Path signals
draft-hardie-path-signals-02

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Network Working Group                                     T. Hardie, Ed.
Internet-Draft                                         November 30, 2017
Intended status: Informational
Expires: June 3, 2018

                              Path signals
                      draft-hardie-path-signals-02

Abstract

   TCP's state mechanics uses a series of well-known messages that are
   exchanged in the clear.  Because these are visible to network
   elements on the path between the two nodes setting up the transport
   connection, they are often used as signals by those network elements.
   In transports that do not exchange these messages in the clear, on-
   path network elements lack those signals.  This document discusses
   the nature of the signals as they are seen by on-path elements and
   reflects on best practices for transports which encrypt their state
   mechanics.

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
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   This Internet-Draft will expire on June 3, 2018.

Copyright Notice

   Copyright (c) 2017 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (https://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect

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   to this document.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   3.  Signals Type Inferred . . . . . . . . . . . . . . . . . . . .   3
     3.1.  Session establishment . . . . . . . . . . . . . . . . . .   3
       3.1.1.  Session identity  . . . . . . . . . . . . . . . . . .   3
       3.1.2.  Routability and Consent . . . . . . . . . . . . . . .   4
       3.1.3.  Resource Requirements . . . . . . . . . . . . . . . .   4
     3.2.  Network Measurement . . . . . . . . . . . . . . . . . . .   4
       3.2.1.  Path Latency  . . . . . . . . . . . . . . . . . . . .   4
       3.2.2.  Path reliability and consistency  . . . . . . . . . .   4
   4.  Options . . . . . . . . . . . . . . . . . . . . . . . . . . .   4
     4.1.  Do not restore these signals  . . . . . . . . . . . . . .   5
     4.2.  Replace these with network layer signals  . . . . . . . .   5
     4.3.  Replace these with per-transport signals  . . . . . . . .   5
     4.4.  Create a set of signals common to multiple transports . .   5
   5.  Recommendation  . . . . . . . . . . . . . . . . . . . . . . .   6
   6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   6
   7.  Security Considerations . . . . . . . . . . . . . . . . . . .   6
   8.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   7
   9.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   7
     9.1.  Normative References  . . . . . . . . . . . . . . . . . .   7
     9.2.  Informative References  . . . . . . . . . . . . . . . . .   7
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .   8

1.  Terminology

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in RFC 2119 [RFC2119].

2.  Introduction

   TCP [RFC0793] uses handshake messages to establish, maintain, and
   close connections.  While these are primarily intended to create
   state between two communicating nodes, these handshake messages are
   visible to network elements along the path between them.  It has been
   common over time for certain network elements to treat the exchanged
   messages as signals which related to their own functions.

   A firewall may, for example, create a rule that allows traffic from a
   specific host and port to enter its network when the connection was

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