Auto-configuration

In IPv4, the only mechanism for auto-configuration is DHCPv4. This allows nodes to obtain basic network configuration:

      • a node address (e.g. 172.20.3.1)
      • a subnet mask (e.g. 255.255.0.0)
      • the default gateway (e.g. 172.20.0.1)
      • IPv4 addresses of DNS (e.g. 172.20.0.11, 172.20.0.12)

This is done via broadcast requests to a local DHCPv4 server or relay agent, and further broadcast responses from the DHCPv4 server, which are received by the requesting node. This is a very “noisy” process.

It is possible to reserve a particular IP address for a node with a specific MAC address. Otherwise, node addresses are assigned on a first-come, first-served basis.

There are a number of other items that can be configured via DHCPv4.

IPv6 on the other hand three mechanisms for auto-configuration. You can implement SLAAC alone, SLACC with stateless DHCPv6 or SLAAC with stateful DHCPv6. DHCPv6 by itself cannot completely provide a node’s network configuration (there is no way to provide a default gateway via DHCPv6 – this is normally obtained via ND router discovery or manual configuration).

      • StateLess Address AutoConfiguration (SLACC), via router advertisement messages
      • DHCPv6 for stateless configuration (only subnet wide items, like IPv6 addresses of DNS)
      • DHCPv6 for stateful configuration (stateless information plus an assigned node address).