Deterministic Address Mapping to Reduce Logging in Carrier-Grade NAT Deployments

In some instances, Service Providers (SPs) have a legal logging requirement to be able to map a subscriber's inside address with the address used on the public Internet (e.g., for abuse response). Unfortunately, many logging solutions for Carrier-Grade NATs (CGNs) require active logging of dynamic translations. CGN port assignments are often per connection, but they could optionally use port ranges. Research indicates that per-connection logging is not scalable in many residential broadband services. This document suggests a way to manage CGN translations in such a way as to significantly reduce the amount of logging required while providing traceability for abuse response. IPv6 is, of course, the preferred solution. While deployment is in progress, SPs are forced by business imperatives to maintain support for IPv4. This note addresses the IPv4 part of the network when a CGN solution is in use. Status of This Memo This document is not an Internet Standards Track specification; it is published for informational purposes. This is a contribution to the RFC Series, independently of any other RFC stream. The RFC Editor has chosen to publish this document at its discretion and makes no statement about its value for implementation or deployment. Documents approved for publication by the RFC Editor are not a candidate for any level of Internet Standard; see Section 2 of RFC 5741. Information about the current status of this document, any errata, and how to provide feedback on it may be obtained at in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document.