NDT-DEV email list created

[Jacques Latour <>]

Hi All!

As some of you may know, .ca (CIRA) is planning to publicly launch our Internet Performance Test site (http://cira.ca/performance and http://performance.cira.ca) next week, it's based on the Flash NDT client, we're using the latest and greatest. We're really excited!!

Right now, we're in beta testing until May 5.

One thing that's bugging me is that we get different performance results based on different buffer size and browsers in a controlled environment.  It seems that we would get better performance results if the flash client uses a bigger buffer, 32K seems to work everywhere, 48K likely candidate for us, and 64K seems to be correct but crashes in Chrome sometimes.  (what's the science behind this number?)

The second thing, the data in the buffer runs from 00 --> FF, so repetitive and compressible (if that's a word :), is that a problem?

So, by reading the C2S spec, it says the following; "must use 8K buffer" but other than with the java client, we get better results for larger buffer size.  See table below and attached document for results.

The NDT Client in the C2S Throughput test MUST use a 8192 Byte buffer to send the packets through the newly opened connection as fast as possible (i.e. without any delays) for 10 seconds. The content of the buffer SHOULD be initialized a single time and sent repeatedly. The contents of the buffer SHOULD avoid repeating content (to avoid any automatic compression mechanisms) and MUST include only US-ASCII printable characters. 

	Chrome		Firefox		IE
BUFFER	DOWNLOAD	UPLOAD	DOWNLOAD	UPLOAD	DOWNLOAD	UPLOAD
8K	27.9 Mbps	6.3 Mbps	26.8 Mbps	4.3 Mbps	26.2 Mbps	4.2 Mbps
8K	26.2 Mbps	6.2 Mbps	26.6 Mbps	4.1 Mbps	27.5 Mbps	4.1 Mbps
16K	29.6 Mbps	10.0 Mbps	28.9 Mbps	6.9 Mbps	23.2 Mbps	6.6 Mbps
16K	27.3 Mbps	9.6 Mbps	22.3 Mbps	6.8 Mbps	23.7 Mbps	7.0 Mbps
32K	28.5 Mbps	10.0 Mbps	24.8 Mbps	8.7 Mbps	25.5 Mbps	8.9 Mbps
32K	29.7 Mbps	9.8 Mbps	26.7 Mbps	9.0 Mbps	28.5 Mbps	8.9 Mbps
48K	28.0 Mbps	10.3 Mbps	28.8 Mbps	9.0 Mbps	25.8 Mbps	9.4 Mbps
48K	29.7 Mbps	9.7 Mbps	23.1 Mbps	9.4 Mbps	26.8 Mbps	9.5 Mbps
64K	25.7 Mbps	9.9 Mbps	23.7 Mbps	9.5 Mbps	21.3 Mbps	9.5 Mbps
64K	28.1 Mbps	10.0 Mbps	28.7 Mbps	9.6 Mbps	26.3 Mbps	9.9 Mbps

 Tests: Videotron FIBE 30 Download / 10 Upload  

What about this known limitation?  Can we run 15 seconds?

(https://code.google.com/p/ndt/wiki/NDTTestMethodology)

Known Limitations (Client-To-Server Throughput Test)

A 10 second test may not be enough time for TCP to reach a steady-state on a high bandwidth, high latency link.

Let me know what you think, any insight, wisdom, assistance would be appreciated!

Thanks!

Jack

Attachment: NDT Testing Buffer Size.docx
Description: NDT Testing Buffer Size.docx