The forwarding of packets in today's networks has long evolved beyond ensuring mere reachability of the receiving endpoint. Instead, other 'purposes' of communication, e.g., ensuring quality of service of delivery, ensuring protection against path failures through utilizing more than one, and others, are realized by many extensions to the original reachability purpose of IP routing. Semantic Routing defines an approach to realizing such extended purposes beyond reachability by instead making routing and forwarding decisions based, not only on the destination IP address, but on other information carried in an IP packet. The intent is to facilitate enhanced routing decisions based on this information in order to provide differentiated forwarding paths for specific packet flows. Software Defined Networking (SDN) places control of network elements (including all or some of their forwarding decisions) within external software components called controllers and orchestrators. This approach differs from conventional approaches that solely rely upon distributed routing protocols for the delivery of advanced connectivity services. By doing so, SDN aims to enable network elements to be simplified while still performing forwarding function. This document examines the applicability of SDN techniques to Semantic Routing and provides considerations for the development of Semantic Routing solutions in the context of SDN.
Individual IETF Internet-Draft - May 2023