1.
Measuring latency
from the browser
Agustín Formoso
agustin@lacnic.net
LACNIC Labs
simon.lacnic.net

2.
@proyectosimonhttp://simon.lacnic.net
The project
The problem
• Connectivity in LAC is good
but not optimal
• Presence of IXPs, but inter-
country connectivity still has to
be improved
• Information about connectivity
is not easy to find or updated
The solution
• Objective
Provide representative and
up-to-date connectivity
measurements to anyone
interested in them
• How
Latency measurements from
many origins, to many
destinations, via different
protocols

3.
@proyectosimonhttp://simon.lacnic.net
Why bother with the
browser?
Pros
• Standard and widely-used
technologies
• Ran at the end user
• Can trigger measurements
automatically
• Scales fast
Cons
• Browser and operating system
combination differences
- TCP connections are handled
differently by browser and OS
combination!
- Browser Javascript engines vary
- OSes handle processes
differently
• Need of normalising different
environments!

4.
@proyectosimonhttp://simon.lacnic.net
Why bother with the
browser?

5.
@proyectosimonhttp://simon.lacnic.net
Testing our tool in
Browserstack
• Cloud-based testing service aimed
at web developers to check the
look & feel and responsiveness of
their sites
• We use it to run our Javascript tool
over many different OS and
browser combination
• We used automated Selenium tests

6.
@proyectosimonhttp://simon.lacnic.net
The test: Javascript tool
• Ran in the virtual instance
• Fixed origin, fixed destination
• Simple HTTP GET
• Time the RTT
• Parallel sessions with a reference environment always present

7.
@proyectosimonhttp://simon.lacnic.net
Normalising results
Windows
7
Windows
8.1
OS X
Windows
XP
Windows
8
Chrome
family
0 +1.9 -7.2 -1.4 +0.1
Firefox
family
-3.9 -2.8 -11.4 -4.8 -5.6
Our reference environment[Results are in ms]

8.
@proyectosimonhttp://simon.lacnic.net
Normalising results
• Two distinct behaviours
- Firefox vs. Chrome
- OS X versus the rest
[Lighter blue means faster]

9.
@proyectosimonhttp://simon.lacnic.net
LAC regional matrix
[Lighter blue means faster]

10.
@proyectosimonhttp://simon.lacnic.net
Still…
• We need more tests! (currently at ~1.5K daily)
• Uncertainties on virtualisation
• No mobile or Linux yet (~8% of seen traffic)

11.
@proyectosimonhttp://simon.lacnic.net
Conclusions
• The browser: great tool for delivering large-scale
measurements but
- Huge variety
- Measurement noise can be high

12.
Thank you!
Q&A