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Old 12-08-2010, 02:11 PM
Lamar Owen
 
Default Asymmetric connections (was: IPV4 is nearly depleted, are you ready for IPV6?)

On Tuesday, December 07, 2010 10:37:02 pm Christopher Chan wrote:
> On Wednesday, December 08, 2010 03:11 AM, Ben McGinnes wrote:
> > The even more horrendous problem, which is so pervasive it affects
> > everyone, is the insistence on asymmetric connections. Even when
> > Australia does get this fabled fibre-to-the-home, it still won't be
> > symmetric. *sigh*
> >
>
> Fibre connections that are not symmetric...sure going out of the way that.

Not really, once you realize that more optical power is required for greater bandwidths at the same distance. It is rather safer and less expensive at the CPE to have a broad receiver and a narrow transmitter. Fiber still obeys power density rules. Not to mention that passive splitting of the downstream and driving with high power lasers couple with either Raman or Erbium-doped fiber amplifiers saves money for the carrier.

And there is of course single fiber RX/TX muxing, where the upstream is DWDM on a 1550nm window wave at a low power, and the downstream is a high power 1310nm single wave, or CWDM even. Running a dedicated fiber pair to each customer is expensive; CATV fiber supertrunk digital systems are well-tested at high (>+30dBm optical) powers and are much less expensive for the carrier, meaning they are much less expensive for the subscriber, too. Even if they *are* oversubscribed.

While it is easy to believe in an 'asymmetric/no servers/ I got all the content/ mwahahaha!' conspiracy, simple economics and physics explain most of the reasons that oversubscribed high bandwidth downstream coupled with less oversubscribed low bandwidth upstream is the norm for consumer links. Even fiber.

Or would you prefer paying kilobucks per month for a tariffed OC3/12/48 or Gigabit provisioned Metro E? (that's all I can get, and it does cost kilobucks to get it).
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