Assessing the Impact of Carrier-Grade NAT on Network Applications
RFC 7021

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Independent Submission                                    C. Donley, Ed.
Request for Comments: 7021                                     CableLabs
Category: Informational                                        L. Howard
ISSN: 2070-1721                                        Time Warner Cable
                                                            V. Kuarsingh
                                                   Rogers Communications
                                                                 J. Berg
                                                               CableLabs
                                                                J. Doshi
                                                        Juniper Networks
                                                          September 2013

   Assessing the Impact of Carrier-Grade NAT on Network Applications

Abstract

   NAT444 is an IPv4 extension technology being considered by Service
   Providers as a means to continue offering IPv4 service to customers
   while transitioning to IPv6.  This technology adds an extra Carrier-
   Grade NAT (CGN) in the Service Provider network, often resulting in
   two NATs.  CableLabs, Time Warner Cable, and Rogers Communications
   independently tested the impacts of NAT444 on many popular Internet
   services using a variety of test scenarios, network topologies, and
   vendor equipment.  This document identifies areas where adding a
   second layer of NAT disrupts the communication channel for common
   Internet applications.  This document was updated to include the
   Dual-Stack Lite (DS-Lite) impacts also.

Status of This Memo

   This document is not an Internet Standards Track specification; it is
   published for informational purposes.

   This is a contribution to the RFC Series, independently of any other
   RFC stream.  The RFC Editor has chosen to publish this document at
   its discretion and makes no statement about its value for
   implementation or deployment.  Documents approved for publication by
   the RFC Editor are not a candidate for any level of Internet
   Standard; see Section 2 of RFC 5741.

   Information about the current status of this document, any errata,
   and how to provide feedback on it may be obtained at
   http://www.rfc-editor.org/info/rfc7021.

Donley, et al.                Informational                     [Page 1]
RFC 7021                     NAT444 Impacts               September 2013

Copyright Notice

   Copyright (c) 2013 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
   (http://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
   to this document.

Donley, et al.                Informational                     [Page 2]
RFC 7021                     NAT444 Impacts               September 2013

Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  4
   2.  Testing Scope  . . . . . . . . . . . . . . . . . . . . . . . .  5
     2.1.  Test Cases . . . . . . . . . . . . . . . . . . . . . . . .  5
       2.1.1.  Case 1: Single Client, Single Home Network, Single
               Service Provider . . . . . . . . . . . . . . . . . . .  5
       2.1.2.  Case 2: Two Clients, Single Home Network, Single
               Service Provider . . . . . . . . . . . . . . . . . . .  6
       2.1.3.  Case 3: Two Clients, Two Home Networks, Single
               Service Provider . . . . . . . . . . . . . . . . . . .  7
       2.1.4.  Case 4: Two Clients, Two Home Networks, Two
               Service Providers Cross ISP  . . . . . . . . . . . . .  8
     2.2.  General Test Environment . . . . . . . . . . . . . . . . .  8
     2.3.  Test Metrics . . . . . . . . . . . . . . . . . . . . . . . 10
     2.4.  Test Scenarios Executed  . . . . . . . . . . . . . . . . . 11
     2.5.  General Test Methodologies . . . . . . . . . . . . . . . . 11
   3.  Observed CGN Impacts . . . . . . . . . . . . . . . . . . . . . 12
     3.1.  Dropped Services . . . . . . . . . . . . . . . . . . . . . 13
     3.2.  Performance Impacted Services  . . . . . . . . . . . . . . 14
     3.3.  Improvements since 2010  . . . . . . . . . . . . . . . . . 15
     3.4.  Additional CGN Challenges  . . . . . . . . . . . . . . . . 16
   4.  2011 Summary of Results  . . . . . . . . . . . . . . . . . . . 17
     4.1.  NAT444 . . . . . . . . . . . . . . . . . . . . . . . . . . 17
     4.2.  DS-Lite  . . . . . . . . . . . . . . . . . . . . . . . . . 19
   5.  2010 Summary of Results  . . . . . . . . . . . . . . . . . . . 22
     5.1.  Case 1: Single Client, Single Home Network, Single
           Service Provider . . . . . . . . . . . . . . . . . . . . . 22
     5.2.  Case 2: Two Clients, Single Home Network, Single