deblin
Dark Side of the Moon
Premium,MVM
join:2001-09-01
Middletown, DE
 ·Verizon FIOS
 ·Comcast Workplace
 ·DSL EXTREME
| reply to d_l
Re: ACK Prioritization: a 4100/4100b vs. 5360 shootout
Great work d_l  , thanks!
Bottom line - if you have an older modem, consider asking AT&T for the 4100 or go to best buy and shell out the $75 for the modem, it's worth it. Not only do they typically improve line stats and line stability over older modems, they have this added advantage.
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Hello...is there anybody in there? |
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d_l
Barsoom
Premium,MVM
join:2002-12-08
Reno, NV
| I want to re-emphasize the YMMV part. The download test I used involved downloading from a relatively high latency, east coast site. The packets had to travel from NY to CA and then back here to NV! This is the type of situation where larger RWINs shine.
The improvement from using a larger RWIN can be seen in the tighter packet speeds on the part of the download before and after the upload portion. More of the packets are nearly at 650 KB/second speed during normal downloading when the RWIN was at ~128K
The ACK prioritization effects clearly interact with and affect the TCP/IP layer. So a larger RWIN might not work as well for someone in the middle of the country that has shorter routes (lower latency) to a download server |
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kruser
Premium
join:2002-06-01
Chesterfield, MO
clubs:
·AT&T Southwest
| 
Baseline no upload | 
2wire with 65535 RWIN | 
2wire with 127776 RWIN | 
2210 with 65535 RWIN | 
2210 with 127776 RWIN |
The other tests were run with the same download running along with a large FTP upload running simultaneously. |
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d_l
Barsoom
Premium,MVM
join:2002-12-08
Reno, NV
|  Thanks for doing those! They clearly show that the 2Wire has minimal ACK prioritization. As a very rough, eyeball guesstimate, it looks like the speeds during upload saturation might be about 160 KB/sec with 65K RWIN which would give about 25% or less of normal throughput (160/640). This agrees with your previous tests plotted on my first graph.
The 2210 doesn't look to have much ACK prioritization either. Maybe its speeds during upload saturation might be 150-180 KB which would be 23-28% of normal throughput. This is a little better than your previous testing on the AT&T speed tests, but then again it is really difficult to make a good estimate of average speeds from those throughput graphs.
This pretty much shows that the 2wire 1800HG and the 2210 suck for simultaneous download and uploads unless you use a larger RWIN and that can cause problems. I'm finding that the AT&T speeds tests won't always run in the evenings with an ~128K RWIN. |
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