464XLAT/NAT64 Optimization

This document proposes possible solutions to avoid certain drawbacks of IP/ICMP Translation Algorithm (SIIT) when the destinations are already available with IPv6. When SIIT is used as a stateless NAT46 and IPv4-only devices or applications initiate traffic flows to dual- stack services (in the operator network or Internet), those flows will be translated back to IPv4 by a NAT64. Avoiding this dual- translation will significantly reduce the usage of the NAT64 and the relevant logging, which may be a high impact when traffic flows are towards CDNs, caches or similar resources. This is the case for 464XLAT and MAP-T.