DHCPv6 Relay—Lightweight DHCPv6 Relay Agent

The DHCPv6 Relay—Lightweight DHCPv6 Relay Agent feature allows relay agent information to be inserted by an access node that performs a link-layer bridging (non-routing) function. Lightweight DHCPv6 Relay Agent (LDRA) functionality can be implemented in existing access nodes, such as DSL access multiplexers (DSLAMs) and Ethernet switches, that do not support IPv6 control or routing functions. LDRA is used to insert relay-agent options in DHCP version 6 (DHCPv6) message exchanges primarily to identify client-facing interfaces. LDRA functionality can be enabled on an interface and on a VLAN.

An LDRA device or interface has the following features:

  • Maintains interoperability with existing DHCPv6 relay agents and servers.

  • Is functionally the equivalent of a Layer 2 relay agent, without routing capabilities.


Note
LDRA is a device or interface on which LDRA functionality is configured.

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 DHCPv6 Relay—Lightweight DHCPv6 Relay Agent

  • You must understand DHCP and the functions of DHCP version 6 (DHCPv6) relay agents.

Restrictions for DHCPv6 Relay—Lightweight DHCPv6 Relay Agent

  • An interface or port cannot be configured as both client facing and server facing at the same time.

  • Access nodes implementing Lightweight DHCPv6 Relay Agent (LDRA) do not support IPv6 control or routing.

  • Unlike a DHCPv6 relay agent, an LDRA does not implement any IPv6 control functions (like Internet Control Message Protocol version 6 [ICMPv6] functions) nor does it have any routing capability in the node.

Information About DHCPv6 Relay—Lightweight DHCPv6 Relay Agent

Background

A variety of different link-layer network topologies exist for the aggregation of IPv6 nodes into one or more routers. In Layer 2 aggregation networks (IEEE 802.1D bridging or similar) that have many nodes on a single link, a DHCP version 6 (DHCPv6) server or DHCP relay agent normally does not recognize how a DHCP client is attached to a network. Lightweight DHCPv6 Relay Agent (LDRA) allows relay-agent information, including the Interface-ID option, to be inserted by the access node so that the information may be used by the DHCPv6 server for client identification.

Interoperability between DHCPv6 Relay Agents and LDRA

DHCP version 6 (DHCPv6) relay agents are used to forward DHCPv6 messages between a client and a server when the client and server are not on the same IPv6 link. A DHCPv6 relay agent also adds an interface identifier option in the upstream DHCPv6 message (from client to server) to identify the interface on which the client is connected. This information is used by the DHCPv6 relay agent while forwarding the downstream DHCPv6 message to the DHCPv6 client. The DHCPv6 relay agent is implemented alongside the routing functionality on the common node.

To maintain interoperability with existing DHCP relays and servers, Lightweight DHCPv6 Relay Agent (LDRA) implements the same message types (Relay-Forward and Relay-Reply) as a DHCPv6 relay agent.

LDRA allows relay-agent information to be inserted by an access node that performs a link-layer bridging (i.e., non-routing) function. The LDRA resides on the same IPv6 link as the client and a DHCPv6 relay agent or server.

LDRA for VLANs and Interfaces

You can configure LDRA on VLANs and interfaces. LDRA is not enabled by default. You must enable it on the VLAN or interface first.

In a typical deployment, a majority of the interfaces or ports on a device are client facing. In such a scenario, you can configure Lightweight DHCPv6 Relay Agent (LDRA) functionality on the VLAN. When you configure LDRA functionality on a VLAN, the functionality is configured on all the ports or interfaces within the VLAN. Instead of configuring LDRA functionality individually on the interfaces and ports within a VLAN, you can configure LDRA on the entire VLAN. As a result, all the ports or interfaces associated with the VLAN will be configured as client facing.


Note

The LDRA configuration on a VLAN has to be configured as trusted or untrusted.

You can also configure LDRA functionality on a specific interface or port. An interface or port can be configured as - client-facing trusted, client-facing untrusted, or server facing.


