Andrew Cooke | Contents | Latest | RSS | Twitter | Previous | Next

C[omp]ute

Welcome to my blog, which was once a mailing list of the same name and is still generated by mail. Please reply via the "comment" links.

Always interested in offers/projects/new ideas. Eclectic experience in fields like: numerical computing; Python web; Java enterprise; functional languages; GPGPU; SQL databases; etc. Based in Santiago, Chile; telecommute worldwide. CV; email.

Personal Projects

Lepl parser for Python.

Colorless Green.

Photography around Santiago.

SVG experiment.

Professional Portfolio

Calibration of seismometers.

Data access via web services.

Cache rewrite.

Extending OpenSSH.

C-ORM: docs, API.

Last 100 entries

[Bike] Lessons From 2 Leading 2 Trailing; [Link] Veg Restaurants in Santiago; [Link] List of Contemporary Latin American Authors; [Bike] FTHR; [Link] Whoa - NSA Reduces Collection (of US Residents); [Link] Red Bull's Breitbart; [Link] Linux Threads; [Link] Punycode; [Link] Bull / Girl Statues on Wall Street; [Link] Beautiful Chair Video; Update: Lower Pressures; [Link] Neat Python Exceptions; [Link] Fix for Windows 10 to Avoid Ads; [Link] Attacks on ZRTP; [Link] UK Jazz Invasion; [Review] Cuba; [Link] Aricle on Gender Reversal of US Presidential Debate; {OpenSuse] Fix for Network Offline in Updater Applet; [Link] Parkinson's Related to Gut Flora; Farellones Bike Park; [Meta] Tags; Update: Second Ride; Schwalbe Thunder Burt 2.1 v Continental X-King 2.4; Mountain Biking in Santiago; Books on Ethics; Security Fail from Command Driven Interface; Everything Old is New Again; Interesting Take on Trump's Lies; Chutney v6; References on Entropy; Amusing "Alexa.." broadcast; The Shame of Chile's Education System; Playing mp4 gifs in Firefox on Opensuses Leap 42.2; Concurrency at Microsoft; Globalisation: Uk -> Chile; OpenSuse 42.2 and Synaptics Touch-Pads; Even; Cherry Jam; Lebanese Writer Amin Maalouf; C++ - it's the language of the future; Learning From Trump; Chinese Writer Hu Fayun; And; Apricot Jam; Also; Excellent Article on USA Politics; Oh Metafilter; Prejudice Against The Rurals; Also, Zizek; Trump; Why Trump Won; Doxygen + Latex on CentOS 6; SMASH - Solve 5 Biggest Problems in Physics; Good article on racism, brexit, and social divides; Grandaddy are back!; Consciousness From Max Entropy; Democrats; Harvard Will Fix Black Poverty; Modelling Bicycle Wheels; Amusing Polling Outlier; If Labour keeps telling working class people...; Populism and Choice; Books on Defeat; Enrique Ferrari - Argentine Author; Transcript of German Scientists on Learning of Hiroshima; Calvert Journal; Owen Jones on Twitter; Possible Japanese Authors; Complex American Literature; Chutney v5; Weird Componentized Virus; Interesting Argentinian Author - Antonio Di Benedetto; Useful Thread on MetaPhysics; RAND on fighting online anarchy (2001); NSA Hacked; Very Good LRB Article on Brexit; Nussbaum on Anger; Tasting; Apple + Kiwi Jam; Hit Me; Sudoku - CSP + Chaos; Recycling Electronics In Santiago; Vector Displays in OpenGL; And Anti-Aliased; OpenGL - Render via Intermediate Texture; And Garmin Connect; Using Garmin Forerunner 230 With Linux; (Beating Dead Horse) StackOverflow; Current State of Justice in China; Axiom of Determinacy; Ewww; Fee Chaos Book; Course on Differential Geometry; Okay, but...; Sparse Matrices, Deep Learning; Sounds Bad; Applebaum Rape; Tomato Chutney v4; Have to add...; Culturally Liberal and Nothing More; Weird Finite / Infinite Result

© 2006-2017 Andrew Cooke (site) / post authors (content).

Traffic Shaping by VTR

From: "andrew cooke" <andrew@...>

Date: Wed, 16 Jul 2008 19:48:10 -0400 (CLT)

I am trying to upload the patched NVidia CUDA SDK, but my connection is
running so slowly it may take all night.

There's information on VTR (my ISP) here - http://www.neutralidadsi.org

Here are some details, taken from an email I just sent to the (helpful)
guy that runs acooke.org:

----------

hi,

sorry to bother you, but wonder if you had any idea what might be
happening.  i am trying to upload a file to acooke.org and it is extremely
slow (around 10MB an hour).  it's been this way all day and i have noticed
a similar problem with other files the last few days.

looking at the "meter" in sftp there are bursts of normal (ie fast)
downloading, and then the transmissions "stalls".  looking at the tcp
packets, the connection seems to simply disappear - a burst of fast
packets go through, then the system freezes, then after what i assume is a
timeout period (a minute or two - it varies) there's a retransmission,
sometimes some duplicate acks and more retransmissions, and then things
pick up again.

so data get through for maybe 10 seconds, then there's a pause for a
minute or two, then the cycle repeats.  this is quite regular and the
connection never actually fails.

my isp (vtr chile) has a reputation for throttling connections, but there
are no reset packets.  i don't understand things well enough to say more
than that.

tracepath gives the following:
qp6c ~: tracepath acooke.org
 1:  190.160.224.58 (190.160.224.58)                        0.189ms pmtu 1500
 1:  no reply
 2:  no reply
 3:  no reply
 4:  Hurrican-Electric-LLC.TenGigabitEthernet1-4.ar2.SJC2.gblx.net
(64.214.174.246) asymm  7 145.798ms
 5:  10gigabitethernet1-2.core1.fmt2.he.net (72.52.81.177) asymm  8 148.771ms
 6:  acooke.org (72.52.113.196)                           asymm  9
159.615ms !H
     Resume: pmtu 1500

any idea?  has anyone else reported the same thing?  as far as i know i am
dealing with the only high speed internet service in town here, and the
service is terrible.  i will try contacting them tomorrow, but don't
expect to get anywhere.

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

Andrew

More Evidence

From: "andrew cooke" <andrew@...>

Date: Thu, 17 Jul 2008 06:00:42 -0400 (CLT)

Last night I found that:

- Using sftp from home to acooke.org was slow
- Using sftp from acooke.org to home was fast

So I ssh'ed into acooke.org and pulled files across rather than trying to
send them.  The only differences I can see in the two are:

- The role of client and server are reversed
- acooke.org doesn't use the standard port (22) for ssh

My guess is that VTR decided to limit traffic on non-standard ports.

Also, this morning, thing seem to be working OK again.  While last night
they got progressively worse (by the end it was difficult to type commands
in ssh it was so slow).  My guess there is that this is progressive (as
part of re-doing this site I have been transferring more data than
normal).

In summary, I think that what is happening is that:

- VTR appear to be "traffic shaping"
- They may be leaving standard ports alone
- They appear to progressively degrade performance
- If necessary, using pulling files over FTP is a workaround
  (because either the port or client changes)

We pay for a good (expensive) connection....

I'm going to try looking for a different provider today, but changing
things here is a real hassle (and I think it's a monopoly - there's only
one cable company).

Andrew

Comment on this post