Manawyrm | Sarah1d ago

Just patched a long fiber link, which would've absolutely _sucked_ to get CAT.7 cable through.
The steel-armored OS2 cable is cheap and super robust/easy to work with. The LC connectors are even smaller than the hole for CAT.7 would've been.

This is nice \o/

What I want to say is: Don't be afraid of fiber for DIY networking people, it's awesome and often muuuch better than copper cable!

I also didn't have to do any annoying LSA+ terminations or crimps and the link will do 10G+ easily :)

Show threadanne.💫
@manawyrm I've been curious about trying this once I actually make a permanent cable run to my tinker shop...what equipment did you use for either end of the cable? :)
Mar 24 at 10:29amWeb
Show threadManawyrm | Sarah1d ago

@ann3nova

No-name china 1270nm/1330nm SMF BiDi SFP transceivers (12$ on Amazon)

One side is my regular big Ethernet switch, which already had some SFP ports.
The other side is a TP-Link SFP media converter (also 15$).

Show threadanne.💫1d ago
@manawyrm Heck yeah. I'm already making a list...thank you. :)
Show threadMarcus Müller1d ago
@ann3nova @manawyrm also note that used PCIe 10GBase-X cards for SFP+ transceivers have gotten really cheap (data center equipment that is getting old and thus thrown out)
Show threadhcsch1d ago
@manawyrm @ann3nova do you need attenuators if you have an especially short run of cable between transceivers or can they just deal with ~full tx power arriving at their rx port?
Unless I fumbled 100m of an OS2 cable (assuming 0.4dB/1km) with LC/APC connectors (assuming 0.2dB insertion loss) at both ends only attenuates to about 90% of the input power
Show threadManawyrm | Sarah1d ago

@hcsch @ann3nova
They can deal with it.

This is well specified in the datasheet of the transceivers:
https://resource.fs.com/mall/resource/sfp-1g34-bx10-datasheet-20251208090113.pdf

Average Output Power POUT: -9 to -3 dBm
Input Saturation Power P(SAT): -3 dBm
Receiver Damage Threshold: +3 dBm

So yeah, in other words: No problem, even a direct no-loss 10cm link would be (barely) in spec.

Show threadhcsch1d ago

@manawyrm @ann3nova neat, I wasn't quite sure how close you can get to the saturating power, but I guess I could've just assumed that it'd be fine since they specced it to fit barely for zero-loss (which you wouldn't really get anyways).

Thanks ^^

Show threadMarcus Müller1d ago
@manawyrm @ann3nova hey, because energy for a year can quickly become more expensive than the hardware: do you happen to have a wall-power measurement for the media converter? (just an order of magnitude, not something detailed. I want to know whether we're talking 4€/a in electricity, or 50€/a.
Show threadManawyrm | Sarah1d ago

@funkylab @ann3nova
Mine's a TP-Link MC220 and it draws 1.3W from the wall (with an active 1000MBit/s link), including the SFP module.

So yeah, 4 Euro/Year sounds about right.

Show threadMarcus Müller1d ago
@manawyrm @ann3nova nice, that's super helpful!
Show threadManawyrm | Sarah1d ago
@funkylab @ann3nova Seeing (and thinking about) this number made me realize why I like my solar setup soo much... 😆
Show threadMarcus Müller1d ago
@manawyrm @ann3nova yeah, used to be that that 1 W·a = 3€, now we're a bit above that, still a useful rule of thumb to estimate OPEX when "just" adding another fridge, heater, electric hamster or server to your zoo of devices.
Show thread~n1d ago
@funkylab @manawyrm @ann3nova If you have SFP+ anyway, surprisingly the power draw is much higher for copper. 10GBaseT sucks about 2-3W while even an LR 10G optic will often consume less than one Watt.
(also something to be mindful of in high-density applications, the dissipated head adds up more than one would think)
Show threadMarcus Müller1d ago
@nblr @manawyrm @ann3nova yeah, I mean, my workstation has 2.5-GBase-T on motherboard, but I do have an Intel X520-2 for talking to SDRs, which I'm currently not using.
From knowing people who used that specific card in battery-powered devices, I do get the feeling that card specifically isn't the most energy-efficient end-to-end, but I haven't done a loopback test (X520 port A - SFP+ - 10-GBase-SR - SFP+ - port B, all artificially set to 1000Base speed) with a power meter for the whole system.
Show threadManawyrm | Sarah1d ago

@funkylab @nblr @ann3nova If energy saving is the target, there are some fancy very new chips on the market now from Realtek, etc., which are much much more energy efficient.

I still like to have my good Mellanox/Nvidia cards so I get their awesome driver quality (instead of the crap Intel/Broadcom/Chelsio/etc. are shipping).

Show threadMarcus Müller1d ago
@manawyrm @nblr @ann3nova uff, my only mellanox NIC is an ancient FX2, and that takes ~ forever to boot, and gets very very warm.
Show threadMarcus Müller1d ago
@manawyrm @nblr @ann3nova (but note that I bought that second hand like a good decade ago, I think? It might neither be the best model nor the best speciment)
Show thread~n1d ago
@manawyrm @ann3nova Was about to say… if you use bidi, you can get some really cheap and armored yet reasonably flexible fibers from china that are superduper thin with a connector that fits through fairly small holes. Just ordered some for a project and they were en-par with prices for decent cat7 copper cable.