Le 2012-02-03 09:49, Invisible a écrit :
>> What makes you think they would have to lay more cable
>> for a dedicated circuit than for an internet connection?
>
> The fact that rather than connecting you to an existing circuit, they're
> building a brand new one from scratch.

I never said they would build a new one from scratch, unless there was 
no bandwidth available on their existing infrastructure.

>
>> A dedicated circuit from my company's site A to site B goes:
>>
>> Site A -> Telco CO 1 -> Telco Cloud -> Telco CO 2 -> Site B.
>
> If it goes through their main cloud, it isn't a dedicated circuit. It's
> a shared circuit.

You can have dedicated bandwidth allocated to you on a shared physical 
circuit.  For example, on a DWDM link, if I assing the 720nm frequency 
to you, and the 680nm frequency to me, we would both have dedicated 
bandwidth on that fibre strand as it is physically impossible for our 
signals to suddenly merge or impact the other.  Likewise for TDM 
circuits, where each fram is divided into timeslots, and each customer 
is allocated a certain amount of timeslots.  There is no possibility of 
overlap or oversubscription.

A "shared" bandwdith scenario would be ATM, Frame-Relay SVCs, X.25, 
etc... where packets are sent through the cloud on a 
first-come-first-serve basis and where there is the possibility of 
oversubscription.

I apologize for using the word dedicated, instead of point-to-point.
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