Network Working Group C. Donley
Internet-Draft CableLabs
Intended status: Informational L. Howard
Expires: April 22, 2011 Time Warner Cable
V. Kuarsingh
Rogers Communications
A. Chandrasekaran
V. Ganti
University of Colorado
October 19, 2010
Assessing the Impact of NAT444 on Network Applications
draft-donley-nat444-impacts-00
Abstract
NAT444 is an IPv4 extension technology being considered by Service
Providers to continue offering IPv4 service to customers while
transitioning to IPv6. This technology adds an extra Large-Scale NAT
("LSN") in the Service Provider network, thereby 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.
Status of this Memo
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This Internet-Draft will expire on April 22, 2011.
Copyright Notice
Copyright (c) 2010 IETF Trust and the persons identified as the
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document authors. All rights reserved.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. NAT444 Findings . . . . . . . . . . . . . . . . . . . . . . . 3
2.1. NAT444 Additional Challenges . . . . . . . . . . . . . . . 3
3. Test Cases . . . . . . . . . . . . . . . . . . . . . . . . . . 4
3.1. Case1: Single Client, Single Home Network, Single
Service Provider . . . . . . . . . . . . . . . . . . . . . 4
3.2. Case2: Two Clients, Single Home Network, Single
Service Provider . . . . . . . . . . . . . . . . . . . . . 5
3.3. Case3: Two Clients, Two Home Networks, Single Service
Provider . . . . . . . . . . . . . . . . . . . . . . . . . 6
3.4. Case4: Two Clients, Two Home Networks, Two Service
Providers Cross ISP . . . . . . . . . . . . . . . . . . . 7
4. Summary of Results . . . . . . . . . . . . . . . . . . . . . . 7
4.1. Case1: Single Client, Single Home Network, Single
Service Provider . . . . . . . . . . . . . . . . . . . . . 8
4.2. Case2: Two Clients, Single Home Network, Single
Service Provider . . . . . . . . . . . . . . . . . . . . . 9
4.3. Case3: Two Clients, Two Home Networks, Single Service
Provider . . . . . . . . . . . . . . . . . . . . . . . . . 9
4.4. Case4: Two Clients, Two Home Networks, Two Service
Providers Cross ISP . . . . . . . . . . . . . . . . . . . 10
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 10
6. Security Considerations . . . . . . . . . . . . . . . . . . . 10
7. Informative References . . . . . . . . . . . . . . . . . . . . 10
Appendix A. Acknowledgements . . . . . . . . . . . . . . . . . . 11
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 11
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1. Introduction
Current projections suggest that IANA will exhaust its free pool of
IPv4 addresses in 2011. IPv6 is the solution to the IPv4 depletion
problem; however, the transition to IPv6 will not be completed prior
to IPv4 exhaustion. NAT444 [I-D.shirasaki-nat444] is one transition
mechanism that will allow Service Providers to multiplex customers
behind a single IPv4 address, which will allow many legacy devices
and applications some IPv4 connectivity without requiring a home
router upgrade. While NAT444 does provide basic IPv4 connectivity,
it breaks a number of advanced applications. This document describes
suboptimal behaviors of NAT444 in our test environments.
2. NAT444 Findings
Overall, NAT444 was able to provide IPv4 connectivity for many basic
operations conducted by consumers; however, there are several areas
of concern with respect to the nested NAT environments. In
particular, many advanced tasks (e.g. peer-to-peer seeding, video
streaming, some Internet gaming, and IPv6 transition technologies
such as 6to4 [RFC3056] and Teredo [RFC4380]) fail outright or are
subject to severe service degradation. We observed that performance
often differs from vendor to vendor and from test environment to test
environment, and the results are somewhat difficult to predict.
2.1. NAT444 Additional Challenges
There are other challenges that arise when using shared IPv4 address
space, as with NAT444. Some of these challenges include:
o Loss of geolocation information - Often, translation zones will
cross traditional geographic boundaries. Since the source
addresses of packets traversing an LSN are set to the external
address of the LSN, it is difficult for external entities to
associate IP/Port information to specific locations/areas.
o Lawful Intercept/Abuse Response - Due to the nature of NAT444
address sharing, it will be hard to determine the customer/
endpoint responsible for initiating a specific IPv4 flow based on
source IP address alone. Content providers, service providers,
and law enforcement agencies will need to use new mechanisms (e.g.
logging port/IP information, timestamps etc) to potentially
mitigate this new problem. This may impact the timely response to
various identification requests.
o Antispoofing - Multiplexing users behind a single IP address can
lead to situations where traffic from that address triggers
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antispoofing/DDoS protection mechanisms, resulting in
unintentional loss of connectivity for some users.
