/. Terabit Ethernet is Dead, for Now

Mon Oct 1 10:18:32 UTC 2012

On Mon, 1 Oct 2012, tom at ninjabadger.net wrote:

> If you can afford Wave Logic 3 interfaces for your Nortel^WCiena 6500's, 
> you'll find some pretty impressive things are actually possible, 
> including 100G per 100GHz guide over very large distances (think 
> Atlantic-large).

The amount of processing power and equipment in the transponder to achieve 
this is most likely out of scope for short term practical 400GE/1TBE that 
IEEE will put into standard.

So serial lights on/off much faster than 25 Gbaud runs into serious 
physical limitations, as some physical effects increase 4-fold when you 
on/off blink 2 times as fast. That's why we do not have 100Gbaud 100GE, 
but instead 4x25Gbaud.

> Coherence appears to be the secret sauce in pushing the SnR boundaries, 
> albeit I'm not going to pretend to even understand the physics involved, I 
> was just lucky enough to speak to some people that do. :)

Yes, for long-haul DWDM systems coherent detection is absolutely the way 
to go. For short and metro reach at low cost, that is probably going to be 
a bit further into the future.

-- 
Mikael Abrahamsson    email: swmike at swm.pp.se