplexed packet stream into a single packet stream for an incoming interface. So when a packet with an IPv4 protocol type of 41 arrives on an interface, that packet is mapped to an IPv6 tunnel interface based on the IPv4 address. However, if both the 6to4 tunnel and the IPv4-compatible tunnel share the same source interface, the router is not able to determine the IPv6 tunnel interface to which it should assign the incoming packet.

IPv6 manually configured tunnels can share the same source interface because a manual tunnel is a "point-to-point" link, and both the IPv4 source and IPv4 destination of the tunnel are defined.

>
SUMMARY STEPS

    1.    enable

    2.    configure terminal

    3.    interface tunnel tunnel-number

    4.    ipv6 address ipv6-prefix / prefix-length [eui-64]

    5.    tunnel source {ip-address| interface-t ype interface-number}

    6.    tunnel mode ipv6ip 6to4

    7.    exit

    8.    ipv6 route ipv6-prefix / prefix-length tunnel tunnel-number


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 tunnel tunnel-number


    Example:
    Router(config)# interface tunnel 0
     

    Specifies a tunnel interface and number, and enters interface configuration mode.

     
    Step 4 ipv6 address ipv6-prefix / prefix-length [eui-64]


    Example:
    Router(config-if)# ipv6 address 2002:c0a8:6301:1::1/64
     

    Specifies the IPv6 address assigned to the interface and enables IPv6 processing on the interface.

    • The 32 bits following the initial 2002::/16 prefix correspond to an IPv4 address assigned to the tunnel source.

     
    Step 5 tunnel source {ip-address| interface-t ype interface-number}


    Example:
    Router(config-if)# tunnel source ethernet 0
     

    Specifies the source interface type and number for the tunnel interface.

    Note   

    The interface type and number specified in the tunnel source command must be configured with an IPv4 address.

     
    Step 6 tunnel mode ipv6ip 6to4


    Example:
    Router(config-if)# tunnel mode ipv6ip 6to4
     

    Specifies an IPv6 overlay tunnel using a 6to4 address.

     
    Step 7 exit


    Example:
    Router(config-if)# exit
     

    Exits interface configuration mode, and returns the router to global configuration mode.

     
    Step 8 ipv6 route ipv6-prefix / prefix-length tunnel tunnel-number


    Example:
    

        
    
 

    Example:
    
          
    Router(config)# ipv6 route 2002::/16 tunnel 0
    

        
    
 
          		 
          
    
Configures a static route for the IPv6 6to4 prefix 2002::/16 to the specified tunnel interface. 
    

          
    Note   
                
              
    
When configuring a 6to4 overlay tunnel, you must configure a static route for the IPv6 6to4 prefix 2002::/16 to the 6to4 tunnel interface.
    

    

          
    • 
The tunnel number specified in the ipv6 route command must be the same tunnel number specified in the interface tunnelcommand.
      

      • 

    

         
      
    

    

    

    

    

    Configuration Examples for IPv6 Automatic 6to4 Tunnels
    

    

     
	 
    

    

    Example: Configuring 6to4 Tunnels
    

     
		
     The following example configures a 6to4 tunnel on a border router in an isolated IPv6 network. The IPv4 address is 192.168.99.1, which translates to the IPv6 prefix of 2002:c0a8:6301::/48. The IPv6 prefix is subnetted into 2002:c0a8:6301::/64 for the tunnel interface: 2002:c0a8:6301:1::/64 for the first IPv6 network, and 2002:c0a8:6301:2::/64 for the second IPv6 network. The static route ensures that any other traffic for the IPv6 prefix 2002::/16 is directed to tunnel interface 0 for automatic tunneling.
		
    
 
		
    interface Ethernet0
 description IPv4 uplink
 ip address 192.168.99.1 255.255.255.0
!
interface Ethernet1
 description IPv6 local network 1
 ipv6 address 2002:c0a8:6301:1::1/64 
!
interface Ethernet2
 description IPv6 local network 2
 ipv6 address 2002:c0a8:6301:2::1/64 
!
interface Tunnel0
 description IPv6 uplink
 no ip address
 ipv6 address 2002:c0a8:6301::1/64 
 tunnel source Ethernet 0
 tunnel mode ipv6ip 6to4
!
ipv6 route 2002::/16 tunnel 0
    
 
	 
    

    

    

    

    Additional References
    

    Related Documents
     
		 
		

    Related Topic 
				  
    
    		

    Document Title 
				  
    
    		