3. Test Cases
The test cases illustrated below are designed to simulate an average
home user experience for various combinations of clients behind a
single or multiple LSN devices.
3.1. Case1: Single Client, Single Home Network, Single Service Provider
^^^^^^^^
(Internet)
vvvvvvvv
|
|
+---------------+
| LSN |
+---------------+
|
+---------------+
| CMTS |
+---------------+
|
+---------------+
| CM |
+---------------+
|
+-------------------------+
| Home Router |
+-------------------------+
|
+---------------+
| Client |
+---------------+
This is a typical case for a client accessing content on the
Internet. For this case, we focused on basic web browsing, voice and
video chat, instant messaging, video streaming (using YouTube, Google
Videos , etc.), Torrent leeching and seeding, FTP, and gaming.
Applications used in this case generally worked better than other
topologies. However, Netflix streaming performance was generally
slow and erratic. Also, large FTP downloads experienced issues when
translation mappings timed out. Bittorrent seeding also failed
during some tests. Finally, when a feature on XBOX is used to
determine the Network Settings, it generates a warning that NAT
settings are not ideal and may slow down the experience when more
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than one client is connected. Gaming generally worked, but had
connectivity problems behind one specific LSN platform. Slingcatcher
video streaming failed.
3.2. Case2: Two Clients, Single Home Network, Single Service Provider
^^^^^^^^
(Internet)
vvvvvvvv
|
|
+---------------+
| LSN |
+---------------+
|
+---------------+
| CMTS |
+---------------+
|
+---------------+
| CM |
+---------------+
|
+-------------------------+
| Home Router |
+-------------------------+
| |
+---------------+ +---------------+
| Client | | Client |
+---------------+ +---------------+
This is similar to Case 1, except that two clients are behind the
same LSN and in the same home network. This test case was conducted
to observe any change in speed in basic web browsing and video
streaming. It is generally noted that the performance decreases in
bandwidth intensive applications. Torrent leeching was performed
from the two clients to a public server in the Internet. The
observed speed was considerably slower than with only one client
connected to the home network. Torrent seeding fails. Netflix video
streaming is also observed to be considerably choppy. When streaming
starts on one client, it does not start on the other, generating a
message saying that the Internet connection is too slow.
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3.3. Case3: Two Clients, Two Home Networks, Single Service Provider
^^^^^^^^
(Internet)
vvvvvvvv
|
|
+---------------+
| LSN |
+---------------+
|
+---------------+
| CMTS |
+---------------+
|
----------------------------------------
| |
+---------------+ +---------------+
| CM | | CM |
+---------------+ +---------------+
| |
+-------------------------+ +-------------------------+
| Home Router | | Home Router |
+-------------------------+ +-------------------------+
| |
+---------------+ +---------------+
| Client | | Client |
+---------------+ +---------------+
In this scenario, the two clients are under the same LSN but behind
two different gateways. This simulates connectivity between two
residential subscribers on the same ISP. We tested peer-to-peer
applications. utorrent leeching and limewire leeching passed, while
utorrent seeding and limewire seeding failed.
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3.4. Case4: Two Clients, Two Home Networks, Two Service Providers Cross
ISP
^^^^^^^^ ^^^^^^^^
( ISP A ) ( ISP B )
Vvvvvvvv vvvvvvvv
| |
+---------------+ +---------------+
| LSN | | LSN |
+---------------+ +---------------+
| |
+---------------+ +---------------+
| CMTS | | CMTS |
+---------------+ +---------------+
| |
+---------------+ +---------------+
| CM | | CM |
+---------------+ +---------------+
| |
+-------------------------+ +-------------------------+
| Home Router | | Home Router |
+-------------------------+ +-------------------------+
| |
+---------------+ +---------------+
| Client | | Client |
+---------------+ +---------------+
This test case is similar to Case 1 but with the addition of another
identical ISP. This topology allows us to test traffic between two
residential customers connected across the Internet. We focused on
client-to-client applications such as IM and peer-to-peer. Instant
messaging applications including Skype and Google Talk perform well.
Skype video and voice chat also performed well. However, FTP
transfers and peer-to-peer seeding failed.
