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Versions: 00 01 02 03 04 RFC 6948

Network Working Group                                         A. Keranen
Internet-Draft                                                  J. Arkko
Intended status: Informational                                  Ericsson
Expires: January 5, 2012                                    July 4, 2011


     Some Measurements on World IPv6 Day from End-User Perspective
                 draft-keranen-ipv6day-measurements-00

Abstract

   During the World IPv6 Day on June 8th, 2011, several key content
   providers enabled their networks to offer both IPv4 and IPv6 service.
   Hundreds of organizations participated in this effort, and in the
   months and weeks leading up to the event worked hard on preparing
   their networks to support this event.  The event was largely
   unnoticed by the general public, which is a good thing as no major
   problems were detected.  For the Internet, however, there was a major
   change on such a small timescale.  This memo discusses measurements
   that the authors made from the perspective of an end-user with well-
   working IPv4 and IPv6 connectivity.  Our measurements include the
   number of most popular networks providing AAAA records for their
   service as well as delay and connection failure probabilities.

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
   Task Force (IETF).  Note that other groups may also distribute
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   Drafts is at http://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid for a maximum of six months
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   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on January 5, 2012.

Copyright Notice

   Copyright (c) 2011 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



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   (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
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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . . . 3
   2.  Motivation and Goals  . . . . . . . . . . . . . . . . . . . . . 3
   3.  Measurement Methodology . . . . . . . . . . . . . . . . . . . . 4
   4.  Measurement Results . . . . . . . . . . . . . . . . . . . . . . 5
     4.1.  DNS Measurements  . . . . . . . . . . . . . . . . . . . . . 5
     4.2.  Delay and Failure Measurements  . . . . . . . . . . . . . . 6
   5.  Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . 6
   6.  Security Considerations . . . . . . . . . . . . . . . . . . . . 6
   7.  IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 7
   8.  Informative References  . . . . . . . . . . . . . . . . . . . . 7
   Appendix A.  Acknowledgments  . . . . . . . . . . . . . . . . . . . 7
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . . . 7




























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1.  Introduction

   Many large content providers participated in World IPv6 Day on June
   8, 2011.  On that day, IPv6 [RFC2460] was enabled by default for 24
   hours on numerous networks and sites that previously supported only
   IPv4.  The aim was to identify any remaining issues with widespread
   IPv6 usage in these networks.  Most of the potential problems
   associated with using IPv6 are, after all, of a practical nature,
   such as: ensuring that the necessary components have IPv6 turned on;
   that configurations are correct; and that any implementation bugs
   have been removed.

   Some content providers have been reluctant to enable IPv6.  The
   reasons for this include delays for applications attempting to
   connect over broken IPv6 links before falling back to IPv4, and
   unreliable IPv6 connectivity.  Bad IPv6 routing has been behind many
   of the problems.  Among the causes are broken 6to4 tunneling protocol
   connectivity, experimental IPv6 setups that are untested and
   unmonitored, and configuration problems with firewalls.  The
   situation is improving as more users and operators put IPv6 to use
   and fix the problems that emerge.

   World IPv6 Day event was largely unnoticed by the general public,
   which is a good thing as no major problems were detected.  For the
   Internet, however, there was a major change on such a small
   timescale.  This memo discusses measurements that the authors made
   from the perspective of an end-user with well-working IPv4 and IPv6
   connectivity.  Our measurements include the number of most popular
   networks providing AAAA records for their service as well as delay
   and connection failure probabilities.

   The rest of this memo is structured as follows.  Section 2 discusses
   the goals of our measurements, Section 3 describes our measurement
   methodology, Section 4 gives our preliminary results, and Section 5
   makes some conclusions.


