BITAG Report on Large Scale Network Address Translation

The Internet is running out of IPv4 addresses. A successor address format, IPv6, has been developed to support as many devices as can conceivably be connected to the Internet for the foreseeable future but the IPv6 transition will take several years to be completed. IPv4 and IPv6 will thus need to co-exist until the demand for IPv4 services diminishes.

Network operators are employing a variety of techniques to extend the life of IPv4 addressing given the specter of a long term IPv6 transition. Large Scale Network Address Translation (also known as “Large Scale NAT” or “LSN”) is one such technique. LSN equipment allows a large number of IPv4-enabled end devices to share a single public IPv4 address. Network Address Translation (“NAT”) functionality has long existed in local/private networks to help network operators manage their network addresses using private address space but network operators now contemplate using it on a widespread basis.

BITAG undertook review of LSN because IP address sharing is a key tool for extending the life of IPv4 during the transition to IPv6. LSN is likely to affect many players in the Internet ecosystem: ISPs, end users, application providers, equipment vendors, content delivery networks, and third parties such as law enforcement agencies. BITAG’s review analyzes the LSN and provides an overview of how network operators plan to use it and how LSN could impact these other interest groups. BITAG believes that a broad understanding of LSN and its implications will: (1) help stakeholders to prepare for actions that minimize the impact on end users and applications; (2) inform policymakers and regulators of the motivations and trade-offs for the deployment of this technology; (3) accelerate the transition to IPv6; and (4) more generally help to reduce or preclude friction and/or conflict surrounding use of this technique among stakeholders, as some have argued that Large Scale NAT could be abused by parties for anti-competitive, discriminatory, or other non-technical purposes.