Technical relationship between connection and download speeds

[techtata]

Hi,Is there any scientific/technical theory that defines the relationship between connection speed and download speed? For example if one is having an internet connection of 1 Mbps speed and he is likely to get a download speed of say 60-70 kbps while downloading a file/movie etc. from the net. Or in other words the same person might have to wait for 85 seconds to download a file worth 5 MB thereby giving him an approximate download speed of 60 kbps.My friends in the US and UK having connection speeds of 10 Mbps get an average download speed of 225-250 kbps. Thanks.

 

[mgcarley]

You're talking about converting kilobits/megabits to kilobytes/megabytes. This gets confusing because they're both usually abbreviated as kbps/mbps and kBps/mBps (capitalization of the "B" is technically required to differentiate the two measurements).The simple answer is to divide by 8, so 1024 kbit/s becomes 128kbyte/s.Of course, what you actually get from your connection as far as throughput is concerned is very much up to individual circumstances. It is a best effort service (meaning, they'll do their best but they won't guarantee you a particular speed), so what you'll get depends heavily on the quality of the copper line, type of modem (sometimes), distance from exchange/cabinet/dslam, congestion, contention, the CSR/CBR (constant stream/bit rate) implemented by the telco (in NZ it is 45kbit/s per subscriber averaged over 15 minutes) and any number of other things which may or may not be in your control - even which server you're downloading from (some restrict individual streams to a certain bit-rate, so no matter how fast your internet connection is, you will get a certain maximum speed as determined by the admin of that particular server)...So you *should* in theory get about 90kbyte/s from your 1mbit/s connection and your friends in the USA and UK if they are on lines that are synchronized at 10mbit/s (adsl synchs at whatever it can get, not any particular speed), so they should typically be able to attain nearly 1mbyte/s.I'm right now on an ADSL2+ line which has a theoretical maximum of 24mbit/s, but the line synchs at around 16mbit/s, so I get about 1.3-1.4mbyte/s when I'm downloading (depending on what, from where and when, of course)... I might attain these kinds of speeds with a download coming from a server in NZ or Australia, but from a server in the USA I can expect to receive only about 600kbyte/s anyway: this isn't really anything I can control and my ISP probably can't either, since the slowdown would seem to occur on the link between NZ and the USA (or Australia and the USA, sometimes) which is not physically controlled by my ISP, ergo...

 

[auroraPWN]

Mgcarley has clearly answered your query but i will simplify the above answer for a layman .

Connection speed : This speed is mostly mentioned in xkbps OR xmbps ( Where x stands for the speed )
Ex. 2mbps . small "b" stands for bits

Now the technical conversion is 1mbps = 1024kbps ; What does the capital "B" signify ? stands for bytes

8 bits = 1 byte or 8bits=1Byte . Simply divide the value of speed quoted to you by "8" and you shall get the speed in kBps ( The speed you actually notice while downloading )

2mbps=2048kbps=256kBps.


Now as far as the attainable speed goes this is generally equivalent OR greater than 80% of your mentioned connection speed. ( This factor depends on many things like line quality , distance from exchange , ISP server traffic in that area etc.. )

so for a 2mbps plan you should get 256kBps x 0.8 = 205kBps

 

[mgcarley]

Mgcarley has clearly answered your query but i will simplify the above answer for a layman .

Connection speed : This speed is mostly mentioned in xkbps OR xmbps ( Where x stands for the speed )
Ex. 2mbps . small "b" stands for bits

Now the technical conversion is 1mbps = 1024kbps ; What does the capital "B" signify ? stands for bytes

8 bits = 1 byte or 8bits=1Byte . Simply divide the value of speed quoted to you by "8" and you shall get the speed in kBps ( The speed you actually notice while downloading )

2mbps=2048kbps=256kBps.


Now as far as the attainable speed goes this is generally equivalent OR greater than 80% of your mentioned connection speed. ( This factor depends on many things like line quality , distance from exchange , ISP server traffic in that area etc.. )

so for a 2mbps plan you should get 256kBps x 0.8 = 205kBps

LOL. This is why I choose to write kbit/s kbyte/s and mbit/s mbyte/s - there's no clarification needed as to what I'm referring to. To make matters worse, the storage industry uses base10 to calculate the room on your hard drive, whereas the actual unit of storage is measured in base2 - so 1 trillion bytes comes out to about 936GB.

The 80% rule isn't really measurable or particularly reliable - what you're talking about is TCP overheads which aren't measured in percentages.

Like I said in my post, the simple answer is to divide by 8, so 1mbit/s = 128kbyte/s. Take in to account some environmental factors and aforementioned overheads and you should get a bit less than that (120 on a high quality line, less depending on packet retransmissions and whatnot).

 

[techtata]

Like I said in my post, the simple answer is to divide by 8, so 1mbit/s = 128kbyte/s. Take in to account some environmental factors and aforementioned overheads and you should get a bit less than that (120 on a high quality line, less depending on packet retransmissions and whatnot).

Thanks a lot, it makes sense to me now. Thanks a lot again to both of you gentlemen for taking the time to write in such great detail, appreciated...

---------- Post added at 04:07 PM ---------- Previous post was at 03:46 PM ----------

Here what tried few months ago, thanks

https://broadband.forum/broadband-in-india/59824-1-gb-download-34-mins/