On 30/09/12 20:05, Jimmy Hess wrote:
On 9/29/12, Masataka Ohta<mo...@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. :)