2.  Motivation and Goals

   Practical IPv6 deployment plans benefit from accurate information
   about the extent to which IPv6 can be used for communication, and how
   its characteristics differ from those of IPv4.  For instance,
   operators planning to deploy dual stack networking may wish to
   understand what fraction of their traffic would move to IPv6.  This
   information is useful for estimating sufficient capacity to deal with
   the IPv6 traffic and impacts to the operator's IPv4 infrastructure or
   carrier-grade NAT devices as their traffic is reduced.  Network
   owners also wish to understand the extent to which they can expect



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   different delay characteristics or problems with IPv6 connectivity.
   The goals of our measurements were to help with these topics by
   answering the following questions:

   o  What fraction of most popular Internet sites offer AAAA records?
      How did the World IPv6 Day change the situation?

   o  How do the traffic characteristics differ between IPv4 and IPv6 on
      sites offering AAAA records?  Are the connection failure rates
      similar?  How are RTTs impacted?

   There have been many measurements about some of these aspects from a
   service provider perspective, such as the Google studies on which end
   users have broken connectivity towards them.  Our measurements start
   from a different angle, by assuming a well-working dual-stack
   connectivity on the measurement end, and then probing the rest of the
   Internet to understand, for instance, how likely it is to have IPv6
   connectivity problems, or what are the delay differences between IPv4
   and IPv6 towards the rest of the Internet.  Similar studies have been
   performed by the Comcast IPv6 Adoption Monitor [IPv6Monitor] and RIPE
   NCC [RIPEv6Day].


3.  Measurement Methodology

   We used the top 10,000 sites of the Alexa 1 million most popular
   sites list [Alexa] from June 1st 2011.  For each domain name in the
   list, we performed DNS queries with different host names.  For IPv4
   addresses (A records) we used host name "www" and also performed a
   query with just the domain name.  For IPv6 addresses (AAAA records)
   we used also different combinations of host names that have been used
   for IPv6 sites, namely "www6", "ipv6", "v6", "ipv6.www", "www.ipv6",
   "v6.www", and "www.v6".

   All DNS queries were initiated in the order listed above (first "www"
   and just the domain name for A-records, then "www", domain name, and
   different IPv6-host names for AAAA records) but the queries were done
   in parallel (i.e., without waiting for the previous query to finish).
   The first response for A and AAAA record and the corresponding host
   name were recorded.  The queries had 3 second re-transmission timeout
   and if there wasn't any response for 10 seconds, all remaining
   queries for the site were canceled.  We used a custom-made Perl
   script and the Net::DNS module for the DNS queries.

   The measurement script used a bind9 DNS server running on the same
   host that was performing the measurement.  The DNS cache of the
   server was flushed before each measurement run to be able to detect
   the changes in the DNS records in real-time.  The host, and thus the



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   DNS server, was not part of DNS IPv6 whitelisting agreements.

   After obtaining IP addresses for the site, if a site had both A and
   AAAA records, a simple C-program was used to create TCP connections
   at the same time with IPv4 and IPv6 to the IP addresses discovered
   from the DNS.  The connection setup was repeated for 10 times and the
   connection setup delay was measured by recording the time right
   before and after the connect system call.  The host used for
   measurements is a regular Linux PC with 2.6.32 version kernel and
   dual stack Internet connection via Ethernet.

   The measurements were started one week before the World IPv6 Day (on
   Wednesday, June 1st, 17:30 GMT) and have been running since, once
   every three hours.  One test run takes from two to two and a half
   hours to finish.


4.  Measurement Results

4.1.  DNS Measurements

   When the measurements begun on June 1st, there were 245 sites (2.45%)
   with both A and AAAA record in the top 10,000 sites.  During the
   following days the number of sites was slowly increasing, reaching
   306 sites at the measurement that was started 22:30 GMT on June 7th,
   the evening before the World IPv6 Day. When the World IPv6 Day
   officially started, the following measurement (1:30 GMT) recorded
   already 383 sites, and the next one 472 sites.  During the day number
   of sites with AAAA records peaked at 491 (4.91% of the measured
   10,000 sites) on 19:30 GMT.

