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RSIP is an attempt to correct some of the problems with using NAT (network address translation) servers. The major problem with NAT is that it disrupts the end-to-end transparency of the Internet. In a fully transparent environment, a host has an Internet-authorized and -registered IP address that is recognized throughout the global Internet.

In a NAT environment, internal addresses are hidden. A NAT server separates the address space of an internal network from the Internet. The internal network uses private IP addressing schemes. There is a specific set of private IP addresses that Internet routers do not forward for security reasons. These addresses are outlined under "NAT (Network Address Translation)." A NAT server translates between internal and external addressing schemes. It changes the net- work layer and sometimes the transport layer header of each packet that crosses the NAT router.

RSIP was still under development at the time of this writing. Additional information, including a list of Internet drafts and RFCs, is available at the Web site listed on the related entries page. It is being developed by the IETF Network Address Translators (nat) Working Group.

RFC 2956 (Overview of 1999 IAB Network Layer Workshop, October 2000) describes the "state of the network layer and its impact on continued growth and usage of the Internet. In particular, it discusses RSIP, NAT (Network Address Translation), firewalls, IPv6, addressing, and various routing issues. RFC 2775 (Internet Transparency, February 2000) discusses transparency issues on the Internet.