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[ndt-dev] Websocket Client - Upload Speed Problem

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  • From: Don Slaunwhite <>
  • To: "" <>
  • Subject: [ndt-dev] Websocket Client - Upload Speed Problem
  • Date: Mon, 6 Jul 2015 18:45:33 +0000
  • Accept-language: en-CA, en-US

Hi Everyone,


My name is Don Slaunwhite and I’m a Product Manager at CIRA. We have been utilizing the NDT tests as part of our Internet Performance Test up here in Canada.


We have been working on transitioning to the Websocket client with our test, but we have been seeing some very different results in upload speeds as compared to the flash client.


We did a lot of internal/external testing and in every case the upload speeds for the websocket version were lower (most times significantly) than our current flash client. The download speeds are comparable, with websocket usually coming in a bit faster


For example we setup a VM at Amazon to run some (hopefully!) controlled tests. Using Chrome and Firefox.


Chrome Averages based on ~200 tests

Flash 19.3Mpbs Upload

Flash 49.8Mpbs Download

Websocket  9.3Mpbs Upload

Websocket  54.3Mpbs Download


Firefox Averages based on ~300 tests

Flash 27.4 Mpbs Upload

Flash 50.1 Mpbs Download

Websocket  11.1 Mpbs Upload

Websocket  57.2 Mpbs Download


In each case the websocket upload is significantly lower. I’m trying to determine if this is expected behaviour with the websocket code. If not what possible items might be causing this type of speed degradation.


We are running with client versions 3.7.0 (Flash has a buffer size of 32K) against mlab servers in Toronto.


I realize there will be new functionality/capability with the multiple stream releases, but right now I’d like to try and focus on one major change at a time, so any ideas on speed differences between Flash and Websocket using just 3.7.0 would be really helpful.





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