3.1.b Identify implement and troubleshoot IPv6 addressing and subnetting

3.1.b [viii] Stateful, stateless DHCPv6

DHCPv6 enables DHCP servers to pass configuration parameters, such as IPv6 network addresses, to IPv6 nodes. It offers the capability of automatic allocation of reusable network addresses and additional configuration flexibility. This protocol is a stateful counterpart to “IPv6 Stateless Address Autoconfiguration” (RFC 2462), and can be used separately, or in addition to the stateless auto-configuration to obtain configuration parameters.

Stateless DHCPv6 is a combination of “stateless Address Autoconfiguration” and DHCPv6. When using stateless-DHCPv6, a device will use Stateless Address Auto-Configuration (SLAAC) to assign one or more IPv6 addresses to an interface, while it utilizes DHCPv6 to receive “additional parameters” which may not be available through SLAAC. For example, additional parameters could include information such as DNS or NTP server addresses, and are provided in a stateless manner by DHCPv6. Using stateless DHCPv6 means that the DHCPv6 server does not need to keep track of any state of assigned IPv6 addresses, and there is no need for state refreshment as result. On network media supporting a large number of hosts associated to a single DHCPv6 server, this could mean a significant reduction in DHCPv6 messages due to the reduced need for address state refreshments. From Cisco IOS 12.4( 15) T onwards the client can also receive timing information, in addition to the “additional parameters” through DHCPv6. This timing information provides an indication to a host when it should refresh its DHCPv6 configuration data.

Adam, Paul (2014-07-12). All-in-One CCIE V5 Written Exam Guide (Kindle Locations 2396-2403).  . Kindle Edition.