[Tutor] OT: need computer advice from wise Tutors

Alan Gauld alan.gauld at btinternet.com
Tue Jun 29 17:11:12 CEST 2010

"David Hutto" <smokefloat at gmail.com> wrote

> > Or if the network is shared with other users or other applications
> So, the bandwidth supplied(better question for my own ISP) is like a
> drop cord, even with alleged T1 connections plugged in, it drop in
> accordance with usage that exceeds the max capacity even though they
> sell it as it's max capacity?.

It depends on the access mechanism. If its a T1 link then it is a
dedicated line for your own use and not shared by anyone - although
the server/router its connected to at the ISP may well be!

If its a typical ADSL line it will be conneced to a DSLAM at the
centeral office(by the telco) and  that will be shareed. So a typical
consumer line has a ratio of 50:1 users. A business line might be
only 10:1 or 20:1. This works on the assumption that most users
spend more time reading than downooading the content. As we
move to streaming data sources that assumption becomes invalid
and the DSLAM bandwidth is effectively shared.

ADSL also loses bandwidth the further you are from the office so what
is sold as an 8Mb line will rarely give more than 5-6Mb and may be
as low as 1 or 2. But that is mostly a physical limitation on the
copper cables used. And finally, the 'A' in ADSL stands for asymmetric
so the upload speed it usually only a fraction of the download speed,
often only a few hundred kilobits/sec. Even with ADSL+ (20M+) the
upload speed is usually less than 1Mb. That means that a 1MB(yte)
document may only take 1-2 sec to download but take 10s+ to
upload (why sending mail is usually much slower than receiving)

Alan G. 

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