DHCPv6 Individual Address Assignment

The Dynamic Host Configuration Protocol for IPv6 (DHCPv6) Individual Address Assignment feature manages nonduplicate address assignment in the correct prefix based on the network where the host is connected.

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Prerequisites for Configuring DHCPv6 Address Assignment

By default, no Dynamic Host Configuration Protocol for IPv6 (DHCPv6) features are configured on the device.

When you configure DHCPv6 address assignment, remember that the specified interface must be one of these Layer 3 interfaces:

  • Switch virtual interface (SVI): a VLAN interface created when you enter the interface vlan vlan-id command.

  • EtherChannel port channel in Layer 3 mode: a port-channel logical interface created when you enter the interface port-channel port-channel-number command.

Information About DHCPv6 Individual Address Assignment

DHCPv6 Address Assignment

Dynamic Host Configuration Protocol for IPv6 (DHCPv6) enables DHCP servers to pass configuration parameters, such as IPv6 network addresses, to IPv6 clients. The DHCPv6 Individual Address Assignment feature manages nonduplicate address assignment in the correct prefix based on the network where the host is connected. Assigned addresses can be from one or multiple prefix pools. Additional options, such as the default domain and Domain Name System (DNS) name-server address, can be passed back to the client. Address pools can be assigned for use on a specific interface or on multiple interfaces, or the server can automatically find the appropriate pool.

How to Configure DHCPv6 Individual Address Assignment

Enabling the DHCPv6 Server Function on an Interface

Perform this task to enable the Dynamic Host Configuration Protocol for IPv6 (DHCPv6) server function on an interface. Note that to delete a DHCPv6 pool, you must use the no ipv6 dhcp pool poolname global configuration command. Use the no form of the DHCP pool configuration mode commands to change the DHCPv6 pool characteristics. To disable the DHCPv6 server function on an interface, use the no ipv6 dhcp server interface configuration command.

SUMMARY STEPS

    1.    enable

    2.    configure terminal

    3.    ipv6 dhcp pool poolname

    4.    address prefix ipv6-prefix [lifetime {valid-lifetime preferred-lifetime | infinite}]

    5.    link-address ipv6-prefix

    6.    vendor-specific vendor-id

    7.    suboption number {address ipv6-address | ascii ascii-string | hex hex-string}

    8.    exit

    9.    exit

    10.    interface type number

    11.    ipv6 dhcp server [poolname | automatic] [rapid-commit] [preference value] [allow-hint]

    12.    end

    13.    Do one of the following:

    • show ipv6 dhcp pool
    • show ipv6 dhcp interface

    14.    copy running-config startup-config


DETAILED STEPS
     Command or ActionPurpose
    Step 1 enable


    Example:
    Device> enable
     

    Enables privileged EXEC mode.

    • Enter your password if prompted.

     
    Step 2 configure terminal


    Example:
    Device(config)# configure terminal
     

    Enters global configuration mode.

     
    Step 3 ipv6 dhcp pool poolname


    Example:
    Device(config)# ipv6 dhcp pool engineering
     

    Enters DHCP for IPv6 pool configuration mode, and defines the name of the IPv6 DHCP pool.

     
    Step 4 address prefix ipv6-prefix [lifetime {valid-lifetime preferred-lifetime | infinite}]


    Example:
    Device(config-dhcpv6)# address prefix 2001:1000::0/64 lifetime infinite
     

    (Optional) Specifies an address prefix for address assignment.

    • This address must be in hexadecimal, using 16-bit values between colons.

    • lifetime valid-lifetime preferred-lifetime—Specifies a time interval (in seconds) that an IPv6 address prefix remains in the valid state.

     
    Step 5 link-address ipv6-prefix


    Example:
    Device(config-dhcpv6)# link-address 2001:1001::0/64
     

    (Optional) Specifies a link-address IPv6 prefix.

    • When an address on the incoming interface or a link address in the packet matches the specified IPv6 prefix, the server uses the configuration information pool.

     
    Step 6 vendor-specific vendor-id


    Example:
    Device(config-dhcpv6)# vendor-specific 9
     

    (Optional) Enters DHCPv6 vendor-specific configuration mode with the vendor-specific identification number.

     
    Step 7 suboption number {address ipv6-address | ascii ascii-string | hex hex-string}


    Example:
    Device(config-dhcpv6-vs)# suboption 1 address 1000:235D::1
     

    (Optional) Enters a vendor-specific suboption number.

