2. Motivation

2. Motivation

Information about the assignment procedures for the port registry has existed in three locations: the forms for requesting port number assignments on the IANA web site [SYSFORM] [USRFORM], an introductory text section in the file listing the port number assignments themselves (known as the port numbers registry) [PORTREG], and two brief sections of the IANA Allocation Guidelines [RFC2780].

Similarly, the procedures surrounding service names have been historically unclear. Service names were originally created as mnemonic identifiers for port numbers without a well-defined syntax, apart from the 14-character limit mentioned on the IANA website [SYSFORM] [USRFORM]. Even that length limit has not been consistently applied, and some assigned service names are 15 characters long. When service identification via DNS SRV Resource Records (RRs) was introduced [RFC2782], it became useful to start assigning service names alone, and because IANA had no procedure for assigning a service name without an associated port number, this led to the creation of an informal temporary service name registry outside of the control of IANA, which now contains roughly 500 service names [SRVREG].

This document aggregates all this scattered information into a single reference that aligns and clearly defines the management procedures for both service names and port numbers. It gives more detailed guidance to prospective requesters of service names and ports than the existing documentation, and it streamlines the IANA procedures for the management of the registry, so that requests can be completed in a timely manner.

This document defines rules for assignment of service names without associated port numbers, for such usages as DNS SRV records [RFC2782], which was not possible under the previous IANA procedures. The document also merges service name assignments from the non-IANA ad hoc registry [SRVREG] and from the IANA Protocol and Service Names registry [PROTSERVREG] into the IANA Service Name and Transport Protocol Port Number registry [PORTREG], which from here on is the single authoritative registry for service names and port numbers.

An additional purpose of this document is to describe the principles that guide the IETF and IANA in their role as the long-term joint stewards of the service name and port number registry. TCP and UDP have had remarkable success over the last decades. Thousands of applications and application-level protocols have service names and port numbers assigned for their use, and there is every reason to believe that this trend will continue into the future. It is hence extremely important that management of the registry follow principles that ensure its long-term usefulness as a shared resource. Section 7 discusses these principles in detail.