3. Problem Statement and Considerations

When a stateless IPv4/IPv6 translator receives an ICMPv6 message [RFC4443] (for example, "Packet Too Big") sourced from a non-IPv4-translatable IPv6 address and bound for an IPv4-translatable IPv6 address, the translator needs to pick a source address with which to generate an ICMP message. For the reasons discussed below, this choice is problematic.