IPv6 OSPF is based on IPv4 OSPF and has many similar concepts and controls. The primary difference between IPv6 OSPF and IPv4 OSPF is that for IPv6 OSPF, IP addresses are not used to communicate topology information. For example, in IPv4 OSPF, an interface is referred to by its IPv4 home address, but in IPv6 OSPF an interface is not referred to by any of its IPv6 home addresses. Instead, it is referred to by an integer interface ID. Similarly, IPv6 OSPF router IDs are not IPv6 home addresses; they are 32-bit integers written in IPv4-style dotted decimal notation. Area IDs in IPv6 OSPF are also 32-bit integers written in IPv4-style dotted decimal notation.