NetDEF, Inc. Cisco Systems, Inc. Google Shenzhen University Tsinghua University This note specifies using packets' source addresses in route lookups as additional qualifier to be used in hop-by-hop routing decisions. This applies to IPv6 [RFC8200] in general with specific considerations for routing protocol left for separate documents. There is nothing precluding similar operation in IPv4, but this is not in scope of this document. Note that destination/source routing, source/destination routing, SADR, source-specific routing, source-sensitive routing, S/D routing and D/S routing are all used synonymously.