Factors Influencing the Freedom to Change Protocols
draft-thomson-protocol-freedom-00

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Network Working Group                                         M. Thomson
Internet-Draft                                                   Mozilla
Intended status: Standards Track                          March 13, 2017
Expires: September 14, 2017

          Factors Influencing the Freedom to Change Protocols
                   draft-thomson-protocol-freedom-00

Abstract

   The ability to change protocols depends on exercising that ability.
   Protocols that don't change can find that the mechanisms that support
   change become unusable.

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
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   This Internet-Draft will expire on September 14, 2017.

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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Implementations of Protocols are Imperfect  . . . . . . . . .   2
     2.1.  Good Protocol Design is Not Sufficient  . . . . . . . . .   3
     2.2.  Multi-Party Interactions and Middleboxes  . . . . . . . .   4
   3.  Protocol Freedom  . . . . . . . . . . . . . . . . . . . . . .   5
     3.1.  Use of Protocol Freedom . . . . . . . . . . . . . . . . .   5
     3.2.  Reliance on Protocol Freedom  . . . . . . . . . . . . . .   6
     3.3.  Unused Extension Points Become Unusable . . . . . . . . .   7
   4.  Defensive Design Principles for Protocol Freedom  . . . . . .   7
     4.1.  Grease  . . . . . . . . . . . . . . . . . . . . . . . . .   7
     4.2.  Cryptography  . . . . . . . . . . . . . . . . . . . . . .   8
     4.3.  Visibility  . . . . . . . . . . . . . . . . . . . . . . .   8
   5.  Security Considerations . . . . . . . . . . . . . . . . . . .   9
   6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   9
   7.  Informative References  . . . . . . . . . . . . . . . . . . .   9
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .  12

1.  Introduction

   A successful protocol [RFC5218] will change in ways that allow it to
   continue to fulfill the needs of its users.  New use cases,
   conditions and constraints on the deployment of a protocol can render
   a protocol that does not change obsolete.

   Usage patterns and requirements for a protocol shift over time.
   Protocols can react to these shifts in one of three ways: adjust
   usage patterns within the constraints of the protocol, extend the
   protocol, and replace the protocol.  These reactions are
   progressively more disruptive, but are also dictated by the nature of
   the change in requirements over longer periods.

   Experience with Internet scale protocol deployment shows that
   changing protocols is not uniformly successful.
   [I-D.iab-protocol-transitions] examines the problem more broadly.

   This document examines the specific conditions that determine whether
   protocol maintainers have the ability - the freedom - to design and
   deploy new or modified protocols.

2.  Implementations of Protocols are Imperfect

   A change to a protocol can be made extremely difficult to deploy if
   there are bugs in implementations with which the new deployment needs
   to interoperate.  Bugs in the handling of new codepoints or
   extensions can mean that instead of handling the mechanism as
   designed, endpoints react poorly.  This can manifest as abrupt

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