Note the following IPv6 address assignment methods and their descriptions:
- Manual Assignment – this is where the administrator assigns the addresses in a manual configuration process, which is prone to errors. The other methods are used to limit this risk of misconfiguration.
- SLAAC – (Stateless Address Auto-Configuration) is a method of automated assignment where the client will send a router solicitation message to the ISP router, which will respond with a router advertisement. The client takes the /64 prefix ID and generates its /64 host address based upon EUI-64 format, and uses the source address of the router advertisement as its default gateway. It will also send out a check to other routers on the network to see if there are conflicts, but there are otherwise no methods of address tracking built-in.
- Stateless DHCPv6 – This is often used with SLAAC, because it affords the client with all of the features of DHCP (including DNS servers, domain name, and other vendor DHCP options) except for the address assignment, which is why it is called stateless. The client identifies its stateless behavior to the DHCP server by setting the other-config-flag setting in its query.
- Stateful DHCPv6 – This is similar to DHCPv4 in that the DHCPv6 server ultimately offers the client an IP address for auto-configuration, and includes all of the normal DHCP information like domain name etc. The client identifies its stateful behavior ot the DHCP server by setting the managed-config-flag in the route advertisement.
- DHCPv6-PD – (DHCP Prefix Delegation) – An extension to DHCPv6. In this method, a client requests information from a prefix delegation server, who thereby assigns one or multiple subnets to a PD client, where the client then assigns addresses from these networks to available interfaces. A client is usually a CPE device.
Stuck-in-Active: Journal of an IT-Network Administrator 