The Dynamic Host Configuration Protocol version 6 (DHCPv6) is a

network protocol A communication protocol is a system of rules that allows two or more entities of a communications system to transmit information via any variation of a physical quantity. The protocol defines the rules, syntax, semantics, and synchronization of ...

for configuring

Internet Protocol version 6 Internet Protocol version 6 (IPv6) is the most recent version of the Internet Protocol (IP), the communication protocol, communications protocol that provides an identification and location system for computers on networks and routes traffic ...

(IPv6) hosts with

IP address An Internet Protocol address (IP address) is a numerical label such as that is assigned to a device connected to a computer network that uses the Internet Protocol for communication. IP addresses serve two main functions: network interface i ...

es, IP prefixes,

default route In computer networking, the default route is a configuration of the Internet Protocol (IP) that establishes a forwarding rule for packets when no specific address of a next-hop host is available from the routing table or other routing mechanism ...

, local segment MTU, and other configuration data required to operate in an IPv6 network. It is not just the IPv6 equivalent of the

Dynamic Host Configuration Protocol The Dynamic Host Configuration Protocol (DHCP) is a network protocol, network management protocol used on Internet Protocol (IP) networks for automatically assigning IP addresses and other communication parameters to devices connected to the netw ...

for

IPv4 Internet Protocol version 4 (IPv4) is the first version of the Internet Protocol (IP) as a standalone specification. It is one of the core protocols of standards-based internetworking methods in the Internet and other packet-switched networks. ...

. IPv6 hosts may automatically generate IP addresses internally using stateless address autoconfiguration (SLAAC), or they may be assigned configuration data with DHCPv6, or both. IPv6 hosts that use stateless autoconfiguration may need information other than what SLAAC provides on a given network. DHCPv6 can provide this information whether it is being used to assign IP addresses or not. DHCPv6 can provide host with the addresses of

Domain Name System The Domain Name System (DNS) is a hierarchical and distributed name service that provides a naming system for computers, services, and other resources on the Internet or other Internet Protocol (IP) networks. It associates various information ...

(DNS) servers, but they can also be provided through

Neighbor Discovery Protocol The Neighbor Discovery Protocol (NDP), or simply Neighbor Discovery (ND), is a protocol of the Internet protocol suite used with Internet Protocol Version 6 (IPv6). It operates at the internet layer of the Internet model, and is responsible for ...

, which is the mechanism for stateless autoconfiguration. Many IPv6 routers, such as routers for residential networks, must be configured automatically with no operator intervention. Such routers require not only an IPv6 address for use in communicating with upstream routers, but also an IPv6 prefix for use in configuring devices on the downstream side of the router. DHCPv6 prefix delegation provides a mechanism for configuring such routers.

Operation

Port numbers

Clients listen for DHCP messages on UDP port 546. Servers and relay agents listen for DHCP messages on UDP port 547.

Identifiers

DHCP unique identifier

The DHCP unique identifier (DUID) is used by a client to get an IP address from a DHCPv6 server. It has a 2-byte DUID type field, and a variable-length identifier field up to 128 bytes. Its actual length depends on its type. The server compares the DUID with its database and delivers configuration data (address, lease times, DNS servers, etc.) to the client. Four DUID types are identified: * Link-layer address plus time (DUID-LLT) * Vendor-assigned unique ID based on enterprise number (DUID-EN) * Link-layer address (DUID-LL) * UUID-based DUID (DUID-UUID)

RFC 6939: Client Link-Layer Address Option

Due to the fact that it is difficult to manage multiple identifiers in a dual-stack environment, and the fact that DUIDs are simply not optimal for some situations, RFC 6939 was released, giving a way to identify a host based on its

MAC address A MAC address (short for medium access control address or media access control address) is a unique identifier assigned to a network interface controller (NIC) for use as a network address in communications within a network segment. This use i ...

. It defines a way for a DHCPv6 relay to pass that information to a DHCPv6 server.

Example

In this example, without rapid-commit present, the server's link-local address is and the client's link-local address is . * Client sends a ''solicit'' from []:546 to multicast address []:547. * Server replies with an ''advertise'' from []:547 to []:546. * Client replies with a ''request'' from []:546 to []:547. * Server finishes with a ''reply'' from []:547 to []:546.

DHCPv6 Message types

This table lists the DHCPv6 message types.

IETF standards

* , "Dynamic Host Configuration Protocol for IPv6 (DHCPv6)" - Obsoletes RFC 3315, RFC 3633, RFC 3736, RFC 4242, RFC 7083, RFC 7283, RFC 7550. * , "Dynamic Host Configuration Protocol (DHCPv6) Options for Session Initiation Protocol (SIP) Servers" * , "DNS Configuration options for Dynamic Host Configuration Protocol for IPv6 (DHCPv6)" * , "The Dynamic Host Configuration Protocol for IPv6 (DHCPv6) Client Fully Qualified Domain Name (FQDN) Option" * , "DHCPv6 Leasequery" support * , "Lightweight DHCPv6 Relay Agent" (LDRA) - Updates RFC 3315, Errata * , "Definition of the UUID-Based DHCPv6 Unique Identifier (DUID-UUID)" * , "Client Link-Layer Address Option in DHCPv6" * , "DHCPv6 Active Leasequery"

References

External links

IANA DHCPv6 Parameters

comparison of DHCPv6 packages and implementations (Last updated: April, 2009)
IPv6 Ready: DHCPv6
list of IPv6 Phase II Certified DHCPv6 implementations (Last updated: December, 2012) {{IPv6 IPv6 Application layer protocols de:Dynamic Host Configuration Protocol#DHCPv6