Network Working Group V. Bajpai
Internet-Draft J. Schoenwaelder
Intended status: Standards Track Jacobs University Bremen
Expires: January 05, 2014 July 04, 2013
Measuring the Effectiveness of Happy Eyeballs
draft-bajpai-happy-00.txt
Abstract
The IETF has developed solutions that promote a healthy IPv4 and IPv6
co-existence. The happy eyeballs algorithm for instance, provides
recommendations to application developers to help prevent bad user
experience in situations where IPv6 connectivity is broken. This
document describes a metric used to measure the effectiveness of the
happy eyeballs algorithm. The insights uncovered by analysing the
data from multiple locations is discussed.
Status of This Memo
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This Internet-Draft will expire on January 05, 2014.
Copyright Notice
Copyright (c) 2013 IETF Trust and the persons identified as the
document authors. All rights reserved.
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the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Related Work . . . . . . . . . . . . . . . . . . . . . . . . 2
3. Metric . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
4. Implementation . . . . . . . . . . . . . . . . . . . . . . . 3
5. Measurement Trials . . . . . . . . . . . . . . . . . . . . . 4
6. Data Analysis Insights . . . . . . . . . . . . . . . . . . . 4
7. Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . 6
8. Informative References . . . . . . . . . . . . . . . . . . . 6
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 6
1. Introduction
The function getaddrinfo(...) resolves a service name to a list of
endpoints in an order that prioritizes an IPv6-upgrade path
[RFC6724]. The order can dramatically reduce the application's
responsiveness when IPv6 connectivity is broken. The degraded user
experience can be subverted by implementing the happy eyeballs
algorithm [RFC6555]. The algorithm recommends that a host, after
resolving the service name, tries a TCP connect(...) to the first
endpoint. However, instead of waiting for a timeout, it waits for
300ms, after which it must initiate another TCP connect(...) to an
endpoint with a different address family and start a competition to
pick the one that completes first.
This document describes a metric used to measure the effectiveness of
the happy eyeballs algorithm. The insights uncovered by analysing
the data from multiple locations is discussed.
2. Related Work
Fred Baker in [RFC6556] describes metrics and testbed configurations
to measure how quickly an application can reliably establish
connections from a dual-stacked environment. The metrics measure
whether the communication establishment time is same regardless of
the address family and the routing viability available to a dual-
stacked host. The metrics defined in [RFC6556] is different in three
ways:
o DNS is accounted in connection establishment time. Our metric
does not take this into account. Accounting DNS resolution may
invite multiple input factors (slow resolvers) that may bias our
TCP connection establishment time results. In addition, according
to [RFC6555], the 300ms advantage applies to the first address
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family after the getaddrinfo(...) call. From a programming
perspective, an application calls getaddrinfo(...) and that does
its job, regardless of which address family is used.
o The testbed configuration in [RFC6556] is more passive than
active. An external analyser is used to passively observe the
client's traffic using tcpdump. There is no active measurement
test, instead the routers along the path are configured to control
what connectivity route is taken. We on the other hand, have an
active measurement test running on the client. The test is
agnostic to network path configuration since it independently
tries a TCP connection to each connectivity route. It also
actively measures the time taken instead of relying on an external
analyser program.
o The testbed setup in [RFC6556] is designed for a controlled
environment. The router in the path is configured to disrupt all
but one routes to control the prefix used in the connection. As
such, the test is repeated N times with different router
configurations to try all possible permutations of route
connectivity. Our measurement test is agnostic to the network
path and does not require path configuration changes.
3. Metric
We have defined a metric that uses the TCP connection establishment
times as a parameter to measure the algorithm's effectiveness. The
methodology also helps examine the impact of tunneling mechanisms
employed by early adopters. The input parameter of the metric is a
(IP address, port number) tuple and the output is the connection
establishment time, typically measured in microseconds.
4. Implementation
We have developed happy, a simple TCP happy eyeballs probing tool
that conforms to the definition of our metric. It uses non-blocking
connect(...) calls to concurrently establish connections to all
endpoints of a service and measures the elapsed time. The tool
enforces a small delay between concurrent connect(...) calls to avoid
bursty TCP SYN traffic. The initially performed service name
resolution is not accounted in the connection establishment elapsed
time.
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5. Measurement Trials
We use Alexa's top 1M service names as input to prepare a top 100
dual-stacked service names list. We run happy on our internal test-
bed of multiple measurement agents with different flavors of
connectivity ranging from native IPv4, native IPv6, IPv6 tunnel
broker endpoints, Teredo and tunnelled IPv4. The list of Measurement
Agents (MAs) is shown in Table 1.
+------+---------+---------+--------------+-------------+-----------+
| MA # | IPv4 AS | IPv6 AS | City | Country | Platform |
+------+---------+---------+--------------+-------------+-----------+
| 1 | AS680 | AS680 | Bremen | Germany | Mac OS X |
| 2 | AS680 | AS680 | Braunschweig | Germany | GNU/Linux |
| 3 | AS13237 | Teredo | Berlin | Germany | GNU/Linux |
| 4 | AS31334 | AS6939 | Bremen | Germany | OpenWrt |
| 5 | AS680 | AS680 | Bremen | Germany | SamKnows |
| 6 | AS31334 | AS6939 | Bremen | Germany | SamKnows |
| 7 | AS24956 | AS24956 | Braunschweig | Germany | SamKnows |
| 8 | AS3320 | AS3320 | Bremen | Germany | SamKnows |
| 9 | AS5607 | AS5607 | London | England | SamKnows |
| 10 | AS3269 | AS3269 | Torino | Italy | SamKnows |
| 11 | AS8903 | AS8903 | Madrid | Spain | SamKnows |
| 12 | AS2614 | AS2614 | Timisoara | Romania | SamKnows |
| 13 | AS13030 | AS13030 | Olten | Switzerland | SamKnows |
| 14 | AS2856 | AS2856 | Ipswich | England | SamKnows |
+------+---------+---------+--------------+-------------+-----------+
Table 1: A List of Measurement Agents (MAs)
6. Data Analysis Insights
The initial results show higher connection times and variations over
IPv6 as shown in Figure 1.