4. Summary of Results
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4.1. Case1: Single Client, Single Home Network, Single Service Provider
+--------------+---------------+------------------------------------+
| Test Case | Results | Notes |
+--------------+---------------+------------------------------------+
| Web browsing | pass | |
| Email | pass | |
| FTP download | pass | performance degraded on very large |
| | | downloads |
| Bittorrent | pass | |
| leeching | | |
| Bittorrent | fail | |
| seeding | | |
| Video | pass | |
| streaming | | |
| Voice chat | pass | |
| Netflix | pass | |
| streaming | | |
| Instant | pass | |
| Messaging | | |
| Ping | pass | |
| Traceroute | pass | |
| Remote | pass | |
| desktop | | |
| VPN | pass | |
| Xbox live | pass | |
| Xbox online | pass | Blocked by some LSNs. |
| Xbox network | fail | Your NAT type is moderate. For |
| test | | best online experience you need an |
| | | open NAT configuration. You |
| | | should enable UPnP on the router. |
| Nintendo Wii | pass behind | |
| | one LSN, fail | |
| | behind | |
| | another | |
| Playstation | pass | |
| 3 | | |
| Team | fail | pass behind one LSN, but |
| Fortress 2 | | performance degraded |
| Starcraft II | pass | |
| World of | pass | |
| Warcraft | | |
| Call of Duty | pass | performance degraded behind one |
| | | LSN |
| Slingcatcher | fail | |
| Netflix | fail | pass behind one LSN |
| Party (Xbox) | | |
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| Hulu | pass | performance degraded behind one |
| | | LSN |
| AIM File | pass | performance degraded |
| Tranfer | | |
| Webcam | fail | |
| 6to4 | fail | |
| Teredo | fail | |
+--------------+---------------+------------------------------------+
Case1
4.2. Case2: Two Clients, Single Home Network, Single Service Provider
+-----------------+---------+---------------------------------------+
| Test Case | Results | Notes |
+-----------------+---------+---------------------------------------+
| Bittorrent | pass | |
| leeching | | |
| Bittorrent | fail | |
| seeding | | |
| Video streaming | fail | |
| Voice chat | pass | |
| Netflix | pass | performance severely impacted, |
| streaming | | eventually failed |
| IM | pass | |
| Limewire | pass | |
| leeching | | |
| Limewire | fail | |
| seeding | | |
+-----------------+---------+---------------------------------------+
Case2
4.3. Case3: Two Clients, Two Home Networks, Single Service Provider
+-------------------+---------+-------+
| Test Case | Results | Notes |
+-------------------+---------+-------+
| Limewire leeching | pass | |
| Limewire seeding | fail | |
| Utorrent leeching | pass | |
| Utorrent seeding | fail | |
+-------------------+---------+-------+
Case3
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4.4. Case4: Two Clients, Two Home Networks, Two Service Providers Cross
ISP
+------------------+---------+-------+
| Test Case | Results | Notes |
+------------------+---------+-------+
| Skype voice call | pass | |
| IM | pass | |
| FTP | fail | |
| Facebook chat | pass | |
| Skype video | pass | |
+------------------+---------+-------+
Case4
5. IANA Considerations
This document has no IANA considerations.
6. Security Considerations
Security considerations are described in [I-D.shirasaki-nat444].
7. Informative References
[I-D.nishitani-cgn]
Yamagata, I., Miyakawa, S., Nakagawa, A., and H. Ashida,
"Common requirements for IP address sharing schemes",
draft-nishitani-cgn-05 (work in progress), July 2010.
[I-D.shirasaki-nat444]
Yamagata, I., Shirasaki, Y., Nakagawa, A., Yamaguchi, J.,
and H. Ashida, "NAT444", draft-shirasaki-nat444-02 (work
in progress), July 2010.
[RFC3056] Carpenter, B. and K. Moore, "Connection of IPv6 Domains
via IPv4 Clouds", RFC 3056, February 2001.
[RFC4380] Huitema, C., "Teredo: Tunneling IPv6 over UDP through
Network Address Translations (NATs)", RFC 4380,
February 2006.
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Appendix A. Acknowledgements
Thanks to the following people (in alphabetical order) for their
guidance and feedback:
Paul Eldridge
John Berg
Lane Johnson
Authors' Addresses
Chris Donley
CableLabs
858 Coal Creek Circle
Louisville, CO 80027
USA
Email: c.donley@cablelabs.com
Lee Howard
Time Warner Cable
13241 Woodland Park Rd
Herndon, VA 20171
USA
Email: william.howard@twcable.com
Victor Kuarsingh
Rogers Communications
8200 Dixie Road
Brampton, ON L6T 0C1
Canada
Email: victor.kuarsingh@rci.rogers.com
Abishek Chandrasekaran
University of Colorado
Email: abishek.chandrasekaran@colorado.edu
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Vivek Ganti
University of Colorado
Email: vivek.ganti@colorado.edu
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