IPv6 over Ethernet (IPoEv6) access refers to the access mode in which users access a BRAS by sending Dynamic Host Configuration Protocol for IPv6 (DHCPv6) packets, Neighbor Discovery (ND) packets, or IPv6 packets. In IPoEv6 access mode, users can directly access the Internet using Web browsers, without having to install client dial-in software on their PCs.
An IPoE dual-stack user can have both an IPv4 address and an IPv6 address. The IPoE dual-stack access is the combination of the IPoE access and the IPoEv6 access. An IPoE dual-stack user obtains an IPv4 address through IPoEv4 and an IPv6 address through IPoEv6; however, during this process, the user is authenticated only once.
IPv6, also called IP Next Generation (IPng), is the second-generation standard protocol of network layer protocols. As a set of specifications defined by the Internet Engineering Task Force (IETF), IPv6 is the upgraded version of IPv4. The most obvious difference between IPv4 and IPv6 is that IPv4 addresses are of 32 bits whereas IPv6 addresses are of 128 bits.
IPv6 address autoconfiguration has two modes, stateful address autoconfiguration and stateless address autoconfiguration. IPv4 has only one address assignment mode, the DHCP mode.
In stateless address autoconfiguration mode, a user running ND sends a Router Solicitation (RS) message to a neighboring router. After receiving the RS message, the router assigns an IPv6 prefix to the user through a Router Advertisement (RA) message.
In stateful address autoconfiguration mode, a DHCPv6 client sends an Information-Request message containing the IPv6 address and information about the DNS server to the DHCPv6 server. After receiving the message, the DHCP server replies with the required configuration information according to the policy.
With the development of the Internet, the shortage of IPv4 address spaces becomes increasingly serious. IPv6 solves the problem of IP address exhaustion. With the development of the IPv6 Internet, users need to obtain IPv6 addresses for accessing network resources.