   When the World IPv6 Day was over, also the number of AAAA records
   dropped nearly as fast as it had increased just 24 hours earlier.
   However, the number of sites stabilized around 310 and has not
   dropped below 300 since, resulting in over 3% of the top 10,000 sites
   having AAAA records today.

   While 274 sites had IPv6 enabled in their DNS for some of the tested
   host names one day before the World IPv6 Day, only 116 had it for the
   "www" host name that is commonly used when accessing a web site.  The
   number of "www" host names with AAAA records more than tripled during
   the World IPv6 Day reaching 374 sites for 3 consecutive measurement
   runs (i.e., at least for 6 hours).  Also the number of AAAA records
   for the "www" host name dropped steeply after the day and has
   remained around 160 sites since.

   Similar trends, but with larger impact, can be seen if only top 100
   of the most popular sites are taken into considerations.  Here, the



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   number of sites with some of the tested host names having AAAA record
   was initially 14, jumped to 36 during the day, and eventually dropped
   to 13.  Also, while none of the top 100 sites apparently had AAAA
   record for their "www" host before and after the World IPv6 day,
   during the day the number peaked at 30.  Thus, roughly one third of
   the 100 most popular sites was enabling IPv6 for the World IPv6 Day.

4.2.  Delay and Failure Measurements

   Based on the TCP connectivity tests, the IPv6 addresses obtained from
   the DNS appear to work less often than IPv4 addresses.  Also, some
   sites show considerable differences in the RTTs.  However, at the
   time of writing, further analysis of the delay and failure results is
   still ongoing.


5.  Conclusions

   The World IPv6 Day had a very visible impact to the availability of
   content over IPv6, particularly when considering the top 100 content
   providers.  It is difficult to find other examples of bigger one day
   swings in some characteristic of the Internet.  However, real impacts
   to end users were small, given that when dual stack works correctly
   it should not be visible at the user level and that IPv6 availability
   for end users themselves was small.

   The key conclusions are as follows:

   o  The day caused a large jump in the number of content providers
      supporting AAAA on that day.

   o  The day caused a smaller but apparently permanent jump in the
      number of content providers supporting AAAA.

   o  Large and quick swings in the relative amount of IPv4 vs. IPv6
      traffic are possible merely by supporting a dual-stack access
      network and having a few large content providers offer their
      service either globally or to this particular network over IPv6.

   The analysis is not complete, however.  The authors plan to update
   this memo as soon as their analysis of connectivity failures and RTT
   impacts are complete.


6.  Security Considerations

   Security issues have not been discussed in this memo.




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7.  IANA Considerations

   This memo has no IANA implications.


8.  Informative References

   [RFC2460]  Deering, S. and R. Hinden, "Internet Protocol, Version 6
              (IPv6) Specification", RFC 2460, December 1998.

   [IPv6Monitor]
              Comcast and University of Pennsylvania, "IPv6 Adoption
              Monitor", <http://ipv6monitor.comcast.net>.

   [RIPEv6Day]
              RIPE NCC, "World IPv6 Day Measurements",
              <http://v6day.ripe.net/>.

   [Alexa]    Alexa the Web Information Company, "Alexa Top 1,000,000
              Sites",
              <http://s3.amazonaws.com/alexa-static/top-1m.csv.zip>.


Appendix A.  Acknowledgments

   The authors would like to thank Suresh Krishnan, Fredrik Garneij,
   Lorenzo Colitti, Jason Livingood, Alain Durand, Emile Aben, Jan
   Melen, and Tero Kauppinen for interesting discussions in this problem
   space.


Authors' Addresses

   Ari Keranen
   Ericsson
   Jorvas  02420
   Finland

   Email: ari.keranen@ericsson.com


   Jari Arkko
   Ericsson
   Jorvas  02420
   Finland

   Email: jari.arkko@piuha.net




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