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