Note

An LDRA must implement a configuration setting for all client-facing interfaces, marking them as trusted or as untrusted.

By default, any interface that is configured as client facing will be configured as an untrusted interface. When a client-facing interface is deemed untrusted, LDRA will discard any message of type RELAY-FORWARD received from the client-facing interface.

How to Configure a Lightweight DHCPv6 Relay Agent

Configuring LDRA Functionality on a VLAN

SUMMARY STEPS

    1.    enable

    2.    configure terminal

    3.    ipv6 dhcp-ldra {enable | disable | remote-id remote-id}

    4.    vlan configuration vlan-number

    5.    ipv6 dhcp ldra attach-policy {client-facing-trusted | client-facing-untrusted}

    6.    exit

    7.    interface type number

    8.    switchport

    9.    switchport access vlan vlan-number

    10.    ipv6 dhcp-ldra attach-policy {client-facing-trusted | client-facing-untrusted | client-facing-disable | server-facing}

    11.    exit

    12.    interface type number

    13.    switchport

    14.    switchport access vlan vlan-number

    15.    ipv6 dhcp-ldra attach-policy {client-facing-trusted | client-facing-untrusted | client-facing-disable | server-facing}

    16.    end


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# configure terminal
     

    Enters global configuration mode.

     
    Step 3 ipv6 dhcp-ldra {enable | disable | remote-id remote-id}

    Example: 
    Device(config)# ipv6 dhcp-ldra enable
          		Enables LDRA functionality globally.

    • You need to enable LDRA functionality in global configuration mode before configuring it on an interface.

    • The ipv6 dhcp-ldra remote-id command is optional. By default, a system-generated remote ID is used; however if the command is configured, it overrides the system-generated remote ID.

     
    Step 4 vlan configuration vlan-number


    Example:
    Device(config)# vlan configuration 5
     

    Specifies a VLAN number and enters into VLAN configuration mode.

     
    Step 5 ipv6 dhcp ldra attach-policy {client-facing-trusted | client-facing-untrusted}

    Example: 
    Device (config-vlan-config)# ipv6 dhcp ldra attach-policy client-facing-trusted
     

    Enables LDRA functionality on a specified VLAN.

    Note   

    The client-facing-trusted keyword configures all the ports or interfaces associated with the VLAN as client facing, trusted ports. The client-facing-untrusted keyword configures all the ports or interfaces associated with the VLAN as client facing, untrusted ports.

     
    Step 6 exit


    Example: 
    Device (config-vlan-config)# exit
     

    Exits VLAN configuration mode and returns to global configuration mode.

     
    Step 7 interface type number


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

    Specifies an interface type and number, and enters interface configuration mode.

     
    Step 8 switchport


    Example:
    Device(config-if)# switchport
     

    Switches an interface that is in Layer 3 mode into Layer 2 mode for Layer 2 configuration.

     
    Step 9 switchport access vlan vlan-number


    Example:
    Device(config-if)# switchport access vlan  5
     

    Specifies that an interface operates in VLAN 5 instead of the default VLAN in the interface configuration mode.

     
    Step 10 ipv6 dhcp-ldra attach-policy {client-facing-trusted | client-facing-untrusted | client-facing-disable | server-facing}

    Example:
    Device(config-if)# ipv6 dhcp-ldra attach-policy client-facing-trusted
     

    Enables LDRA functionality on a specified interface or port.

    Note   

    The client-facing-trusted keyword configures the specified port or interface as a client facing, trusted port. The client-facing-disable keyword disables LDRA functionality on an interface or port. The server-facing keyword specifies an interface or port as server facing.

     
    Step 11 exit


    Example: 
    Device (config-if)# exit
     

    Exits interface configuration mode and returns to global configuration mode.

     
    Step 12 interface type number


    Example:
    Device(config)# interface ethernet 1/0
     

    Specifies an interface type and number, and enters interface configuration mode.

     
    Step 13 switchport


    Example:
    Device(config-if)# switchport
     

    Switches an interface that is in Layer 3 mode into Layer 2 mode for Layer 2 configuration.

