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 working documents as Internet-Drafts. The list of current Internet- Drafts is at http://datatracker.ietf.org/drafts/current/. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any 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 Keranen & Arkko Expires January 5, 2012 [Page 1] Internet-Draft IPv6 Day Measurements July 2011 (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. Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License. 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 Keranen & Arkko Expires January 5, 2012 [Page 2] Internet-Draft IPv6 Day Measurements July 2011 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 Keranen & Arkko Expires January 5, 2012 [Page 3] Internet-Draft IPv6 Day Measurements July 2011 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 Keranen & Arkko Expires January 5, 2012 [Page 4] Internet-Draft IPv6 Day Measurements July 2011 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 Keranen & Arkko Expires January 5, 2012 [Page 5] Internet-Draft IPv6 Day Measurements July 2011 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. Keranen & Arkko Expires January 5, 2012 [Page 6] Internet-Draft IPv6 Day Measurements July 2011 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", . [RIPEv6Day] RIPE NCC, "World IPv6 Day Measurements", . [Alexa] Alexa the Web Information Company, "Alexa Top 1,000,000 Sites", . 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 Keranen & Arkko Expires January 5, 2012 [Page 7]