Internet DRAFT - draft-bajpai-happy
draft-bajpai-happy
Network Working Group V. Bajpai
Internet-Draft J. Schoenwaelder
Intended status: Standards Track Jacobs University Bremen
Expires: January 15, 2014 July 14, 2013
Measuring the Effects of Happy Eyeballs
draft-bajpai-happy-01.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 effects of the happy
eyeballs algorithm. The insights uncovered by analysing the data
from multiple locations is discussed.
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 15, 2014.
Copyright Notice
Copyright (c) 2013 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
(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
Bajpai & Schoenwaelder Expires January 15, 2014 [Page 1]
Internet-Draft Measuring Happy Eyeballs July 2013
the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. IPv6 Upgrade Policy . . . . . . . . . . . . . . . . . . . . . 2
3. Happy Eyeballs . . . . . . . . . . . . . . . . . . . . . . . 3
4. Related Work . . . . . . . . . . . . . . . . . . . . . . . . 3
5. Metric . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
6. Implementation . . . . . . . . . . . . . . . . . . . . . . . 4
7. Measurement Trials . . . . . . . . . . . . . . . . . . . . . 5
8. Data Analysis Insights . . . . . . . . . . . . . . . . . . . 5
9. Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . 7
10. Informative References . . . . . . . . . . . . . . . . . . . 7
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 8
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 effects of the
happy eyeballs algorithm. The insights uncovered by analysing the
data from multiple locations is discussed.
2. IPv6 Upgrade Policy
The happy eyeballs algorithm as defined in [RFC6555] biases its path
selection in favor of IPv6 by design. The connection establishment
race has been handicapped for the following reasons:
o Carrier-grade NATs (CGNs) establish a binding for each connection
request. Dual-stack hosts by preferring IPv6 connection routes,
reduce their contention towards the critical IPv4 address space.
o The IPv4 traffic may be billed by Operation Support Systems (OSS)
in some networks. Techniques that help move this traffic to IPv6
networks reduce costs.
Bajpai & Schoenwaelder Expires January 15, 2014 [Page 2]
Internet-Draft Measuring Happy Eyeballs July 2013
o Middleboxes maintain state for each incoming connection request.
If the dual-stacked hosts prefer IPv6 path, the load on load
balancers and peering links reduces automatically. This reduces
the investment on IPv4, and encourages IPv6 migration.
3. Happy Eyeballs
The happy eyeballs algorithm defined in [RFC6555] honors the IPv6
upgrade policy. It is therefore not designed to encourage aggressive
connection requests over IPv4 and IPv6, but instead to satisfy the
following goals:
o The connection requests must be made in an order that honors the
destination-address selection policy as defined in [RFC6724],
unless overriden by user or network configuration. The client
must prefer IPv6 over IPv4 whenever the policy is not known.
o The connection initiation must quickly fallback to IPv4 to reduce
the wait times for a dual-stack host in situations where the IPv6
path is broken.
o The network path and destination servers must not be thrashed by
mere doubling of traffic by making simulataneous connection
requests over IPv4 and IPv6. The connection requests over IPv6
must be given a fair chance to succeed to reduce load on IPv4,
before a connection over IPv4 is attempted.
However, applications on top of TCP will not be happy eyeballed only
in scenarios where IPv6 connectivity is broken, but also in scenarios
where the dual-stack host enjoys comparable IPv6 connectivity. We
want to measure how much imposition does such a user experience in
reality by measuring the effects of the happy eyeballs timer value.
The recommended timer value is 150-250ms [RFC6555]. However, Chrome
uses 300ms. Firefox appears to be using 250ms while an early open-
source implementation of happy eyeballs seems to recommend 100ms
[Perreault]. We want to affirm the right value by measuring TCP
connection establishment times experienced by dual-stacked hosts in
real environments over IPv4 and IPv6.
4. Related Work
Bajpai & Schoenwaelder Expires January 15, 2014 [Page 3]
Internet-Draft Measuring Happy Eyeballs July 2013
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
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.
5. Metric
We have defined a metric that uses the TCP connection establishment
times as a parameter to measure the algorithm's effects. 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.
6. Implementation
Bajpai & Schoenwaelder Expires January 15, 2014 [Page 4]
Internet-Draft Measuring Happy Eyeballs July 2013
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.
7. 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)
8. Data Analysis Insights
The initial results show higher connection times and variations over
IPv6 as shown in Figure 1. The services themselves may not be
comparable amongst one another due to the sheer nature of different
routing paths traversed by the packets.
1e+06 ++-----+-----+------+-----+------+------+-----+------+-----+
+mean (v4) ****** + + + + + + +
Bajpai & Schoenwaelder Expires January 15, 2014 [Page 5]
Internet-Draft Measuring Happy Eyeballs July 2013
+mean (v6) ###### : : : : : : :
* + * * : : : : : : * * *
* : * * : : : : : :** * *
|* : * ##*# : : : : : :** * *
100000 +*.......*.#.**.......................................******
+* : *##*:* : : : : : #******
+* : **#*:* : : : : : * *****
+* :*****:*# : : : : : * ****
+*# :**** : * : # : : : * ** *
10000 +*#*******.....**#*#*##**#####*##*####*#########*##*#*...*..
+ ** *** : * ****** ********:*******************: * :
+ * :* : : : : : : *: * :
+ * :* : : : : : : *: * :
+ : : : : : : : : :
+ + + + + + + + + +
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].
Bajpai & Schoenwaelder Expires January 15, 2014 [Page 6]
Internet-Draft Measuring Happy Eyeballs July 2013
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 in
situations where IPv4 reachability of the destination service is
broken. We noticed, that a 300ms advantage leaves a dual-stacked
host only 1% chance to prefer a IPv4 route even 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.
9. Conclusions
We have performed a preliminary study on measuring the effects 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.
10. Informative References
Bajpai & Schoenwaelder Expires January 15, 2014 [Page 7]
Internet-Draft Measuring Happy Eyeballs July 2013
[I-D.ietf-6man-addr-select-opt]
Matsumoto, A., Fujisaki, T., and T. Chown, "Distributing
Address Selection Policy using DHCPv6", draft-ietf-6man-
addr-select-opt-10 (work in progress), April 2013.
[Perreault]
Perreault, S., "Happy Eyeballs in Erlang", July 2013,
<http://www.viagenie.ca/news/
index.html#happy_eyeballs_erlang>.
[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
Bajpai & Schoenwaelder Expires January 15, 2014 [Page 8]
Internet-Draft Measuring Happy Eyeballs July 2013
Juergen Schoenwaelder
Jacobs University Bremen
Campus Ring 1
28759 Bremen
Germany
Phone: +49 421 200 3587
Email: j.schoenwaelder@jacobs-university.de
Bajpai & Schoenwaelder Expires January 15, 2014 [Page 9]
