Challenges for the Internet Routing Infrastructure Introduced by Changes in Address Semantics

Historically, the meaning of an IP address has been to identify an interface on a network device. Routing protocols were developed based on the assumption that a destination address had this semantic. Over time, routing decisions have been enhanced to determine paths on which packets could be forwarded according to additional information carried principally within the packet headers, and dependent on policy coded in, configured at, or signaled to the routers. Many proposals have been made to add semantics to IP packets by placing additional information into existing fields, by adding semantics to IP addresses, or by adding fields to the packets. The intent is always to facilitate routing decisions based on these additional semantics in order to provide differentiated paths to enable forwarding of different packet flows on paths that may be distinct from those derived by shortest path first or path vector routing. We call this approach "Semantic Networking". This document describes the challenges to the existing routing system that are introduced by Semantic Networking. It then summarizes the opportunities for research into new or modified routing and   forwarding approaches that make use of additional semantics. This document is presented as a study to support further research into clarifying and understanding the issues. It does not pass comment on the advisability or practicality of any of the proposals   and does not define any technical solutions.