Security Measures to couple mixed IPv4/IPv6 Networks over a pure IPv6 Infrastructure by making Use of NAT-PT

The next generation of the Internet Protocol (IPv6) was developed to improve the within the Internet widespread deployed Internet Protocol (IPv4). Among other things it enlarges the available addressing space and improves security. Due to lack of unique IPv4 address space one strategy to couple existing IPv4 networks that uses private IPv4 addresses is to define a unique IPv6 network on top of the coupled IPv4 networks. At the border routers the use of NAT-PT (Network Address Translation - Protocol Translation) ensures that the IPv4 hosts have assigned virtual unique IPv6-addresses. IPv6 is used between the border routers. This ensures a smooth migration from a pure IPv4 to a pure IPv6 environment. The scope of this paper is to present a European test installation where NAT-PT is used to couple national networks over an IPv6 backbone. The description focuses on one national test installation with respect to security. The security impact on each communication layer will be discussed to ensure an acceptable level of security within the NAT-PT test installation.