Deploying IPv4-only Connectivity across Local IPv6-only Access Networks

This document specifies a new mechanism called D4across6, which stands for Deploying IPv4-only Connectivity across Local IPv6-only Access Networks. This protocol could be used to ease the process of transition to IPv6 protocol, particularly in the ISPs' access networks. This protocol allows legacy IPv4-only devices to communicate with IPv4-only content providers over an IPv6-only infrastructure. The main part is an application level tunnelling protocol that allows IPv6-only ISPs to provide IPv4 connectivity in addition to IPv6 connectivity across IPv6-only access networks. It carries IPv4 packets and routing information of the IPv4 protocol over an IPv6-only network infrastructure. The features of the proposed protocol are: offers IPv4 connectivity across IPv6-only access networks, stateless operation, cost-effective solution, and requires simple and automatic configuration at customers' hosts. D4across6 requires installing an application and a pseudo network driver at the IPv4-only hosts in order to allow them to communicate with IPv4-only content providers. The configured IPv4-only hosts will be able to auto-detect the ISP available connectivity in the following precedence: native IPv6, IPv4-in-IPv6, or no IPv4 connectivity. The protocol does not require replacing or upgrading customer edges. Thus, a minimal cost is expected in providing IPv4-only connectivity after successfully deploying of IPv6 service to subscribers. The simulation analysis showed that the performance metrics of D4across6 is pretty near to those of native IPv6 and IPv4 protocols. Additionally, the performance of D4across6 is better than that of all (A+P), DS-Lite and 4rd protocols.