This document analyzes a set of solution candidates which have been proposed to mitigate some of the issues encountered when address sharing is used. In particular, this document focuses on means to reveal a host identifier when a Carrier Grade NAT (CGN) or application proxies are involved in the path. This host identifier must be unique to each host under the same shared IP address. The ultimate goal is to assess the viability of proposed solutions and hopefully to make a recommendation on the more suitable solution(s).