Le 2012-02-03 04:22, Invisible a écrit :
>> I have absolutely never
>> had to use the $ key on my keyboard, unless I was programming in Perl.
>
> This comment makes the whole discussion worth it! :-D
>
>>>> "In another building" DOES NOT mean "over the Internet". Private data
>>>> circuits predate the internet, and no company would use the Internet to
>>>> link two data centres together.
>>>
>>> How is that even *possible*? It's not like you can just go to the
>>> hardware store and buy 25km of copper wire and then put it into the
>>> ground with a shovel on your day off or something...
>>
>> You don't do it yourself, unless you are in a campus environment and can
>> easily rip up the parking lot and lay down your own fibre or copper.
>>
>> Step 1. Call your telco rep and order a circuit between site A and
>> site A.
>> Step 2. Telco will forward the request to a planner who will determine
>> if the existing cabling between both sites and central offices (CO) has
>> enough available bandwidth.
>> Step 3a. If not, the planner will forward the request to their
>> infrastructure group who will get diging permits from the
>> city/county/whatever and lay down new bundles of cables.
>> Step 3b. If the answer is yes, or once the new cables have been laid,
>> the telco planner will forward your request to an enabler who will
>> configure the CO switches to map the circuit from Site A's demarcation
>> point to Site B's demarcation point.
>> Step 4. Technicians will come on site, at both locations, and terminate
>> the circuit from their demarc point to the exact rack you ask them to.
>> Step 5. You plug in the circuit in your equipment (router, switch, or
>> mainframe front-end-processor, to name a few)
>>
>> Tada!
>>
>> Usually, all of this is done for a small nominal fee. Any work they have
>> to do between demarc points will be undertaken at their own expense,
>> which they will recoup on your monthly usage bill, of course.
>>
>> By the way, if you ordered an "internet" link, the exact same steps
>> would have to take place, except that they would be duplicated for site
>> A to ISP and ISP to site B, and then the ISP would add its own routers
>> at both ends and charge you twice as much and more for the "managed
>> services".
>
> Think is, if you order an Internet link, the telco has to run a few
> hundred yards of cable to the nearest junction box at one end, and a few
> hundred yards at the other end.

Which is exactly what I have described above, except the dealing with 
the telco is done by the ISP's engineers, not you.

> If you want a dedicated circuit from one
> end to the other without going via the Internet, they have to run
> several miles of cable just for you. Who the /hell/ can afford that? o_O
>

No. No. No. No.  What makes you think they would have to lay more cable 
for a dedicated circuit than for an internet connection?  Re-read step 2.

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.

An Internet VPN goes:

Site A -> Telco CO 1 -> Telco Cloud -> Telco CO 3 -> ISP -> Telco CO 3 
-> Telco Cloud -> Telco CO 2 -> Site B.

Now, can you see that connecting to an ISP is effectively ordering TWO 
dedicated circuits instead of one?

Using an Internet VPN only makes sense when the costs of a dedicated 
cricuits becomes prohibitive and you must share the cost with others, at 
the expense of latency and garanteed bandwidth.

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