Hi,

My ISP states that my Broadband connection is 2Mb, but how does this relate 
to time. i.e. How long would it take in theory to copy a 2Mb file up or down 
to the internet?

Thanks

Graham

On Mon, 23 Jan 2006 22:31:37 -0000, "Graham Naylor" 
wrote:

>My ISP states that my Broadband connection is 2Mb, but how does this relate 
>to time. i.e. How long would it take in theory to copy a 2Mb file up or down 
>to the internet?

Forgive me if I'm teaching a grandmother to suck eggs here, but here's
a simple answer to your question:

Your line is 2MBit/sec, which equates, roughly, to 200KBytes/sec. So a
200MB file will take, at maximum push, around 10-12 seconds to
download.

However:

It is very unlikely that you will get full bandwidth out of your line
because the other end feeding your information may well not be able to
feed it that fast, especially if it's feeding many others
simultaneously.

Also, it depends what sort of feed you're after. If it's an http file
transfer, or ftp or some other simple but fast mechanism, you may well
do quite well for speed.

If it's something like a bittorrent file, or some other peer-to-peer
fileshare, then you are very unlikely to get particularly good speeds,
especially if you allow your upload capacity to get saturated.

It's one of those "piece of string" questions, I'm afraid.

Quick answer: 10-12 seconds ideally, but that's rarely achieved.

Hope this helps!

Paul.

-- 
.. Bill Maher: "Tulips aren't flowers, they're gay onions"
.. A .sig is all well and good, but it's no substitute for a personality
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On Tue, 24 Jan 2006 08:04:30 +0000, Paul Harper 
    wrote:

> On Mon, 23 Jan 2006 22:31:37 -0000, "Graham Naylor" 
> wrote:
> 
>>My ISP states that my Broadband connection is 2Mb, but how does this relate 
>>to time. i.e. How long would it take in theory to copy a 2Mb file up or down 
>>to the internet?
> 
> Forgive me if I'm teaching a grandmother to suck eggs here, but here's
> a simple answer to your question:
> 
> Your line is 2MBit/sec, which equates, roughly, to 200KBytes/sec. So a
> 200MB file will take, at maximum push, around 10-12 seconds to
> download.
> 
> However:
> 
> It is very unlikely that you will get full bandwidth out of your line
> because the other end feeding your information may well not be able to
> feed it that fast, especially if it's feeding many others
> simultaneously.

Plus it is very unlikely that the upload (from computer to the net)
speed will be 2Mbps, thore connections cost a lot more.  It's more
likely to be 256kbps so the time to upload a file will be around 8 times
as long as to download it.

> Also, it depends what sort of feed you're after. If it's an http file
> transfer, or ftp or some other simple but fast mechanism, you may well
> do quite well for speed.
> 
> If it's something like a bittorrent file, or some other peer-to-peer
> fileshare, then you are very unlikely to get particularly good speeds,
> especially if you allow your upload capacity to get saturated.

Or even quite a few web sites, I frequently see download speeds of only
20KB/s (equivalent of 200kbps) on our work connection which is rated at
10Mbps, because the remote servers (and/or somewhere between them and
us) are overloaded.

> It's one of those "piece of string" questions, I'm afraid.

How Long Is A Piece Of String?  No, "How Long" is a Chinaman <g>...

Chris C

"Graham Naylor"  wrote in message 
news:dr3li6$vmd$1@newsg1.svr.pol.co.uk...
> Hi,
>
> My ISP states that my Broadband connection is 2Mb, but how does this 
> relate to time. i.e. How long would it take in theory to copy a 2Mb file 
> up or down to the internet?

Its actually quite easy - divide by 8.
So the perfect possible speed is 250K/s but the most ive got is say 240K/s 
due to imperfections on the line.

>
> Thanks
>
> Graham
>

On Thu, 26 Jan 2006 12:48:12 -0000, Gutz 
    wrote:

> "Graham Naylor"  wrote in message 
> news:dr3li6$vmd$1@newsg1.svr.pol.co.uk...
>> Hi,
>>
>> My ISP states that my Broadband connection is 2Mb, but how does this 
>> relate to time. i.e. How long would it take in theory to copy a 2Mb file 
>> up or down to the internet?
> 
> Its actually quite easy - divide by 8.
> So the perfect possible speed is 250K/s but the most ive got is say 240K/s 
> due to imperfections on the line.

Actually, no, because you aren't taking into account the protocol
overheads.  40 bytes per packet fot a TCP/IP header with a maximum
packet size of 1500 bytes is around 3% minimum, and that accounts for
most of your speed difference.  That's assuming no other overheads and
delays, like at the start and end of the transfer.  As well as the
bandwidth available to the remote site, some don't get anywhere near
250kbps when they are heavily loaded...

Chris C

"Chris Croughton"  wrote in message 
news:slrndtif5g.rif.chris@ccserver.keris.net...
> On Thu, 26 Jan 2006 12:48:12 -0000, Gutz
>    wrote:
>
>> "Graham Naylor"  wrote in message
>> news:dr3li6$vmd$1@newsg1.svr.pol.co.uk...
>>> Hi,
>>>
>>> My ISP states that my Broadband connection is 2Mb, but how does this
>>> relate to time. i.e. How long would it take in theory to copy a 2Mb file
>>> up or down to the internet?
>>
>> Its actually quite easy - divide by 8.
>> So the perfect possible speed is 250K/s but the most ive got is say 
>> 240K/s
>> due to imperfections on the line.
>
> Actually, no, because you aren't taking into account the protocol
> overheads.  40 bytes per packet fot a TCP/IP header with a maximum
> packet size of 1500 bytes is around 3% minimum, and that accounts for
> most of your speed difference.  That's assuming no other overheads and
> delays, like at the start and end of the transfer.  As well as the
> bandwidth available to the remote site, some don't get anywhere near
> 250kbps when they are heavily loaded...

Ok... so its 248.32Kbps minus 'imperfections on the line' i.e. random delays 
:P

I think I've had just over 240 from some major UK based site at an off-peak 
GMT time .. When I say i've never had 248 I mean over a 3 year period using 
lots of different clients and web sites.
I use bit-torrent a lot and it seems to cap it at 220 with its obscene 
overheads :s

>
> Chris C

Can I add a question here - assuming that 8MB and higher speeds become
available, but that our upload rates stay at 256kb/s, what kind of cap
would that put on maximum download speeds.

I assume that for each <insert amount here> of data that comes DOWN my
line, my PC sends some kind of acknowledgement back? So if I can only
send them back at 256kb/s, is that ever going to limit the down speed?

-- 
Bryan Anderson

"Bryan Anderson"  wrote in message 
news:a54tt1pv558tivk5c3h5f5qjrlgh53bntg@4ax.com...
>
> Can I add a question here - assuming that 8MB and higher speeds become
> available, but that our upload rates stay at 256kb/s, what kind of cap
> would that put on maximum download speeds.
>
> I assume that for each <insert amount here> of data that comes DOWN my
> line, my PC sends some kind of acknowledgement back? So if I can only
> send them back at 256kb/s, is that ever going to limit the down speed?

You should be fine with 256k/s - I dont know the maths behind it but i think 
its something like 5k/s upstream for 2Mb which equates to say 64KB upstream 
required.

Eventually TCP-6 will come out and as you'll be sending packets constantly 
and the upstream requirements will go up but its not something to worry 
about.

>
> -- 
> Bryan Anderson