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IPv6 - Concepts

Reviewed on 19 February 2024


Dynamic Host Configuration Protocol Version 6 (DHCPv6) is a network management protocol for dynamically assigning IPv6 addresses and other configuration parameters to clients on IPv6 networks. It represents a complete redesign of the functionalities of “classic” v4 DHCP, and comes in three different options: SLAAC, Stateless, and Stateful.


Each DHCP client and server has a DHCP Unique Identifier (DUID). DHCPv6 servers use the DUID to identify clients when assigning IPv6 addresses and other configuration parameters. DUIDs are made up of a 2-octet DUID type field, and a variable-length identifier field of up to 128 bytes. Four types of DUID are identified in RFC 8415: _ Link-layer address (MAC address) plus time (DUID-LLT) _ Vendor-assigned unique ID based on enterprise number (DUID-EN) _ Link-layer address (MAC address) (DUID-LL) _ UUID-based DUID (DUID-UUID)

IP Address

An Internet Protocol address is a unique address that identifies a device on the internet or a local network. Generally, when we talk about IP addresses, we are referring to IPv4 addresses. However, due to the global shortage of IPv4 addresses, IPv6 addresses have also been in deployment since the mid-2000s.


Internet Protocol Version 4 is the standard protocol used for IP addresses and routes most internet traffic as of today. Each IPv4 address has 32 bits. Written in human-readable form, an IPv4 address is generally shown as four octets of numbers separated by periods, e.g.


Internet Protocol Version 6 is the most recent version of the IP protocol used for IP addresses. Each IPv6 address has 128 bits. Written in human-readable form, an IPv6 address can be shown as eight groups of four hexadecimal digits, each group representing 16 bits and separated by a colon, e.g. 2001:0DB8:0000:0003:0000:01FF:0000:002E. Alternatively, 2001:DB8::3:0:1FF:0:2E. Dedibox network is wholly IPv6 compatible. IPv6 can be used as the main IP of your server, and also as an IP failover using the principle of virtual MAC.

Neighbor Discovery Protocol

The Neighbour Discovery Protocol (NDP) allows devices to discover neighbors, routers, prefixes, and other services on a Layer 3 network. When a client first comes online, it sends a Router Solicitation message, and if a router exists on the network it replies with a Router Advertisement message. From this message, the client learns the default gateway (the address of the router) and the global network prefix.


Stateless Auto Address Configuration is the simplest way to assign IP addresses in an IPv6 network. Using the Neighbor Discovery Protocol, devices request the network prefix from the router, and then use this prefix and their own MAC address to create an IPv6 address.

Stateful DHCPv6

With stateful DHCPv6, it is the DHCPv6 server that chooses and assigns IPv6 addresses to clients, unlike with SLAAC or Stateless DHCPv6 where the client creates their own IPv6 address. Stateful DHCPv6 is so-called because the DHCPv6 server keeps track of the state of IPv6 addresses on the network.

Stateless DHCPv6

Stateless DHCPv6 involves the initial use of SLAAC by a client to create its own IPv6 address, followed by an extra DHCPv6 request to get extra details from the DHCPv6 server, such as DNS server or domain name information. Stateful DHCPv6 is so-called because no server or client is keeping track of the overall state of IPv6 addresses on the network.

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