Re: It's about wavelength as opposed to transceivers.
40Gbps was an OK interconnect for switches when there was nothing better, but it wasn't great for server connectivity when you were looking at upgrading from 10Gbps because you needed a little more bandwidth. Your 40Gbps costs per server were around 3x the costs of 10Gbps when you will probably only utilise 25-50%. in the medium term versus 25Gbps costs 2x 10Gbps and delivering 40-80%. of your bandwidth needs and providing a capable fibre channel competitor on the storage side.
AWS and Google have standardised on 25Gbps in their DC's already so it's likely the 25Gbps costs wil come down and 40Gbps will remain high.
Biting the hand that feeds IT
