Seems a little odd to me too... It may be that your DS3 is configured channelized and not clear, and their routing config will only alow one flow per channel at a time, effectively limiting the data rate of any single flow ot the capacity of a channel; problem with that theory being that a DS3 channel is generally one DS1, roughly 1.5mbit/s, and it makes no sense that they'd treat the DS3 as bundles of 3 DS1 channels...
I would open a ticket with the carrier, and ask for a specific technical document that explains what causes this per-flow bandwidth cap. I wouldn't expect actually getting the full 45mbit/s out of a full pipe T3, there is some overhead, but still 7mb is ridiculous.
If you want to paste back in that doco they provide (you'll probably have to escalate and press them consistently to get it), I'd be happy to review it and translate their network-guy-eese into english for you :)
Unfortunately, I suspect that if they had a pat answer all ready for you, many many many others have complained, this is probably a limitation of their network engineering in their cloud, and your only way to get around it may be another carrier.
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by: equalizerPosted on 2009-01-08 at 06:13:40ID: 23324958
DS3 technical specifications are below
Line rate: 44,736,000 b/s
Signals: 7 DS2 signals = 28 DS1 signals
Overhead bits:
56 bits total/frame
F-bits (framing) 28 bits/
M-bits (multiframing) 3 bits/
C-bits (stuffing) 21 bits
X-bits (message) 2 bits/
P-bits (parity) 2 bits/
in this calculation
LinkRate = 42.66 Mbit framed speed.
If you will calculate headers and footer bits for each frame, it will loose ~%4 for TCP/IP Troughput you can see max 40.8 Mbit/sec interface speed on DS3.
in addition, 1 file download never show 40Mbit speed you because of TCP protocol structure. Hosts are waiting acknowledment message for each segmet transfer. It is loosing time in this communication. You can put one side FTP server and other side you can download same file with flash get. You may almost catch real transfer speed. Real troughput test can make under real load.