    
    

     
					 
     IPv6 addressing and connectivity 
					 
    
 
				      		
 
					 
     IPv6 Configuration Guide 
					 
    
 
				      		

    

     
					 
    Cisco IOS commands 
					 
    
 
				      		
 
					 
    Cisco IOS Master Commands List, All Releases 
					 
    
 
				      		

    

     
					 
    IPv6 commands 
					 
    
 
				      		
 
					 
    Cisco IOS IPv6 Command Reference 
					 
    
 
				      		

    

     
					 
    Cisco IOS IPv6 features 
					 
    
 
				      		

     
					 Cisco IOS IPv6 Feature Mapping 
					  
				  
    
    		

    
    

    

    
 
	 
    

    Standards and RFCs
     
		 
		

    Standard/RFC 
				  
    
    		

    Title 
				  
    
    		

    
    

     
					 
    RFCs for IPv6 
					 
    
 
				      		

    IPv6 RFCs 
				  
    
    		

    
    

    

    
 
	 
    

    MIBs
     
		 
		

     
					 
     MIB 
					 
    
 
				      		
 
					 
     MIBs Link 
					 
    
 
				      		

    
    

     
					 
     
					 
    
 
				      		
 
					 
     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 
					 
    
 
				      		

    
    

    

    
 
	 
    

    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 IPv6 Automatic 6to4 Tunnels
    

     
		
    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 IPv6 Automatic 6to4 Tunnels
    Feature Name 
			 
    
    		

    Releases 
			 
    
    		

    Feature Information 
			 
    
    		

    
    

     
				
    IPv6 Tunneling: Automatic 6to4 Tunnels 
				
    
 
			     		
 
				
    12.0(22)S 
				
    

				
    12.2(14)S 
				
    

				
    12.2(28)SB 
				
    

				
    12.2(33)SRA
				
    

				
    12.2(18)SXE
				
    

				
    12.2(2)T
				
    

				
    15.0(1)S
				
    
 
			     		
 
				
    An automatic 6to4 tunnel allows isolated IPv6 domains to be connected over an IPv4 network to remote IPv6 networks. 
				
    
 
				
    The following commands were introduced or modified: 
				  tunnel mode ipv6ip, 
				  tunnel source. 
				
    
 
			     		

    
    

    

    

    

    



    














IPv6 Automatic 6to4 Tunnels

                              

    


    IPv6 Automatic 6to4 Tunnels
    

    

    This feature provides support for IPv6 automatic 6to4 tunnels. An automatic 6to4 tunnel allows isolated IPv6 domains to be connected over an IPv4 network to remote IPv6 networks. 
	 
    

    

    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. 
	 
    

    

    

    Information About IPv6 Automatic 6to4 Tunnels
    

    

     
	 
    

    

    Automatic 6to4 Tunnels
    

     An automatic 6to4 tunnel allows isolated IPv6 domains to be connected over an IPv4 network to remote IPv6 networks. The key difference between automatic 6to4 tunnels and manually configured tunnels is that the tunnel is not point-to-point; it is point-to-multipoint. In automatic 6to4 tunnels, routers are not configured in pairs because they treat the IPv4 infrastructure as a virtual nonbroadcast multiaccess (NBMA) link. The IPv4 address embedded in the IPv6 address is used to find the other end of the automatic tunnel. 
	 
    

     An automatic 6to4 tunnel may be configured on a border router in an isolated IPv6 network, which creates a tunnel on a per-packet basis to a border router in another IPv6 network over an IPv4 infrastructure. The tunnel destination is determined by the IPv4 address of the border router extracted from the IPv6 address that starts with the prefix 2002::/16, where the format is 2002:border-router-IPv4-address ::/48. Following the embedded IPv4 address are 16 bits that can be used to number networks within the site. The border router at each end of a 6to4 tunnel must support both the IPv4 and IPv6 protocol stacks. 6to4 tunnels are configured between border routers or between a border router and a host. 
	 
    

     The simplest deployment scenario for 6to4 tunnels is to interconnect multiple IPv6 sites, each of which has at least one connection to a shared IPv4 network. This IPv4 network could be the global Internet or a corporate backbone. The key requirement is that each site have a globally unique IPv4 address; the Cisco software uses this address to construct a globally unique 6to4/48 IPv6 prefix. As with other tunnel mechanisms, appropriate entries in a Domain Name System (DNS) that map between hostnames and IP addresses for both IPv4 and IPv6 allow the applications to choose the required address. 
	 