     
    Step 14 switchport access vlan vlan-number


    Example:
    Device(config-if)# switchport access vlan  5
     

    Specifies that an interface operates in VLAN 5 instead of the default VLAN in the interface configuration mode.

     
    Step 15 ipv6 dhcp-ldra attach-policy {client-facing-trusted | client-facing-untrusted | client-facing-disable | server-facing}

    Example:
    Device(config-if)# ipv6 dhcp-ldra attach-policy server-facing
     

    Enables the LDRA functionality on the specified interface.

    Note   

    The client-facing-trusted keyword configures the specified port or interface as a client facing, trusted port. The client-facing-disable keyword disables LDRA functionality on an interface or port. The server-facing keyword specifies an interface or port as server facing.

     
    Step 16 end


    Example:
    Device(config-if)# end
     

    Exits VLAN configuration mode and returns to privileged EXEC mode.

     

    Configuring LDRA Functionality on an Interface

    SUMMARY STEPS

      1.    enable

      2.    configure terminal

      3.    ipv6 dhcp-ldra {enable | disable | remote-id remote-id}

      4.    interface type number

      5.    switchport

      6.    ipv6 dhcp ldra interface-id interface-id

      7.    end


    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# configure terminal
       

      Enters global configuration mode.

       
      Step 3 ipv6 dhcp-ldra {enable | disable | remote-id remote-id}


      Example: 
      Device(config)# ipv6 dhcp-ldra enable
       

      Enables LDRA functionality globally.

      • You need to enable LDRA functionality in global configuration mode before configuring it on an interface.

      • The ipv6 dhcp-ldra remote-id command is optional. By default, a system-generated remote ID is used. If the command is configured, it overrides the system-generated remote ID.

       
      Step 4 interface type number


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

      Specifies an interface type and number, and enters interface configuration mode.

       
      Step 5 switchport


      Example:
      Device(config-if)# switchport
       

      Switches an interface that is in Layer 3 mode into Layer 2 mode for Layer 2 configuration.

       
      Step 6ipv6 dhcp ldra interface-id interface-id


      Example: 
      Device(config-if)# ipv6 dhcp ldra interface-id 2
       

      (Optional) Configures LDRA interface ID on a port or an interface.

      • The ipv6 dhcp ldra interface-id command is optional. By default, a short name of the interface is used. For example, eth0/0 is used for Ethernet 0/0. If the command is configured, it overrides the default value.

       
      Step 7end


      Example: 
      Device(config-if)# end
       

      Exits interface configuration mode and returns to privileged EXEC mode.

       

      Verifying and Troubleshooting LDRA

      SUMMARY STEPS

        1.    show ipv6 dhcp-ldra

        2.    show ipv6 dhcp-ldra statistics

        3.    debug ipv6 dhcp-ldra all


      DETAILED STEPS
        Step 1   show ipv6 dhcp-ldra

        This command displays LDRA configuration details. The fields in the example given below are self-explanatory.



        Example:
        Device # show ipv6 dhcp-ldra

DHCPv6 LDRA is Enabled.
DHCPv6 LDRA policy: client-facing-disable
       Target: none
DHCPv6 LDRA policy: client-facing-trusted
       Target: vlan 5
DHCPv6 LDRA policy: client-facing-untrusted
       Target: none
DHCPv6 LDRA policy: server-facing
       Target: Gi1/0/7
        Step 2   show ipv6 dhcp-ldra statistics

        This command displays LDRA configuration statistics before and after initiating a DHCP session. The fields in the examples below are self-explanatory.



