Propagating Explicit Congestion Notification Across IP Tunnel Headers Separated by a Shim
draft-ietf-tsvwg-rfc6040update-shim-05

Document Type Active Internet-Draft (tsvwg WG)
Last updated 2017-11-12
Replaces draft-briscoe-tsvwg-rfc6040bis, draft-briscoe-tsvwg-rfc6040update-shim
Stream IETF
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Stream WG state WG Document (wg milestone: Jan 2018 - Submit 'Propagating ... )
Document shepherd David Black
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Transport Area Working Group                                  B. Briscoe
Internet-Draft                                                 CableLabs
Updates: 6040, 2661, 2784, 3931, 4380,                 November 12, 2017
         7450 (if approved)
Intended status: Standards Track
Expires: May 16, 2018

 Propagating Explicit Congestion Notification Across IP Tunnel Headers
                          Separated by a Shim
                 draft-ietf-tsvwg-rfc6040update-shim-05

Abstract

   RFC 6040 on "Tunnelling of Explicit Congestion Notification" made the
   rules for propagation of ECN consistent for all forms of IP in IP
   tunnel.  This specification updates RFC 6040 to clarify that its
   scope includes tunnels where two IP headers are separated by at least
   one shim header that is not sufficient on its own for wide area
   packet forwarding.  It surveys widely deployed IP tunnelling
   protocols separated by such shim header(s) and updates the
   specifications of those that do not mention ECN propagation (L2TPv2,
   L2TPv3, GRE, Teredo and AMT).  This specification also updates RFC
   6040 with configuration requirements needed to make any legacy tunnel
   ingress safe.

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 May 16, 2018.

Copyright Notice

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

Briscoe                   Expires May 16, 2018                  [Page 1]
Internet-Draft      ECN over IP-shim-(L2)-IP Tunnels       November 2017

   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
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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   3
   3.  Scope of RFC 6040 . . . . . . . . . . . . . . . . . . . . . .   3
     3.1.  Feasibility of ECN Propagation between Tunnel Headers . .   4
     3.2.  Desirability of ECN Propagation between Tunnel Headers  .   5
   4.  Making a non-ECN Tunnel Ingress Safe by Configuration . . . .   5
   5.  IP-in-IP Tunnels with Tightly Coupled Shim Headers  . . . . .   6
     5.1.  Specific Updates to Protocols under IETF Change Control .   9
       5.1.1.  L2TP (v2 and v3) ECN Extension  . . . . . . . . . . .   9
       5.1.2.  GRE . . . . . . . . . . . . . . . . . . . . . . . . .  12
       5.1.3.  Teredo  . . . . . . . . . . . . . . . . . . . . . . .  13
       5.1.4.  AMT . . . . . . . . . . . . . . . . . . . . . . . . .  14
   6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  16
   7.  Security Considerations . . . . . . . . . . . . . . . . . . .  16
   8.  Comments Solicited  . . . . . . . . . . . . . . . . . . . . .  16
   9.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .  16
   10. References  . . . . . . . . . . . . . . . . . . . . . . . . .  17
     10.1.  Normative References . . . . . . . . . . . . . . . . . .  17
     10.2.  Informative References . . . . . . . . . . . . . . . . .  18
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .  20

1.  Introduction

   RFC 6040 on "Tunnelling of Explicit Congestion Notification"
   [RFC6040] made the rules for propagation of Explicit Congestion
   Notification (ECN [RFC3168]) consistent for all forms of IP in IP
   tunnel.

   A common pattern for many tunnelling protocols is to encapsulate an
   inner IP header (v4 or v6) with shim header(s) then an outer IP
   header (v4 or v6).  Some of these shim headers are designed as
   generic encapsulations, so they do not necessarily directly
   encapsulate an inner IP header.  Instead they can encapsulate headers
   such as link-layer (L2) protocols that in turn often encapsulate IP.

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