Post B6zf9FJHfg3xO1bgLQ by azonenberg@ioc.exchange
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 (DIR) Post #B6zf9FJHfg3xO1bgLQ by azonenberg@ioc.exchange
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       Cursed networking things I recently learned:1) There are two, mutually incompatible, standards for running 40GbE over a single multimode fiber pair.One uses CWDM with four wavelengths (850/880/910/940 nm) mapping each 10G serdes lane to a wavelength. This also supports 100G.The other uses only two wavelengths (850 and 900), gearboxing two serdes lanes onto each, with an optical data rate of 20 Gbps per wavelength. Since the lasers/gearboxes can't run at 50 Gbps NRZ it won't support 100G.Of course, I have some QSFPs of each type.2) Mellanox ConnectX6 NICs normally aren't picky about optic vendor codes.The one exception is dual speed 40/100G optics. They'll happily run anybody's dual speed optic at 100G, or a single speed generic 40G optic at 40G. But if you want to run a dual speed one at 40G it needs to be Mellanox branded for some reason.