Upload slowdowns during upload process

alra111

alra111

Registered
I have noticed that while uploading large files (I am connected via Airport on my iMac to a home network), an upload that starts off at 100KB/sec can end up slowing down to about 50KB/sec. What causes this, and is there a workaround? Would I get better speed during uploads if I connected directly to my modem via an Ethernet cable?

Using Comcast, if that info helps...

*UPDATE* I just tried connecting the iMac directly to the router via an Ethernet cable, and noticed the same slowdown. Do I need a more advanced router?

Thanks,
Alra111
 
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Comcast employs a technology they call "Power Boost" or "Power Booster". What it does is greatly accelerate the transmission speed of a transfer only for a set amount of data initially, then it slows down.

For example, if you were to download an 8MB file, you would probably see "fast" speeds throughout the transfer, simply because Power Boost works for the first 10 or 20MB or so. Now, if you were to download an 80MB file, you'd probably see fast speeds up to about 10 or 20MB, then you'd see the transfer slow down.

This technology makes it appear as if you're getting great speeds, simply because web pages and small transfers like that appear to go at lightning speed... but on longer, bigger transfers, your speed decreases after you cross a certain size/time threshhold.

Could this be what you're seeing with Comcast? Do you have any other computers in the house that exhibit fast speeds throughout the entire transfer?
 
Some browsers start downloading before you really start it (it does so in the background, anticipating for a potential future download). So it looks fast at the beginning.
 
As far as I know, neither Safari, Firefox, Camino, Flock nor Opera on Mac OS X does this. (without 3rd-party add-ons/plug-ins). I doubt that is what he is experiencing.
 
Firefox does it when you download to a file, it starts downloading as soon as you click the link, before you select the download destination.
 
True, it does, but it doesn't display an "inflated" download rate in the Downloads window. It simply displays the progress bar filled as much as it's downloaded already and the current download rate. You can click on a link to download, say, a 10MB file, and when it asks you for a download destination, let it sit there for a few moments (let's say, until about 5MB are downloaded). When you finally choose a download destination, the Downloads window will open with the progress bar halfway filled (5MB = 50% of 10MB) and the current download rate. It doesn't start with an empty progress bar, then quickly progress to 50% while displaying a download rate of several megabytes per second.

I still don't think that's what he's seeing.
 
ElDiabloConCaca said:
Comcast employs a technology they call "Power Boost" or "Power Booster". What it does is greatly accelerate the transmission speed of a transfer only for a set amount of data initially, then it slows down.

For example, if you were to download an 8MB file, you would probably see "fast" speeds throughout the transfer, simply because Power Boost works for the first 10 or 20MB or so. Now, if you were to download an 80MB file, you'd probably see fast speeds up to about 10 or 20MB, then you'd see the transfer slow down.

This technology makes it appear as if you're getting great speeds, simply because web pages and small transfers like that appear to go at lightning speed... but on longer, bigger transfers, your speed decreases after you cross a certain size/time threshhold.

Could this be what you're seeing with Comcast? Do you have any other computers in the house that exhibit fast speeds throughout the entire transfer?
Click to expand...

I don't notice much problems with downloads. It is strictly with uploads. But what you said sounds like something a big bastardly corporation like Comcast would do.
 
I've had a huge slowdown in uploads since the end of January. There are many possible causes, but I have to say, it's really odd when you do speedtests and get 14,000 kbps download (they used to be about 5000 so they have tweaked something) and the upload is 18kbps (when you're lucky... it's actually blipped below 1 on more than a few occasions) Watching FTP in progress, or using net diagnostics you can actually see the slow down from slow to REALLY SLOW to ... practically not moving at all. I dont think it has to do with the Mac specifically, but it's possible, I guess. The downloads are also being interrupted by an intermittent staccato, so it's a pop pop pop kind of thing, not a steady flow of data. You can literally see it in Cyberduck, for example, as the FTP is 'progressing'. I'm using macbook pro 2.3 and an airport express. Without the router the download speeds are a little faster, but the upload is still crippled. Just tried adding the apple broadband 'fix' and I see no noticeable difference. It was supposed to increase the limits on the buffer (?) My downloads start fast and are at least passable, since more likely the actual speed downloading is closer to 5 or 6000 sustained) ... and then upload chokes. Every now and then it comes back to close to 300 (where it belongs) so I seriously doubt it's a modem, or a Mac OS problem... You may be experiencing the same thing. I think it's a comcast issue.

You might want to check your modem - if you have a motorola you may need to get a configuration fix ... the updates that comcast is sending are not the right flavor for the modem and error messages show up in the log. Can't say if that 'fix' will help or not... I've requested a ticket but I'm still waiting for mine). It might be worth checking your modem log to see if that's happening to you.

Meanwhile, if anyone has any ideas about how to tweak settings to enhance the upload speed, I'd love to hear about it ... Thanks! (using 10.4.8)
 
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