/. Terabit Ethernet is Dead, for Now

Tom Hill tom at ninjabadger.net
Sun Sep 30 22:49:16 UTC 2012


On 30/09/12 20:05, Jimmy Hess wrote:
> On 9/29/12, Masataka Ohta<mohta at necom830.hpcl.titech.ac.jp>  wrote:
>> >Jared Mauch wrote:
> ...
>> >The problem is that physical layer of 100GE (with 10*10G) and
>> >10*10GE are identical (if same plug and cable are used both for
>> >100GE and 10*10GE).

> Interesting.    Well,  I would say if there are no technical
> improvements that will significantly improve performance over the best
> possible carrier Ethernet bonding implementation and   no cost savings
> at the physical layer  over picking the higher data rate physical
> layer standard,_after_    considering  the increased hardware costs
> due to newly manufactured components for a standard that is just
> newer.
>
> E.g.  If no fewer transceivers and fewer strands of fiber required,
> or  shorter wavelength required,  so it doesn't enable you to achieve
> greater throughput over the same amount of light spectrum on your
> cabling, and therefore lower cost at sufficient density,   then:  in
> that case, there will probably be fairly little point in  having the
> higher rate standard exist in the first place,   as long as the
> bonding mechanisms available are good  for the previous standard.

When you consider 100GBASE-LR4 (with its 4x25G form factor) there is 
some efficiency to be gained. ADVA & others now support the running of 
each channel on their DWDM muxes at ~28G, to suit carrying 100GBASE-LR4 
over four of your existing waves. CFPs with 4xSFP+ tunable optics in the 
front are out there for this reason.

Once you get your head (and wallet) around that, there becomes a case 
for running each of your waves at 2.5x the rate they're employed at now. 
The remaining question is then to decide if that's cheaper than running 
more fibre.

Still a hard one to justify though, I agree.

I've recently seen a presentation from EPF** (by Juniper) that was 
*very* interesting in the >100G race, from a technical perspective. Well 
worth hunting that one down if you can, as it details a lot about optic 
composition in future standards, optic densities/backplanes, etc.

Tom

** I couldn't justify going, but the nerd porn is hard to turn down. :)



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