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+--- Thread: Large Files Transfers on Comcast (/showthread.php?tid=44572)
Large Files Transfers on Comcast - prof - 12-02-2007
A friend and I are trying to transfer a large FCP file (5 gig) between us using AFP
filesharing. We've managed to connect OK, but obviously it's going to take awhile
to transfer a file of that size. The problem is that the transfer rates seems to drop
sharply after a short while and that makes an already long transfer even longer.
My friend believes it's because Comcast is throttling down large transfers using
Sandvine to thwart bit torrent downloads. If this is true, it's completely unfair that
it affects anyone sending large files of their own personal data. Is there anyway
to create a secure or encrypted connection to get around this??
TIA,
Prof
Re: Large Files Transfers on Comcast - GGD - 12-02-2007
Do you have any idea what the actual transfer rate is after it drops, and how long is "a short while".
What you're seeing might be Comcast's "Speed Boost" feature that gives you an initial burst at a very fast speed but then slows down to your "normal" speed after several seconds.
When you get down to your normal speed, then the transfer will be limited by the slowest of the Upload/Download speeds of both ends, which might a 768kb/sec upload speed. And at that speed, 5GB might take about 15 hours. At 1mb/sec it's around 11 hours.
While the transfer is occurring you can look at Activity Monitor and the Network tab to see a graph of your transfer speeds and the current rates. Note that those are in K Bytes instead of K bits that your internet speed is normally referred to, so multiply the Activity numbers by 8 to get kilobits or megabits per second.
Re: Large Files Transfers on Comcast - ho'ard - 12-02-2007
There was some discussion here, that made a credible case for Comcast's "throttling"-- it's not something they're doing secretly, they're informing users of it. Your friend seem to be absolutely right.
Re: Large Files Transfers on Comcast - MacMagus - 12-02-2007
Yes, Comcast throttles large file transfers.
It's not quite the same as the BitTorrent issue. It's done on different ports and they don't need to send maliciously crafted packets to each party to slow down a normal network file transfer.
They slam me when I xfer large files. I start out with perhaps a 140kps upstream speed and that quickly drops down to around 76kps after a minute or so. This is a royal PITA as I often have to exchange huge Photoshop files with colleagues.
You may also notice that your downstream speed is throttled during large file transfers and for about 2 minutes after a file transfer is concluded.
They really need to be bitch-slapped. Hard.
Re: Large Files Transfers on Comcast - ho'ard - 12-02-2007
I did try to find the past thread about this but wasn't successful. I think I need to take a course on choosing search terms. I figured I couldn't go wrong with "Comcast" . . .
Re: Large Files Transfers on Comcast - endymion - 12-02-2007
All I know is I can't get iChatAV to work for extended periods between two Comcast (home) cable internet connections that are about 13 miles apart and ride the Comcast network the entire way. :-(
g=
Re: Large Files Transfers on Comcast - jdc - 12-02-2007
5 gigs would be sent faster using FedEx
Re: Large Files Transfers on Comcast - The Grim Ninja - 12-02-2007
GGD is right, it's not a flaw, it's a "feature"
"Powerboost gives you some extra oomph so you can send large files faster" Or something like that, says the boy in the commercial. Of course, in the tiny text at the bottom of the ad it says "First 10MB of a file" Yeah, as if that extra speed really makes a difference for someone downloading a whole 10MB. 10MB at 800KB/sec vs 1200KB/sec really isn't a big difference than, say a 5GB file...
Also, as far as I can tell, the upload limit is a bit different. It *seems* to be the first 500KB-1MB of a file.
Also, once you reach that 'limit' for the powerboost 'feature', you connection needs to be idle for several minutes before you can take advantage of it again. Personally, I consider it a big F_U_. It's basically them saying "hey, look what we can do! Do ya like that!? Yeah? Well too damn bad, cause you've reached the limit. Now pay your bill, we just raised the rates!
Re: Large Files Transfers on Comcast - prof - 12-02-2007
[quote MacMagus]Yes, Comcast throttles large file transfers.
It's not quite the same as the BitTorrent issue. It's done on different ports and they don't need to send maliciously crafted packets to each party to slow down a normal network file transfer.
They slam me when I xfer large files. I start out with perhaps a 140kps upstream speed and that quickly drops down to around 76kps after a minute or so. This is a royal PITA as I often have to exchange huge Photoshop files with colleagues.
You may also notice that your downstream speed is throttled during large file transfers and for about 2 minutes after a file transfer is concluded. They really need to be bitch-slapped. Hard.
This mirrors my experience as well. I'm aware of the speed boost factor but what's happening on large files is actually the complete opposite. Comcast advertises that they give you all this incredible speed but when you actually use it they throttle you for doing so. Seems highly unethical to say the least. But back to my original question. Is there anyway to create a secure or encrypted connection between 2 macs to get around Comcast's dirty tricks??
Re: Large Files Transfers on Comcast - shadow - 12-02-2007
[quote prof]Comcast advertises that they give you all this incredible speed but when you actually use it they throttle you for doing so. Seems highly unethical to say the least. But back to my original question. Is there anyway to create a secure or encrypted connection between 2 macs to get around Comcast's dirty tricks??
For large file transfers, ignore the whole "PowerBoost" thing. Your agreement with Comcast is most likely for 6 MB down, 768 kB up. This translates to sustained transfers of 768 kB per sec down and 96 kB per second up. Throw in protocol overhead and your are more likely to expect around 600 kB per sec down and 76 kB per second up.
Assuming a 5G file and a 100% dedicated channel, it should take about 19 hours to transfer. What estimated transfer times are you seeing?