On IPv4 networks, addresses can be assigned to interfaces in three ways: manually using static addresses, dynamically using DHCP, or automatically using APIPA. Administrators of small networks often configure IPv4 addresses manually, while midsize to large organizations usually use DHCP. Automatic address configuration using APIPA, however, is usually used only on very small networks such as a home or office LAN that connects to the Internet using a DSL router.
Address assignment on IPv6 networks is somewhat different. IPv6 addresses can be assigned to an interface by doing the following:
- Manually configuring one or more IPv6 addresses on the interface
- Stateful address autoconfiguration using a DHCPv6 server
- Stateless address autoconfiguration based on the receipt of Router Advertisement messages
- Both stateful and stateless address autoconfiguration
In addition, a link-local address is always automatically configured on an interface regardless of whether stateful or stateless address autoconfiguration is being used.
The main difference, however, between address assignment in IPv6 and in IPv4 is that the IPv6 protocol was designed to be autoconfiguring. This means that, in most cases, you will neither need to assign addresses manually nor deploy a DHCPv6 server; instead, you can use stateless address autoconfiguration for most of your network hosts. This means that, in contrast with physical interfaces (network adapters) on IPv4 hosts which are usually single-homed (have only a single address assigned), most physical interfaces on IPv6 hosts are multihomed (have multiple addresses assigned). Specifically, a physical IPv6 interface usually has at least two addresses:
- An automatically generated link-local address, which is used for traffic on the local link
- An additional unicast address (either a global address or a unique local address), which is used for traffic that needs to be routed beyond the local link
Mitch Tulloch is a nine-time recipient of the Microsoft Most Valuable Professional (MVP) award and a widely recognized expert on Windows administration, deployment and virtualization. For more information see http://www.mtit.com. This tip was excerpted from his latest book Training Guide: Installing and Configuring Windows Server 2012 from Microsoft Press.