ADSL Bandwidth Monitoring

[Tim Daneliuk]

RW wrote:
> On Sat, 08 Sep 2007 15:27:38 -0500
> Tim Daneliuk <tundra at tundraware.com> wrote:
> 
>> Amitabh Kant wrote:
>>> On 9/8/07, Bahman M. <b.movaqar at adempiere.org> wrote:
>>>> I tested the connection by downloading 2~3 files simultaneously
>>>> and used 'bmon' as Mel suggested in another reply (thanks to
>>>> him).  As I'd already guessed the RX don't get bigger than 30~40%
>>>> of the expected bandwidth.  I performed the test with some other
>>>> files and there was no difference.
>>>>
>>>> Thanks,
>>>>
>>>> Bahman
>>> The bandwidth being advertised by your ISP would be the maximum
>>> thoughput allowed on your DSL lines with multiple DSL users sharing
>>> the same bandwidth, something that is generally known as contention
>>> ratio.
>>>
>>> See this link:
>>> http://en.wikipedia.org/wiki/Contention_ratio
>>>
>>> Amitabh
>> But you should be able to hit the advertised bandwidth.  To the best
>> of my knowledge, DSL itself is NOT a shared medium.  It is a point-to-
>> point technology from your premise to the Central Office.  The
>> bandwidth *behind* the CO may be shared, but should be so large
>> as to not be a bottleneck.   
> 
> It depends on your circumstances. Some people are constrained by
> contention ratio some aren't. Some ISPs offer a better ratio for a
> more expensive accounts.

I don't understand this.  If the actual DSL circuit is point-to-point -
i.e., not shared between the premise and the DSLAM in the CO, just
exactly *where* is the contention occuring?  I would think (and could
be wrong) that the only other place would be in the bandwidth behind
the DSLAM - the actual phone network.  But this is typically very,
very high capacity stuff, at least here in the US, and I sort of doubt
it couldn't deliver the stated bandwidth.

Not arguing here, just wondering...

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Tim Daneliuk     tundra at tundraware.com
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