        Example:
        Device # show ipv6 dhcp-ldra statistics

           DHCPv6 LDRA client facing statistics.
 Messages received 0
 Messages sent 0
 Messages discarded 0

           DHCPv6 LDRA server facing statistics.
 Messages received 0
 Messages sent 0
 Messages discarded 0


        Device # show ipv6 dhcp-ldra statistics

           DHCPv6 LDRA client facing statistics.
 Messages received 2
 Messages sent 2
 Messages discarded 0
 Messages Received
 SOLICIT 1
 REQUEST 1
 Messages Sent
 RELAY-FORWARD 2
 									 DHCPv6 LDRA server facingstatistics.
 Messages received 2
 Messages sent 2
 Messages discarded 0
 Messages Received 
 RELAY-REPLY 2
 Messages Sent
 ADVERTISE 1
 REPLY 1
        Step 3   debug ipv6 dhcp-ldra all

        This command enables all LDRA debugging flows. The fields in the example below are self-explanatory.



        Example:
        Device# debug ipv6 dhcp-ldra all


05:44:10: DHCPv6 LDRA API: Entered ipv6_dhcp_ldra_post_processor.
05:44:10: DHCPv6 LDRA EVENT: [Gi1/0/3 Vlan 5] Received SOLICIT from 2001:DB8:1::1 to FF02::1:2.
05:44:10:   type SOLICIT(1), xid 8035955
05:44:10:   option ELAPSED-TIME(8), len 2
05:44:10:     elapsed-time 0
05:44:10:   option CLIENTID(1), len 10
05:44:10:     000300010015F906981B
05:44:10:   option ORO(6), len 4
05:44:10:     DNS-SERVERS,DOMAIN-LIST
05:44:10:   option IA-NA(3), len 12
05:44:10:     IAID 0x00040001, T1 0, T2 0
05:44:10: DHCPv6 LDRA API: Entered dhcpv6_ldra_client_facing_new_pak.
05:44:10: DHCPv6 LDRA EVENT: [Vlan 5] Sending RELAY-FORWARD from 2001:DB8:1::1 to FF02::1:2.
05:44:10:   type RELAY-FORWARD(12), hop 0
05:44:10:   link ::
05:44:10:   peer 2001:DB8:1::1
05:44:10:   option RELAY-MSG(9), len 48
05:44:10:     type SOLICIT(1), xid 8035955
05:44:10:     option ELAPSED-TIME(8), len 2
05:44:10:       elapsed-time 0
05:44:10:     option CLIENTID(1), len 10
05:44:10:       000300010015F906981B
05:44:10:     option ORO(6), len 4
05:44:10:       DNS-SERVERS,DOMAIN-LIST
05:44:10:     option IA-NA(3), len 12
05:44:10:       IAID 0x00040001, T1 0, T2 0
05:44:10:   option INTERFACE-ID(18), len 7
05:44:10:     0x4769312F302F33
05:44:10:   option REMOTEID(37), len 22
05:44:10:     0x00000009020013000005000A00030001588D09F89A00
05:44:11: DHCPv6 LDRA API: Entered ipv6_dhcp_ldra_post_processor.
05:44:11: DHCPv6 LDRA EVENT: [Gi1/0/3 Vlan 5] Received SOLICIT from 2001:DB8:1::1 to FF02::1:2.
05:44:11:   type SOLICIT(1), xid 8035955
05:44:11:   option ELAPSED-TIME(8), len 2
05:44:11:     elapsed-time 0
05:44:11:   option CLIENTID(1), len 10
05:44:11:     000300010015F906981B
05:44:11:   option ORO(6), len 4
05:44:11:     DNS-SERVERS,DOMAIN-LIST
05:44:11:   option IA-NA(3), len 12
05:44:11:     IAID 0x00040001, T1 0, T2 0
05:44:11: DHCPv6 LDRA API: Entered dhcpv6_ldra_client_facing_new_pak.
05:44:11: DHCPv6 LDRA EVENT: [Vlan 5] Sending RELAY-FORWARD from 2001:DB8:1::1 to FF02::1:2.
05:44:11:   type RELAY-FORWARD(12), hop 0
05:44:11:   link ::
05:44:11:   peer 2001:DB8:1::1
05:44:11:   option RELAY-MSG(9), len 48
05:44:11:     type SOLICIT(1), xid 8035955
05:44:11:     option ELAPSED-TIME(8), len 2
