When experimenting with or extending protocols@ it is often necessary to use some sort of protocol number or constant in order to actually test or experiment with the new function@ even when testing in a closed environment. This document reserves some ranges of numbers for experimentation purposes in specific protocols where the need to support experimentation has been identified@ and it describes the numbers that have already been reserved by other documents.
RFC 4727-2006 history
2006RFC 4727-2006 Experimental Values in IPv4@ IPv6@ ICMPv4@ ICMPv6@ UDP@ and TCP Headers