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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
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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
   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



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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.  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.



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   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










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   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





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   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) ******   +     +      +      +     +      +     +



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        +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].

























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   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




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   [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











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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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