Re:25 Gigabit Linux internet router PC build
by oasisbob on Sunday July 11, 2021 @12:43PM
(#27802376)
I'm being a bit glib, but from the point of view of someone who used SFP optics once in a while, it seemed like the whole "standard" was a bit of a mess.
If it was known that vendors would try to push their thermals past what the device cage would support, why not address that better?
The general impression I was given is that thermal loads were one of the primary reasons given for vendor-locking pluggable optics, and that the original SFP spec didn't even address it.
Which is also why plugging a large amount of DWDM optics into a datacenter switch is a bad idea. Datacenter switches are _not_ designed with this in mind. You run into risks of both overheating the switch as well as overloading the PSUs. A small number of high-power optics ain't gonna break the switch though.
And: 10Gbase-T SFPs have horrendous power consumption, even worse than DWDM SFPs. At these speeds, the signal over copper is mostly mush, and the PHY contains a none-too-trivial analog & digital signal processor. Which, again, is where limitations for 10Gbase-T SFP usage come from. If at all possible, avoid this shit — there's absolutely no reason to have 10Gbase-T inside a rack, for example. Just use DAC cables or SR optics.