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Old 07-13-2009, 11:26 AM   #1
mq15
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Question What does it mean by the Bandwidth of a link/connection/netwrok?


Hello Friends,
I have come to know that:
Quote:
The bandwidth is the information carrying capacity of a link, connection or the network
through a book of networking.

But I want to clear the concept. I mean how it's measured? What is the difference if it is low or high? And how can I find what is the bandwidth of my DSL connection? etc etc...

Please guide me.

Regards
 
Old 07-13-2009, 12:21 PM   #2
catkin
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Hello mq15

See http://pcsupport.about.com/od/termsb/g/bandwidth.htm for an explanation and a link to sites you can use to measure your own connection.

What it doesn't stress there is that bandwidth is measured in bits per second (bps) not bytes per second (Bps). A byte is 8 bits; by the time communications overheads are added on it takes ~10 bits to transmit a byte so you can roughly divide the bps by 10 to get Bps which gives a better guide to how long it will take to transfer a file because file sizes are most commonly given in bytes.

Best

Charles
 
Old 07-13-2009, 12:27 PM   #3
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From The Free Dicitionary article at:
http://www.thefreedictionary.com/dic...Word=bandwidth

Quote:
The term bandwidth is also loosely used to refer to the rate at which data can be transmitted over a given communications circuit. In the latter usage, bandwidth is usually expressed in either kilobits per second or megabits per second.
That is to say "high" or "low" is relative. 38800 baud (bits per second) modems at one point was "high" bandwidth compared to 1200 baud. Now 38800 baud would make most people gnash their teeth and pull their hair out. Nowadays when one talks about "broadband" in home computing they mean high speed (high bandwidth) as compared to dial-up speeds. However those "broadband" bandwidths might be tiny compared to a dedicated T1 or T3 circuit or your in house Gigabit network at the office.
 
Old 07-14-2009, 08:50 AM   #4
mq15
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Thanks a lot both of you.
I performed a test at: http://pcsupport.about.com/od/termsb/g/bandwidth.htm
The download speed comes out to be 0.71 Mb/s and Upload speed comes out to be 0.18 Mb/s. But my ISP claimed that it gives
1 Mb/s of bandwidth to its customers. Is it a contradiction or what ?
 
Old 07-14-2009, 10:47 AM   #5
catkin
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Hello mq15

I don't fully understand but, if you add 0.71 and 0.18 it's not so far from 1.0 at 0.89 Mbps. The link itself may be running at 1.0 Mbps with the discrepancy caused by communications overheads -- error checks, framing, control data ...

Also, unless you have paid for a very good connection, most ISPs don't actually guarantee bps figures. To keep costs down, ISPs bundle multiple users together on a channel that can't support them all at full speed at the same time. As long as all the customers aren't trying to use full speed at the same time it works out OK. The jargon is "contention ratio". It can be a problem if you're unlucky enough to be sharing with a lot of P2P users.

Best

Charles
 
Old 07-20-2009, 08:51 AM   #6
mq15
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Thanks catkin but whenever I download something, the download speed is never more than 120 Kb/s in fedora and never more than only 12Kb/s in vista (regular downloads in both OSs, not with download accelerator applications etc). Does this means that I am not taking the benefits of even 0.71 Mb/s of bandiwdth that I am getting according to the test at : http://pcsupport.about.com/od/termsb/g/bandwidth.htm?
 
Old 07-20-2009, 09:18 AM   #7
catkin
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Hello mq15

Dunno about Vista; it seems to be broken in many respects.

The download speed you have seen might be limited by the site(s) you are downloading from or somewhere else along the way -- there are many links in the network from the download server(s) to you.

You could try downloading from other sites. Sorry -- I cant think of any that are surely fast. If you are set up to torrent, you could try downloading a Linux files such as OOo_3.1.0_LinuxIntel_install_en-US_deb.tar.gz. They usually have many seeds so max out your connection.

Best

Charles
 
  


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