1. Introduction

This white paper presents an overview of the Simple Internet Protocol plus (SIPP) which is one of the candidates being considered in the Internet Engineering Task Force (IETF) for the next version of the Internet Protocol (the current version is usually referred to as IPv4). This white paper is not intended to be a detailed presentation of all of the features and motivation for SIPP, but is intended to give the reader an overview of the proposal. It is also not intended that this be an implementation specification, but given the simplicity of the central core of SIPP, an implementor familiar with IPv4 could probably construct a basic working SIPP implementation from reading this overview.

SIPP is a new version of IP which is designed to be an evolutionary step from IPv4. It is a natural increment to IPv4. It can be installed as a normal software upgrade in internet devices and is interoperable with the current IPv4. Its deployment strategy was designed to not have any "flag" days. SIPP is designed to run well on high performance networks (e.g., ATM) and at the same time is still efficient for low bandwidth networks (e.g., wireless). In addition, it provides a platform for new internet functionality that will be required in the near future.

This white paper describes the work of IETF SIPP working group. Several individuals deserve specific recognition. These include Steve Deering, Paul Francis, Dave Crocker, Bob Gilligan, Bill

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RFC 1710 SIPP IPng White Paper October 1994

Simpson, Ran Atkinson, Bill Fink, Erik Nordmark, Christian Huitema, Sue Thompson, and Ramesh Govindan.

2. Key Issues for the Next Generation of IP

There are several key issues that should be used in the evaluation of any next generation internet protocol. Some are very straightforward. For example the new protocol must be able to support large global internetworks. Others are less obvious. There must be a clear way to transition the current installed base of IP systems. It doesn't matter how good a new protocol is if there isn't a practical way to transition the current operational systems running IPv4 to the new protocol.

2.1 Growth

Growth is the basic issue which caused there to be a need for a next generation IP. If anything is to be learned from our experience with IPv4 it is that the addressing and routing must be capable of handling reasonable scenarios of future growth. It is important that we have an understanding of the past growth and where the future growth will come from.

Currently IPv4 serves what could be called the computer market. The computer market has been the driver of the growth of the Internet. It comprises the current Internet and countless other smaller internets which are not connected to the Internet. Its focus is to connect computers together in the large business, government, and university education markets. This market has been growing at an exponential rate. One measure of this is that the number of networks in current Internet (23,494 as of 1/28/94) is doubling approximately every 12 months. The computers which are used at the endpoints of internet communications range from PC's to Supercomputers. Most are attached to Local Area Networks (LANs) and the vast majority are not mobile.

The next phase of growth will probably not be driven by the computer market. While the computer market will continue to grow at significant rates due to expansion into other areas such as schools (elementary through high school) and small businesses, it is doubtful it will continue to grow at an exponential rate. What is likely to happen is that other kinds of markets will develop. These markets will fall into several areas. They all have the characteristic that they are extremely large. They also bring with them a new set of requirements which were not as evident in the early stages of IPv4 deployment. The new markets are also likely to happen in parallel with other. It may turn out that we will look back on the last ten years of Internet growth as the time when the Internet was small and