05:44:11:       elapsed-time 0
05:44:11:     option CLIENTID(1), len 10
05:44:11:       000300010015F906981B
05:44:11:     option ORO(6), len 4
05:44:11:       DNS-SERVERS,DOMAIN-LIST
05:44:11:     option IA-NA(3), len 12
05:44:11:       IAID 0x00040001, T1 0, T2 0
05:44:11:   option INTERFACE-ID(18), len 7
05:44:11:     0x4769312F302F33
05:44:11:   option REMOTEID(37), len 22
05:44:11:     0x00000009020013000005000A00030001588D09F89A00
05:44:13: DHCPv6 LDRA API: Entered ipv6_dhcp_ldra_post_processor.
05:44:13: DHCPv6 LDRA EVENT: [Gi1/0/3 Vlan 5] Received SOLICIT from 2001:DB8:1::1 to FF02::1:2.
05:44:13:   type SOLICIT(1), xid 8035955
05:44:13:   option ELAPSED-TIME(8), len 2
05:44:13:     elapsed-time 0
05:44:13:   option CLIENTID(1), len 10
05:44:13:     000300010015F906981B
05:44:13:   option ORO(6), len 4
05:44:13:     DNS-SERVERS,DOMAIN-LIST
05:44:13:   option IA-NA(3), len 12
05:44:13:     IAID 0x00040001, T1 0, T2 0
05:44:13: DHCPv6 LDRA API: Entered dhcpv6_ldra_client_facing_new_pak.
05:44:13: DHCPv6 LDRA EVENT: [Vlan 5] Sending RELAY-FORWARD from 2001:DB8:1::1 to FF02::1:2.
05:44:13:   type RELAY-FORWARD(12), hop 0
05:44:13:   link ::
05:44:13:   peer 2001:DB8:1::1
05:44:13:   option RELAY-MSG(9), len 48
05:44:13:     type SOLICIT(1), xid 8035955
05:44:13:     option ELAPSED-TIME(8), len 2
05:44:13:       elapsed-time 0
05:44:13:     option CLIENTID(1), len 10
05:44:13:       000300010015F906981B
05:44:13:     option ORO(6), len 4
05:44:13:       DNS-SERVERS,DOMAIN-LIST
05:44:13:     option IA-NA(3), len 12
05:44:13:       IAID 0x00040001, T1 0, T2 0
05:44:13:   option INTERFACE-ID(18), len 7
05:44:13:     0x4769312F302F33
05:44:13:   option REMOTEID(37), len 22
05:44:13:     0x00000009020013000005000A00030001588D09F89A00
05:44:17: DHCPv6 LDRA API: Entered ipv6_dhcp_ldra_post_processor.
05:44:17: DHCPv6 LDRA EVENT: [Gi1/0/3 Vlan 5] Received SOLICIT from 2001:DB8:1::1 to FF02::1:2.
05:44:17:   type SOLICIT(1), xid 8035955
05:44:17:   option ELAPSED-TIME(8), len 2
05:44:17:     elapsed-time 0
05:44:17:   option CLIENTID(1), len 10
05:44:17:     000300010015F906981B
05:44:17:   option ORO(6), len 4
05:44:17:     DNS-SERVERS,DOMAIN-LIST
05:44:17:   option IA-NA(3), len 12
05:44:17:     IAID 0x00040001, T1 0, T2 0
05:44:17: DHCPv6 LDRA API: Entered dhcpv6_ldra_client_facing_new_pak.
05:44:17: DHCPv6 LDRA EVENT: [Vlan 5] Sending RELAY-FORWARD from 2001:DB8:1::1 to FF02::1:2.
05:44:17:   type RELAY-FORWARD(12), hop 0
05:44:17:   link ::
05:44:17:   peer 2001:DB8:1::1
05:44:17:   option RELAY-MSG(9), len 48
05:44:17:     type SOLICIT(1), xid 8035955
05:44:17:     option ELAPSED-TIME(8), len 2
05:44:17:       elapsed-time 0
05:44:17:     option CLIENTID(1), len 10
05:44:17:       000300010015F906981B
05:44:17:     option ORO(6), len 4
05:44:17:       DNS-SERVERS,DOMAIN-LIST
05:44:17:     option IA-NA(3), len 12
05:44:17:       IAID 0x00040001, T1 0, T2 0
05:44:17:   option INTERFACE-ID(18), len 7
05:44:17:     0x4769312F302F33
05:44:17:   option REMOTEID(37), len 22
05:44:17:     0x00000009020013000005000A00030001588D09F89A00

