/. Terabit Ethernet is Dead, for Now

Masataka Ohta mohta at necom830.hpcl.titech.ac.jp
Mon Oct 1 12:01:30 UTC 2012


tom at ninjabadger.net wrote:

>> It depends on distance between senders and receivers.
>>
>> However, at certain distance it becomes impossible to use
>> efficient (w.r.t. bits per symbol) encoding, because of
>> noise of repeated EDFA amplification.
> 
> <500km not enough?
> 
> https://www.de-cix.net/news-events/latest-news/news/article/de-cix-chooses-adva-optical-networkings-100g-metro-solution/ 

As it says:

	ADVA Optical Networking's 100G Metro solution is built on
	4x28G direct detection technology

and I wrote:

	Still, for 100GE, under some circumstances, 100GE with 4*25G may
	become less expensive than 10*10GE.

100GE over 500km could be fine.

>> For 50Gbps lane, it becomes even harder and, for 100Gbps lane,
>> it will likely to be impossible.
> 
> Tell this to Ciena... ;)
> 
> 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).

I'm afraid it uses 8 or 4 lanes.

> Coherence appears to be the secret sauce in pushing the SnR boundaries,

Just +3db, which is already counted, nothing more than that.

>> http://www.peering-forum.eu/assets/presentations2012/JunpierEPF7.pdf
>>
>> But, it does not say much about >100G.
> 
> Yes, that is the one. Slide #11 is the one I'm referring to, 'Projection 
> of Form Factor Evolution to 400G', which is relevant to the discussion 
> on optic densities and the push above 100G.

As I wrote from the beginning that:

	(if same plug and cable are used both for 100GE and 10*10GE).

physical form factors can be identical between 100GE (10*10G) and
10*10GE.

Thus, the point of the slide #11 is not a valid counter argument
against my point that trunked 40*10GE or 16*25GE is no worse than
actually trunked 400GE with 40*10G or 16*25G.

While slide #12 mentions 50Gbps per lane, it is too often impossible
to be as practical as the Ethernet today.

						Masataka Ohta



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