1e+06 ++-----+-----+------+-----+------+------+-----+------+-----+
+mean (v4) ****** + + + + + + +
+mean (v6) ###### : : : : : : :
* + * * : : : : : : * * *
* : * * : : : : : :** * *
|* : * ##*# : : : : : :** * *
100000 +*.......*.#.**.......................................******
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+*# :**** : * : # : : : * ** *
10000 +*#*******.....**#*#*##**#####*##*####*#########*##*#*...*..
+ ** *** : * ****** ********:*******************: * :
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+ * :* : : : : : : *: * :
+ * :* : : : : : : *: * :
+ : : : : : : : : :
+ + + + + + + + + +
1000 ++-----+-----+------+-----+------+------+-----+------+-----+
0 10 20 30 40 50 60 70 80 90
Service Names
Figure 1: service vs {mean_v4, mean_v6}: samsbox1 (30 days, 300ms)
Fig. 1. shows the average TCP connection establishment times for both
IPv4 and IPv6. The Measurement Agent (MA) is a SamKnows probe
connected at Jacobs University Bremen. It receives IPv4 and IPv6
connectivity via German Research Network (DFN) [AS 680]. A PDF
rendering of the plot is available at [mean].
1e+06 ++-----+-----+------+-----+------+------+-----+------+-----+
+std (v4) ****** + + + + + + +
+std (v6) ###### : : : : : : :
+ + + : : : : : : # :
100000 ++.......*...**..........................................#.*
+ : * ##** : : : : : : * # *
* # : * # ** : # : : : :***# *
#* # # : * **#*#* * #*# # # #: # : :***##*
10000 #*.#.*..**.**..**#..*.#**.#.#..##*...#..##......*...*.***..*
# *#** *** * : **** * #**#### *#** #* ### :#* #*** # * *
+#*#** **** : * ****#* #**###* *#* # * # # #** #* * # * *
+##*#**#*** : * ****** #********#****************** *# **:
|# :##* : : : * : : : #* *:
1000 ++......#...........................................#.....*.
+ : : : : : : : : :
+ : : : : : : : : :
+ + + + + + + + + +
100 ++-----+-----+------+-----+------+------+-----+------+-----+
0 10 20 30 40 50 60 70 80 90
Service Names
Figure 2: service vs {std_v4, std_v6}: samsbox1 (30 days, 300ms)
Figure 2 shows the standard deviation of the TCP connection
establishment times for both IPv4 and IPv6. The Measurement Agent
(MA) is a SamKnows probe connected at Jacobs University Bremen. It
receives IPv4 and IPv6 connectivity via German Research Network (DFN)
[AS 680]. A PDF rendering of the plot is available at [std].
It appears that an application never uses IPv6 using Teredo except
when IPv4 connectivity is broken. We noticed, that a 300ms advantage
leaves a dual-stacked host only 1% chance to prefer a IPv4 route even
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though it may be significantly faster than IPv6. We also measured
the margin by which happy eyeballs is inhibiting the fastest
available route by comparing the slowness of a happy eyeballed winner
to that of the loser.
7. Conclusions
We have performed a preliminary study on measuring the effectiveness
of happy eyeballs. We noticed several cases where the algorithm does
not select the best route and instead hampers the user experience.
We are working towards running this test on a large-scale measurement
platform to develop a more comprehensive picture to help improve the
algorithm.
8. Informative References
[RFC6555] Wing, D. and A. Yourtchenko, "Happy Eyeballs: Success with
Dual-Stack Hosts", RFC 6555, April 2012.
[RFC6556] Baker, F., "Testing Eyeball Happiness", RFC 6556, April
2012.
[RFC6724] Thaler, D., Draves, R., Matsumoto, A., and T. Chown,
"Default Address Selection for Internet Protocol Version 6
(IPv6)", RFC 6724, September 2012.
[mean] Bajpai, V., "IPv4 and IPv6 Average Connection
Establishment Times", July 2013, <http://cnds.eecs.jacobs-
university.de/users/vbajpai/ietf87-v6ops/
samsbox1-mean.pdf>.
[std] Bajpai, V., "IPv4 and IPv6 Connection Establishment Times
Variations", July 2013, <http://cnds.eecs.jacobs-
university.de/users/vbajpai/ietf87-v6ops/
samsbox1-std.pdf>.
Authors' Addresses
Vaibhav Bajpai
Jacobs University Bremen
Campus Ring 1
28759 Bremen
Germany
Phone: +49 421 200 3112
Email: v.bajpai@jacobs-university.de
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Juergen Schoenwaelder
Jacobs University Bremen
Campus Ring 1
28759 Bremen
Germany
Phone: +49 421 200 3587
Email: j.schoenwaelder@jacobs-university.de
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