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Testing for the MAXIMUM bandwidth

W

Werty

Senior member
was wondering how or whats the best way to test for the MAXIMUM bandwidth of my DSL.
im asking coz my plan, which is 2700kbps is just running at 2100-2200 MAX average. i called up my provider and ask why im just having these speeds when i could have gotten 2700kbps MAX as my plan stated. but they just gave excuses like that 2100-2200 was the average speed i can get for my plan, which i think is lame. even a 56K dialup can get its max at 7Kbps, mine can only go to about 270-300Kbps... im thinking that they are limiting my bandwidth to about 20% of total.

before when i had 1500kbps plan, i was averaging 1100-1200kbps on my tests, which is about 20% from my max. now that i have upgraded to 2700kbps, im only getting 2100-2200kbps, still about 20% from my max... do u think that my ISP is really limiting my bandwidth? do other ISP's do these? im RIGHT to complain and ask for my real MAX bandwidth, right? im kinda feel cheated if they are doin these....

 
no, you don't get full bandwidth from your ISP...speeds are theoretical maxes, but there is no SLA stating those speeds. Want to get "advertised" speeds? Have someone haul a T1 in, then you can complain if you can't max the pipe.


Part of the problem may be the other end (not enough upload pipe) or a router that is running slow somewhere between here and there, or any number of other issues beyond your ISP's control. You don't buy 2MB internet, you buy up to 2MB.


 
Originally posted by: wwolf226
yes.. i agree nweaver, the marketing 101 ploy.. bate'm, once hooked its too late.
Click to expand...

I do some part time stuff for a small wireless ISP. He did extensive testing before rolling out his plans, and his "800Kb/s" plan ranges between 600-1Mb, because he believes it's dishonest to sale what they won't have...
 
Well, you are probably getting 2700, you're just not using it all.

Jack's link does a good job of explaining it.
 
One thing to keep in mind is ISP's especially the big guys sell bit-rate not throughput.
Every protocol carries some overhead that eats up your bit-rate without throughput

Some examples.
ATM overhead is 8 bytes for every 54 transmitted (or about 15%)

If your data goes over any TDM circuit and does not exactly match the frame size of that protocol the empty space is just overhead....

T1 has a bit rate of 1.544 but framing bit overhead reduces that immediately to 1.536.

Overhead in TCP Frames are consistent but the smaller your packets the greater percentage of overhead in the transmission.
Large packets cause delays waiting for data to trensmit so throughput can go down there too.

TCP also uses a windowing concept which allows only a prediefined number of packets on the network without a reply. So the roundtrip time can also affect your throughput.

The larger the bandwidth the harder it is to test as very few devices can produce a single stream that fills the bandwidth of the pipe.
Try testing a 100MB ethernet connection. 🙂

The net is your never going to see a speed test provide the full bit-rate value as a throughput result.
80 % could be very reasonable depending on the technologies deployed by your providor.



 
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