Network Address Translation (NAT) and Realm Specific IP (RSIP) were proposed to extend the lifetime of IPv4 architecture. However NAT and RSIP do not have the ability to communicate with multi-layer private networks. This paper proposes an enhanced framework of multi-layer Realm-Specific IP (MRSIP) that not only inherits all the benefit of RSIP but also provides both end-to-end transparent-access capabilities and cascade private network connectivity. The MRSIP framework we propose includes the concept of cascade private network architecture, inter-private network accessing capabilities, and tunnel optimization. In addition, we provide a mechanism to avoid the private address collision problem.