    

    

    

    

    How to Configure IPv6 Automatic 6to4 Tunnels
    

    

     
	 
    

    

    Configuring Automatic 6to4 Tunnels
    

    
      
    
Perform this task to configure automatic 6to4 tunnels.
    

    
    

    Before You Begin
      
    
With 6to4 tunnels, the tunnel destination is determined by the border router IPv4 address, which is concatenated to the prefix 2002::/16 in the format 2002:border-router-IPv4-address::/48. The border router at each end of a 6to4 tunnel must support both the IPv4 and IPv6 protocol stacks.
    

      

    Note
    
        
    
The configuration of only one IPv4-compatible tunnel and one 6to4 IPv6 tunnel is supported on a router. If you choose to configure both of those tunnel types on the same router, we strongly recommend that they do not share the same tunnel source.
    

        
    
The reason that a 6to4 tunnel and an IPv4-compatible tunnel cannot share an interface is that both of them are NBMA "point-to-multipoint" access links and only the tunnel source can be used to reorder the packets from a multiplexed packet stream into a single packet stream for an incoming interface. So when a packet with an IPv4 protocol type of 41 arrives on an interface, that packet is mapped to an IPv6 tunnel interface based on the IPv4 address. However, if both the 6to4 tunnel and the IPv4-compatible tunnel share the same source interface, the router is not able to determine the IPv6 tunnel interface to which it should assign the incoming packet.
    

        
    
IPv6 manually configured tunnels can share the same source interface because a manual tunnel is a "point-to-point" link, and both the IPv4 source and IPv4 destination of the tunnel are defined.
    

>
    

    
    
SUMMARY STEPS
      1.   
      
          
            enable
          
        
      

      2.   
      
          
            configure
          
          
            terminal
          
        
      

      3.   
      
          
            interface
            tunnel
          
          
            tunnel-number
          
        
      

      4.   
      
          
            ipv6
            address
          
          
            
            
            ipv6-prefix
          
          
            /
          
          
            prefix-length
          [eui-64]
      

      5.   
      
          
            tunnel
            source
          {ip-address| interface-t ype interface-number}
      

      6.   
      
          
            tunnel
            mode
            ipv6ip
            6to4
          
        
      

      7.   
      
          
            exit
          
        
      

      8.   
      
          
            ipv6
            route
          
          
            
            
            ipv6-prefix
          
          
            /
          
          
            prefix-length
          
          
            tunnel
          
          
            tunnel-number
          
        
      


    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
            tunnel
          
          
            tunnel-number
          
        
       

      Example:
      
          
      Router(config)# interface tunnel 0
      

        
      
 
            		 
          
      
Specifies a tunnel interface and number, and enters interface configuration mode.
      

         
      
      

      Step 4
          
            ipv6
            address
          
          
            
            
            ipv6-prefix
          
          
            /
          
          
            prefix-length
          [eui-64]
       

      Example:
      
          
      Router(config-if)# ipv6 address 2002:c0a8:6301:1::1/64
      

        
      
 
            		 
          
      
Specifies the IPv6 address assigned to the interface and enables IPv6 processing on the interface.
      

          
      • 
The 32 bits following the initial 2002::/16 prefix correspond to an IPv4 address assigned to the tunnel source.
        

        • 

      

         
      
      

      Step 5
          
            tunnel
            source
          {ip-address| interface-t ype interface-number}
       

      Example:
      
          
      Router(config-if)# tunnel source ethernet 0
      

        
      
 
            		 
          
      
Specifies the source interface type and number for the tunnel interface.
      

          
      Note   
                
              
      
The interface type and number specified in the tunnel source command must be configured with an IPv4 address.
      

      

         
      
      

      Step 6
          
            tunnel
            mode
            ipv6ip
            6to4
          
        
       

      Example:
      
          
      Router(config-if)# tunnel mode ipv6ip 6to4
      

        
      
 
            		 
          
      
Specifies an IPv6 overlay tunnel using a 6to4 address.
      

         
      
      

      Step 7
          
            exit
          
        
       

      Example:
      
          
      Router(config-if)# exit
      

        
      
 
            		 
          
      
Exits interface configuration mode, and returns the router to global configuration mode.
      

