Huawei Technologies Co., Ltd Univ. of Auckland IPv6 deployment is delayed by the existence of millions of subscriber network address translators (NATs) that cannot be upgraded to support IPv6. This document specifies a mechanism for traversal of such NATs. It is based on an address mapping and on a mechanism whereby suitably upgraded hosts behind a NAT may obtain IPv6 connectivity via a stateless server, known as a SAMPLE server, operated by their Internet Service Provider. SAMPLE is an alternative to the Teredo protocol.