What is 6over4 (IPv6 over IPv4 without explicit tunnels)?

6over4 is an Internet transition mechanism for migration of IPv4 to IPv6 and also a system that allows transmission of IPv6 packets over an IPv4 network. The configuration of the networks allows you to interconnect a number of smaller IPv6 networks over an IPv4-based network core which provides the ability to provide IPv6 service without the need to upgrade the switches in the core network. In this, BGP is required to be configured so that it can exchange all routes and data packets that are tunneled. Special relay servers are also in place that allows 6to4 networks to communicate with native IPv6 networks.

Most IPv6 networks use auto-configuration, which requires the last 64 bits of the address for the host. It does not facilitate interoperation between IPv4-only hosts and IPv6-only hosts. It is a transparent mechanism that is used as a transport layer between multiple IPv6 nodes. The advantage of this is that IPv6 has around 4.3 billion addresses. IPv6 networks are easier and cheaper to manage. In this, networks must be configured manually or with DHCP and have many overlays to handle internet growth in the future. IPv6 is also faster than IPv4.