        Configuration Examples for a Lightweight DHCPv6 Relay Agent

        Example: Configuring LDRA Functionality on a VLAN

        The following example shows how to configure Lightweight DHCPv6 Relay Agent (LDRA) on a VLAN numbered 5. 

        Device> enable
Device# configure terminal
Device(config)# ipv6 dhcp-ldra enable
Device(config)# vlan configuration 5
Device(config-vlan-config)# ipv6 dhcp ldra attach-policy client-facing-trusted
Device(config-vlan-config)# exit
Device(config)# interface ethernet 0/0
Device(config-if)# switchport
Device(config-if)# switchport access vlan 5
Device(config-if)# ipv6 dhcp-ldra attach-policy client-facing-trusted 
Device(config-if)# exit
Device(config)# interface ethernet 1/0
Device(config-if)# switchport
Device(config-if)# switchport access vlan 5
Device(config-if)# ipv6 dhcp-ldra attach-policy server-facing 
Device(config-if)# end

        Example: Configuring LDRA Functionality on an Interface

        In the following example, LDRA is configured on the interface ethernet 0/0:

        Device> enable
Device # configure terminal
Device(config)# ipv6 dhcp-ldra enable
Device(config)# interface ethernet 0/0
Device(config-if)# switchport
Device(config-if)# ipv6 dhcp-ldra interface-id 2
Device(config-if)# end

        Additional References for DHCPv6 Relay—Lightweight DHCPv6 Relay Agent

        Related Documents

        Related Topic

        Document Title

        Configuring the DHCPv6 Relay Agent

        IP Addressing: DHCP Configuration Guide

        Cisco IOS commands

        Cisco IOS Master Command List, All Releases

        DHCP commands

        Cisco IOS IP Addressing Services Command Reference

        DHCP conceptual information

        DHCP Overview module in the IP Addressing: DHCP Configuration Guide

        Standards and RFCs

        Standard/RFC

        Title

        RFC 6221

        Lightweight DHCPv6 Relay Agent

        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 Relay—Lightweight DHCPv6 Relay Agent

        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 Lightweight DHCPv6 Relay Agent

        Feature Name

        Releases

        Feature Information

        DHCPv6 Relay—Lightweight DHCPv6 Relay Agent

        15.2(1)SY

        The DHCPv6 Relay—Lightweight DHCPv6 Relay Agent feature allows relay agent information to be inserted by an access node that performs a link-layer bridging function.

        The following commands were introduced or modified: clear ipv6 dhcp-ldra statistics, debug ipv6 dhcp-ldra, ipv6 dhcp ldra attach-policy, ipv6 dhcp-ldra, ipv6 dhcp-ldra attach-policy, show ipv6 dhcp-ldra.

        Glossary

        Access Node —A device that combines many interfaces onto one link. An access node is not IP-aware in a data path.

        Client facing —An interface on an access node that carries traffic towards a DHCPv6 client.

        LDRA—Lightweight DHCPv6 Relay Agent. An interface or device on which LDRA functionality is configured (or that supports LDRA functionality.)

        LDRA function—A function on an access node that intercepts DHCP messages between clients and servers.

        Link—A communication facility or medium over which nodes can communicate at the link layer.

        Link-local address—An IP address having only local scope that can be used to reach neighboring nodes attached to the same link. Every interface has a link-local address, which is defined by the address prefix fe80::/10.

        Network-facing—An interface on an access node that carries traffic towards a DHCPv6 server.

        Relay Agent—A node that acts as an intermediary to deliver DHCP messages between clients and servers.