What is the maximum internet bandwidth a single computer can utilize?

[Epsil0n00]

At work we just hooked up a secondary internet connection (our primary is a T1 with nice upload, but weak download ratings). We got a 7Mb/1Mb DSL line from Qwest. After it was connected, before connecting it to the rest of our LAN, I hooked it up to one laptop and ran some speed tests. Over several days, at varying times of day, using different test sites the laptop always averaged around 1.5Mbps up and 550Kbps down. I tried it out on my desktop (connected via the LAN with gigabit switching) and I consistently got 4.5 to 5.0 Mbps down. This is much less than the 7Mb that we are paying for.... so I called Qwest out to check things out.

Qwest guy came today and tested our termination that they installed, tested the router, tested the line from their termination to our LAN hookup... everything looked perfect. The router even indicates that it is connecting at 7Mb X 1Mb. His testing equipment was all recognizing the correct speed provisioning. However, he hooked up his laptop and got the same results that I was getting. He then moved the router and hooked it up directly to the termination point (to eliminate any possible wiring problems on our site) and got the exact same results.

Now they have come back and said that a single computer is unable to take full advantage of the 7Mb connection because at that high of a speed the internet testing would be limited by the internal bus speed on the mobo instead of the DSL connection. Is this true?! They said that the most accurate way to test it would be to hook up several computers to the DSL and have them all download the same file and see what the combined download bandwidth is (because a single PC would always be limited by its internal bus speed and therefore give an inacurate internet speed rating). I have to admit that this would help to explain why all the laptops I tested were much slower than my desktop (because the laptops have a slower bus speed on their mobos than my desktop).

Is there any legitimacy to this explaination? Can anyone provide any other information that could help me understand this odd situation?

If it is true that the bus speed on the motherboard is limiting the internet connection speed, won't that cause problems as Comcast and other broadband providers near speeds of 7Mbps and above? I currently have a 4Mb connection with Comcast at home and my PC always tests right around 4Mb... at what point will my computer become the bottleneck?

Thanks for any perspective you have!
Epsil0n

 

[randal]

It won't. Your PC is not the bottleneck, the rest of the internet is. Your PC is (disregarding things like HD speed) capable of saturating a 100mbps link, so 7mbps is a drop in the bucket. Think about it -- your PCI bus is probably running at 33mhz and is 32bit. 33*32 = 1056mbps (~125MB/sec) ... sure, there are other things on the bus, but 7mbps is LOT less than 1,000+.

The slowdowns are the rest of the internet; you may be downloading from a server that doesn't have 7mbps of upload to match your 7mbps of download. Many bandwidth-checking sites top out at 5mbps or so as well. The only real way to try and saturate your link is to get several PCs on the DSL line and go out and hammer the crap out of it by downloading huge files from gigantic servers (think Linux or FreeBSD CD Images).

The Qwest guy was right in that it will be tough for a single computer to saturate your 7mbps, simply because one person cannot generally connect to enough internet sites at once to fully utilize. Your bus speed does NOT slow things down in any way, shape or form; I've personally seen lowly 486s handle upwards of 40mbps of traffic without issue. Several users, all powersurfing/downloading, may be able to saturate your link. Honestly though, 7mbps is a lot of downstream bandwidth.

$.02
randal

 

[Epsil0n00]

Randal, You have a good point. I should have thought about this more and realized that of course an individual PC can handle more than 7Mbps transfer rate... it happens all the time on our LAN. In fact, just today I imaged a computer and it sustained a transfer rate of 190MB/minute for a long time. If I calculate that correctly 190MB/Min is roughly equal to 3.15 MB/sec, which is 25.2 Megabits/sec... which is way more than 7Mbps.

I will have to gather a test lab of computers and have them download some big files all at once and see what happens! Any ideas why all the laptops I tested would operate at about half the speed of the desktops that I tested in the same manner?

Thanks!
Epsil0n

 

[Zugzwang152]

I suggest downloading large files from ATI, NVIDIA or Microsoft. Road Runner recently upped my down speed to 5Mbps and these were the only sites where I could utilize my full potential of around 600-650KB/s.

Downloading the DirectX 9.0c redist or full SP2 installer would be good tests. I have yet to see a connection that Microsoft cannot saturate.

 

[freegeeks]

that Qwest dude is giving you false information. I did some dowloading on a 10Mb Vdsl line at work and I can easily saturate the link by opening multiple ftp connections to different servers, the same on our 34Mb internet connection. I have to transfer big files on our LAN on a daily basis and I can reach up to 160Mb doing a ftp transfer between 2 servers with Gigabit ethernet interfaces

There could be another problem in your case, even when the router is syncronising at 7Mb there could be some bottleneck on the port on the DSLAM (wrong configured cross connect, wrong shaping). A 2nd possibility is the ATM PVC going from the DSLAM to the BAS (Broadband Access Server). These links are overbooked and it is possible that the VP is full. You can check this by doing some download tests at night (when there is less traffic), if the download is OK then you are almost sure that the bottleneck is somewhere on the backbone network of your provider

good luck

 

[spidey07]

I've found those speed test sites to be very unreliable and inaccurate.

downloading from MS is a decent test.

 

[Nothinman]

I suggest downloading large files from ATI, NVIDIA or Microsoft. Road Runner recently upped my down speed to 5Mbps and these were the only sites where I could utilize my full potential of around 600-650KB/s.

I consistently get those kinds of speeds from just about every Debian mirror I try too.

 

[jamesbond007]

I bet that line could be saturated pretty fast if you opened up a few connections to download WinXPSP2 from Microsoft/Conxion servers.

 

[lapierrem]

if it has only a 10BaseT or a wireless b connection off a wireless router, what they are saying might be true.

 

[Epsil0n00]

I opened up several connections today and downloaded a bunch of stuff. I downloaded 2 copies of XP-SP2, the UT2004 demo and the UT2004 server files all at once. On my one computer I got a combined average of about 5.2 to 5.4Mb/s (about 675 KB/s, which is pretty smokin'). This is similar to what the speed tests indicated previously.

Next week I will try downloading a bunch of information from several download sites, on several computers at once and see what the combined bandwidth between all those simultaneous downloads is.

Thanks for all the feedback--I'll keep you posted on my findings.
Epsil0n