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https://github.com/apenwarr/blip

A tool for seeing your Internet latency. Try it at http://gfblip.appspot.com/
https://github.com/apenwarr/blip

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A tool for seeing your Internet latency. Try it at http://gfblip.appspot.com/

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README 

        
blip: a tool for seeing your Internet latency

=============================================

Tip:

----



On your PC, laptop, tablet, phone, or iPod, try adding a

bookmark to http://gfblip.appspot.com/ to your home screen

for easy access.






Too long, don't read:

---------------------



 - Go to http://gfblip.appspot.com/



 - It should work on any PC, laptop, tablet, phone, or iPod

   with javascript and HTML canvas support (which means

   almost everything nowadays).



 - X axis is time. Y axis is milliseconds of latency.



 - Green blips are your ping time to gstatic.com (a very

   fast site that should be close to you wherever you are).



 - Blue blips are your ping time to apenwarr.ca ("a site on

   the Internet").  It should be slower than gstatic.com. 

   How much slower depends on how lucky you are.



 - Red blips mean something sucks.

 

 - A good Internet+Wifi connection should have no red

   blips.  And lower latency is better than higher latency.

 

 - We send blips out as fast as they come back, up to 100

   per second, so you can notice very small variations.



 - If you watch the blip output while you do different

   things (switch wifi networks, start Youtube videos

   playing, walk around), you can immediately see what

   impact that change has on the quality of your Internet

   connection.



Even longer, don't read:

------------------------



People think more bandwidth will make your Internet

connection seem faster, but that isn't even close to the

whole story.  There are three interrelated things you need

to care about:



  - bandwidth

  - latency

  - packet loss.



Bandwidth means, once things get going, how fast you can

download.  But "once things get going" can take a really

long time.  In fact, it can take longer than the whole

download!  This is especially true for simple web pages, or

web pages made up of a bunch of tiny pieces, which is very

common on today's web.



That's where latency comes in.  Latency is the time it

takes to make a round trip to the server.  Really good web

designers know how to minimize the number of round trips,

or at least do more round trips at the same time - which

makes their pages load faster on everyone's connection. 

But every web page, whether optimized or not, automatically

benefits pretty much proportionally to your network

latency.  Cut latency in half, and most pages will load

about twice as fast.



Packet loss is the third component, and it's often

forgotten.  If you run the 'ping' program, which most

people don't do and which is hard or impossible to do from

many modern Internet devices (phones, tablets, etc), it

will show you how many packets are dropped, and how many

got through.  Unfortunately, most people don't run ping

more than once per second, which gives a pretty low

resolution; if you have a really brief outage, you might

not even see it with ping.  Plus, on the modern Internet,

packet loss is hard to measure - you can't do it with a web

browser.  And it's not that useful anyway, since real web

pages don't see "packet loss." On the web (and any

TCP-based protocol), packet loss translates into packet

retransmissions, which means latency in some cases is 2, 3,

or more times higher than usual.  If you have significant

packet loss (say, 1% or more), your web performance will

totally suck eggs even if your bandwidth and latency are

both fantastic.



Blip is an end-to-end testing tool designed to let you

measure the latter two elements: latency and packet loss. 

These are the real indicators of your web browsing

performance.  It doesn't attempt to measure bandwidth; for

that there's always good old http://speedtest.net/.  (By

the way, next time you're visiting speedtest.net, watch how

the "download speedometer" dial starts off low and increases

over time.  That's what I mean when I say you might be done

downloading by the time "things get going.")



How is blip an end-to-end tool?  Simple.  It's written in

pure javascript, so it runs purely in your browser, without

needing a server-side component.  It makes real requests to

real http servers, rather than using synthetic "ping"

packets.  Then it measures the turnaround time on those

requests and plots them on a graph.  And it does this up to

100 times per second, so you can see your network quality

in high resolution.  It's the next best thing to actually

browsing the web, except you get a pretty graph instead of

"hmm, that page loaded kinda slowly today."



Blip doesn't attempt to interpret the results for you; it

just makes the plot in real time.  If you try experimenting

with it in a few different conditions, you can get an

intuitive feel for what those conditions mean to the graph -

and the graph can give you an intuitive feel for how

sucky your web browsing performance will be under those

conditions.



Here are some observations I've made using blip:



 - If there's a red blip more than once every minute or so,

   your web browsing will be noticeably more annoying than

   if there isn't.  Yes, real wifi connections exist, even

   in crowded buildings, with *zero* red blips.  That

   should be your goal.

 

 - One of my tablet devices produces red blips even when

   another device, sitting right next to it, on the same

   access point, does not.

 

 - Some wifi routers give decent speedtest.net results most

   of the time, and terrible speedtest.net results other

   times.  This is usually because they get angry and start

   losing packets at random times, which is easy to see with blip.

 

 - You can walk around your apartment or house and find out

   exactly where the wifi "dead zones" are, within seconds. 

   It's kind of like a geiger counter; wave it around and

   see what happens to the clicks.

 

 - "Wifi signal strength" meters are all a bunch of evil

   liars.  Don't trust them.  Wondering why your Internet

   is slow even with 5 bars?  Don't believe the hype.  Blip

   will show you the truth.

 

 - For me, on a wired ethernet network I can get about 15ms

   (or less from some locations) green blips.  On wifi it's more

   like 30-50ms.  On 3G cellular, with a really good signal

   (eg. outdoors with no obstructions) the best I get is

   about 100ms.  With obstructions, it's normally more like

   200ms.  And yes, the ratios between these numbers really

   do seem like the performance difference I see when web

   browsing.

 

 - 3G cellular networks, surprisingly, seem to have far

   fewer red blips than typical "public" wifi signals (eg. 

   ones in malls, parks, etc), even in moderately crowded

   area.  So even though the latency ("ping time") might

   look better on public wifi, the packet loss (shown as a

   nonzero number of red blips) means web browsing will be

   cruddy.  That matches my experience, but now I can

   measure it for real.



The Stupid Part

---------------



So you might be wondering, hey, how did you make a

javascript applet ping these arbitrary servers?  What about

cross-domain request protection?



Answer: I did it by just making the queries anyway, and

seeing how long it takes to get the error message back that

my request was refused because of cross-domain request

protection.  Yes, this results in an infinite number of

error messages to your javascript console.  Don't look at your

javascript console and you'll be fine.  Trust me on this.



The Fiddly Bits

---------------



blip is open source software released under the Apache

license.  See the file COPYING and comments inside the code

for more details.



You can get the source code at: http://github.com/apenwarr/blip



If you want to discuss this tool, you can join the

[email protected] mailing list.  You don't need a

Google Account to subscribe!  Just send an email to

[email protected] and you can join.



blip probably needs lots of fancy new features.  It's the

first program I've ever written using HTML Canvas for

display (which is really fun), so I probably did some dumb

things.  Javascript is also not my first choice of

programming language (yet?) so I probably did some even dumber

things.  Send pull requests.  That is all.



  -- apenwarr