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