     
    Step 8 exit


    Example:
    Device(config-dhcpv6-vs)# exit
     

    Returns to DHCP pool configuration mode.

     
    Step 9 exit


    Example:
    Device(config-dhcpv6)# exit
     

    Returns to global configuration mode.

     
    Step 10 interface type number


    Example:
    Device(config)# interface fastethernet 0/0
     

    Enters interface configuration mode, and specifies the interface to configure.

     
    Step 11 ipv6 dhcp server [poolname | automatic] [rapid-commit] [preference value] [allow-hint]


    Example:
    Device(config-if)# ipv6 dhcp server rapid-commit
     

    Enables the DHCPv6 server function on an interface.

     
    Step 12 end


    Example:
    Device(config-if)# end
     

    Returns to privileged EXEC mode.

     
    Step 13Do one of the following:
    • show ipv6 dhcp pool
    • show ipv6 dhcp interface


    Example:
    Device# show ipv6 dhcp pool
     

    Verifies DHCPv6 pool configuration or verifies that the DHCPv6 server function is enabled on an interface.

     
    Step 14 copy running-config startup-config


    Example:
    Device# copy running-config startup-config
     

    (Optional) Saves your entries in the configuration file.

     

    Enabling the DHCPv6 Client Function on an Interface

    Perform this task to enable the Dynamic Host Configuration Protocol for IPv6 (DHCPv6) client function on an interface. To disable the DHCPv6 client function, use the no ipv6 address dhcp interface configuration command. To remove the DHCPv6 client request, use the no ipv6 address dhcp client request vendor interface configuration command.

    SUMMARY STEPS

      1.    enable

      2.    configure terminal

      3.    interface type number

      4.    ipv6 address dhcp [rapid-commit]

      5.    ipv6 address dhcp client request vendor

      6.    end

      7.    show ipv6 dhcp interface


    DETAILED STEPS
       Command or ActionPurpose
      Step 1 enable


      Example:
      Device> enable
       

      Enables privileged EXEC mode.

      • Enter password if prompted.

       
      Step 2 configure terminal


      Example:
      Device# configure terminal
       

      Enters global configuration mode.

       
      Step 3 interface type number


      Example:
      Device(config)# interface fastethernet 0/0
       

      Enters interface configuration mode, and specifies the interface to configure.

       
      Step 4 ipv6 address dhcp [rapid-commit]


      Example:
      Device(config-if)# ipv6 address dhcp rapid-commit
       

      Enables the interface to acquire an IPv6 address from the DHCPv6 server.

       
      Step 5 ipv6 address dhcp client request vendor


      Example:
      Device(config-if)# ipv6 adress dhcp client request vendor
       

      (Optional) Enables the interface to request the vendor-specific option.

       
      Step 6 end


      Example:
      Device(config-if)# end
       

      Returns to privileged EXEC mode.

       
      Step 7 show ipv6 dhcp interface


      Example:
      Device# show ipv6 dhcp interface
       

      Verifies that the DHCPv6 client is enabled on an interface.

       

      Configuration Examples for DHCPv6 Individual Address Assignment

      Examples: Configuring the DHCPv6 Server Function

      In the following example, Dynamic Host Configuration Protocol for IPv6 (DHCPv6) clients are connected to the DHCPv6 server on Ethernet interface 0/0. The server is configured to use parameters from the DHCP pool called dhcp-pool. This pool provides clients with the IPv6 address of a Domain Name System (DNS) server and the domain name to be used. It also specifies that prefixes can be delegated from the prefix pool called client-prefix-pool1. The prefixes delegated will have valid and preferred lifetimes of 1800 and 600 seconds, respectively. The prefix pool named client-prefix-pool1 has a prefix of length /40 from which it will delegate (sub) prefixes of length /48. 

      ipv6 dhcp pool dhcp-pool
 prefix-delegation pool client-prefix-pool1 lifetime 1800 600
 dns-server 2001:DB8:3000:3000::42
 domain-name example.com
!
interface Ethernet 0/0
 description downlink to clients
 ipv6 address FEC0:240:104:2001::139/64
 ipv6 dhcp server dhcp-pool
!
ipv6 local pool client-prefix-pool1 2001:DB8:1200::/40 48

      The following example from the show ipv6 dhcp command shows the DHCP unique identifier (DUID) of the device: 

      Device# show ipv6 dhcp 

This device's DHCPv6 unique identifier(DUID): 000300010002FCA5DC1C

      In the following example, the show ipv6 dhcp binding command shows information about two clients, including their DUIDs, IAPDs, prefixes, and preferred and valid lifetimes: 