         
      
      

      Step 8
          
            ipv6
            route
          
          
            
            
            ipv6-prefix
          
          
            /
          
          
            prefix-length
          
          
            tunnel
          
          
            tunnel-number
          
        
       

      Example:
      
          
      

        
      
 

      Example:
      
          
      Router(config)# ipv6 route 2002::/16 tunnel 0
      

        
      
 
            		 
          
      
Configures a static route for the IPv6 6to4 prefix 2002::/16 to the specified tunnel interface. 
      

          
      Note   
                
              
      
When configuring a 6to4 overlay tunnel, you must configure a static route for the IPv6 6to4 prefix 2002::/16 to the 6to4 tunnel interface.
      

      

          
      • 
The tunnel number specified in the ipv6 route command must be the same tunnel number specified in the interface tunnelcommand.
        

        • 

      

         
      
      

      

      

      

      

      Configuration Examples for IPv6 Automatic 6to4 Tunnels
      

      

       
	 
      

      

      Example: Configuring 6to4 Tunnels
      

       
		
       The following example configures a 6to4 tunnel on a border router in an isolated IPv6 network. The IPv4 address is 192.168.99.1, which translates to the IPv6 prefix of 2002:c0a8:6301::/48. The IPv6 prefix is subnetted into 2002:c0a8:6301::/64 for the tunnel interface: 2002:c0a8:6301:1::/64 for the first IPv6 network, and 2002:c0a8:6301:2::/64 for the second IPv6 network. The static route ensures that any other traffic for the IPv6 prefix 2002::/16 is directed to tunnel interface 0 for automatic tunneling.
		
      
 
		
      interface Ethernet0
 description IPv4 uplink
 ip address 192.168.99.1 255.255.255.0
!
interface Ethernet1
 description IPv6 local network 1
 ipv6 address 2002:c0a8:6301:1::1/64 
!
interface Ethernet2
 description IPv6 local network 2
 ipv6 address 2002:c0a8:6301:2::1/64 
!
interface Tunnel0
 description IPv6 uplink
 no ip address
 ipv6 address 2002:c0a8:6301::1/64 
 tunnel source Ethernet 0
 tunnel mode ipv6ip 6to4
!
ipv6 route 2002::/16 tunnel 0
      
 
	 
      

      

      

      

      Additional References
      

      Related Documents
       
		 
		

      Related Topic 
				  
      
      		

      Document Title 
				  
      
      		

      
      

       
					 
       IPv6 addressing and connectivity 
					 
      
 
				        		
 
					 
       IPv6 Configuration Guide 
					 
      
 
				        		

      

       
					 
      Cisco IOS commands 
					 
      
 
				        		
 
					 
      Cisco IOS Master Commands List, All Releases 
					 
      
 
				        		

      

       
					 
      IPv6 commands 
					 
      
 
				        		
 
					 
      Cisco IOS IPv6 Command Reference 
					 
      
 
				        		

      

       
					 
      Cisco IOS IPv6 features 
					 
      
 
				        		

       
					 Cisco IOS IPv6 Feature Mapping 
					  
				  
      
      		

      
      

      

      
 
	 
      

      Standards and RFCs
       
		 
		

      Standard/RFC 
				  
      
      		

      Title 
				  
      
      		

      
      

       
					 
      RFCs for IPv6 
					 
      
 
				        		

      IPv6 RFCs 
				  
      
      		

      
      

      

      
 
	 
      

      MIBs
       
		 
		

       
					 
       MIB 
					 
      
 
				        		
 
					 
       MIBs Link 
					 
      
 
				        		

      
      

       
					 
       
					 
      
 
				        		
 
					 
       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 
					 
      
 
				        		

      
      

      

      
 
	 
      

      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 IPv6 Automatic 6to4 Tunnels
      

       
		
      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 IPv6 Automatic 6to4 Tunnels
      Feature Name 
			 
      
      		

      Releases 
			 
      
      		

      Feature Information 
			 
      
      		

      
      

       
				
      IPv6 Tunneling: Automatic 6to4 Tunnels 
				
      
 
			       		
 
				
      12.0(22)S 
				
      

				
      12.2(14)S 
				
      

				
      12.2(28)SB 
				
      

				
      12.2(33)SRA
				
      

				
      12.2(18)SXE
				
      

				
      12.2(2)T
				
      

				
      15.0(1)S
				
      
 
			       		
 
				
      An automatic 6to4 tunnel allows isolated IPv6 domains to be connected over an IPv4 network to remote IPv6 networks. 
				
      
 
				
      The following commands were introduced or modified: 
				  tunnel mode ipv6ip, 
				  tunnel source.