IPv6CP

IPv6CP, or IPv6 Control Protocol, is a PPP (Point-to-Point Protocol) Network Control Protocol used to configure and manage IPv6 on a PPP link. It provides the mechanism for negotiating IPv6 parameters between the two ends of a PPP connection, in the same way that IPCP handles IPv4.

IPv6CP operates within the PPP framework and follows the same configure/acknowledge/reject exchange pattern as other PPP NCPs. After the PPP link is established by LCP (Link Control Protocol), a host and its peer exchange Configure-Request, Configure-Reply, and Configure-Reject messages to establish IPv6 functionality on the link. During this process, IPv6CP negotiates basic IPv6 parameters such as whether IPv6 is enabled on the link and the assignment of IPv6 addresses. An IPv6-Address option may be used to convey the local or remote IPv6 address, and in some implementations additional options related to prefix information can be supported.

Once negotiation completes successfully, IPv6 traffic can be carried over the PPP link using the assigned IPv6 addresses. Address assignment may rely on stateless autoconfiguration, duplicate address detection, or other IPv6 mechanisms, depending on the implementation and network policies. DNS configuration is typically handled by separate mechanisms (for example, DHCPv6 or IPv6 router advertisements) and is not a core function of IPv6CP.

Security considerations for IPv6CP are primarily related to the underlying PPP link, including any PPP authentication such as CHAP. IPv6CP itself does not provide encryption or end-to-end security. IPv6CP is defined in RFC 2472 and remains a foundational component for IPv6 connectivity over PPP in various networking environments. See also PPP, LCP, IPCP, and RFC 2472.