      Device# show ipv6 dhcp binding

Client: FE80::202:FCFF:FEA5:DC39 (Ethernet2/1)
  DUID: 000300010002FCA5DC1C
  IA PD: IA ID 0x00040001, T1 0, T2 0
    Prefix: 3FFE:C00:C18:11::/68
            preferred lifetime 180, valid lifetime 12345
            expires at Nov 08 2002 02:24 PM (12320 seconds)
Client: FE80::202:FCFF:FEA5:C039 (Ethernet2/1)
  DUID: 000300010002FCA5C01C
  IA PD: IA ID 0x00040001, T1 0, T2 0
    Prefix: 3FFE:C00:C18:1::/72
            preferred lifetime 240, valid lifetime 54321
            expires at Nov 09 2002 02:02 AM (54246 seconds)
    Prefix: 3FFE:C00:C18:2::/72
            preferred lifetime 300, valid lifetime 54333
            expires at Nov 09 2002 02:03 AM (54258 seconds)
    Prefix: 3FFE:C00:C18:3::/72
            preferred lifetime 280, valid lifetime 51111

      In the following example, the show ipv6 dhcp database command provides information on the binding database agents TFTP, NVRAM, and flash: 

      Device# show ipv6 dhcp database 

Database agent tftp://172.19.216.133/db.tftp:
  write delay: 69 seconds, transfer timeout: 300 seconds
  last written at Jan 09 2003 01:54 PM,
     write timer expires in 56 seconds
  last read at Jan 06 2003 05:41 PM
  successful read times 1
  failed read times 0
  successful write times 3172
  failed write times 2
Database agent nvram:/dhcpv6-binding:
  write delay: 60 seconds, transfer timeout: 300 seconds
  last written at Jan 09 2003 01:54 PM,
     write timer expires in 37 seconds
  last read at never
  successful read times 0
  failed read times 0
  successful write times 3325
  failed write times 0
Database agent flash:/dhcpv6-db:
  write delay: 82 seconds, transfer timeout: 3 seconds
  last written at Jan 09 2003 01:54 PM,
    write timer expires in 50 seconds
  last read at never
  successful read times 0
  failed read times 0
  successful write times 2220
  failed write times 614

      Example: Configuring the DHCPv6 Client Function

      In the following example, this Dynamic Host Configuration Protocol for IPv6 (DHCPv6) client has three interfaces. Ethernet interface 0/0 is the upstream link to a service provider, which has a DHCPv6 server function enabled. The Fast Ethernet interfaces 0/0 and 0/1 are links to local networks.

      The upstream interface, Ethernet interface 0/0, has the DHCPv6 client function enabled. Prefixes delegated by the provider are stored in the general prefix called prefix-from-provider.

      The local networks, Fast Ethernet interfaces 0/0 and 0/1, both assign interface addresses based on the general prefix called prefix-from-provider. The bits on the left of the addresses come from the general prefix, and the bits on the right of the addresses are specified statically. 

      interface Ethernet 0/0
 description uplink to provider DHCP IPv6 server
 ipv6 dhcp client pd prefix-from-provider
!
interface FastEthernet 0/0
 description local network 0
 ipv6 address prefix-from-provider ::5:0:0:0:100/64
!
interface FastEthernet 0/1
 description local network 1
 ipv6 address prefix-from-provider ::6:0:0:0:100/64

      Additional References

      Related Documents

      Related Topic

      Document Title

      IPv6 addressing and connectivity

      IPv6 Configuration Guide

      Cisco IOS commands

      Cisco IOS Master Command List, All Releases

      IPv6 commands

      Cisco IOS IPv6 Command Reference

      Cisco IOS IPv6 features

      IPv6 Feature Mapping

      Standards and RFCs

      Standard/RFC

      Title

      RFCs for IPv6

      IPv6 RFCs

      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 DHCPv6 Individual Address Assignment

      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 DHCPv6 Individual Address Assignment

      Feature Name

      Releases

      Feature Information

      DHCPv6 Individual Address Assignment

      Cisco IOS XE Release 3.2SE

      The DHCPv6 Individual Address Assignment feature manages nonduplicate address assignment in the correct prefix based on the network where the host is connected.

      The following commands were introduced or modified: clear ipv6 dhcp bindings, debug ipv6 dhcp, ipv6 address dhcp, ipv6 dhcp pool, show ipv6 dhcp bindings, show ipv6 dhcp interface, show ipv6 dhcp pool.