Recovered Expert2d ago
Manawyrm | Sarah

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 :)

Mar 24 at 10:27amWeb
Show threadanne.💫4d ago
@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? :)
Show threadManawyrm | Sarah4d 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.💫4d ago
@manawyrm Heck yeah. I'm already making a list...thank you. :)
Show threadMarcus Müller4d 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 threadhcsch4d 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 | Sarah4d 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 threadhcsch4d 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 Müller4d 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 | Sarah4d 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 Müller4d ago
@manawyrm @ann3nova nice, that's super helpful!
Show threadManawyrm | Sarah4d ago
@funkylab @ann3nova Seeing (and thinking about) this number made me realize why I like my solar setup soo much... 😆
Show threadMarcus Müller4d 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~n3d 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 Müller3d 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 | Sarah3d 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 Müller3d 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 Müller3d 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~n3d 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.
Show threadAliveDevil4d ago

@manawyrm
Yeah, basement renovation will feature some lengths of fiber in cable channels, because I hate the way cables have been installed here.

Networking cable, power cable, etc. all through the basement ceiling/entrance area floor, at an angle at a wall, with a thumb worth of clearance.
I've had issues getting CAT5 through there, but two strand fiber was a breeze.

Show threadAliveDevil4d ago
@manawyrm
People installing the power cables were like "Where should the cables land?" and whoever was in charge said "this wall/corner - just drill a hole down".
Show threadMarcus Müller4d ago
@manawyrm how do you do the mechanical part of pulling the cable through walls? I have a flat with power outlets that I hope are connected via contiguous pipes, but there's obviously already a power cable in these. Can that still work?
Show threadManawyrm | Sarah4d ago

@funkylab In this case, I didn't have to, because there cable channels along the way (just some walls to drill through).

There is "fish tape" (often called "Einziehhilfe") here, which you can force through the cable channels somehow (if it's actually a pipe, you can hook a bag up to one end and use a vacuum cleaner to suck on the other end of the pipe!).

Then just duct-tape the fiber to the fish tape and pull it through.

Show threadAliveDevil4d ago
@manawyrm @funkylab
Speaking of which, are there prefabricated cable channels with embedded fish tape?
Show threadJoe4d ago
@manawyrm
I was just about to install more copper into my apartment and workshop. Thank you for the heads up.
Show threadtnt4d ago
@manawyrm Definitely. And Ill also add, if you have to, the mechanical splices are cheap and not that hard and if you have only one in the link, not a problem ... and then the holes you need are literally 2 mm ...
Show threadpenguin424d ago
@manawyrm Did you use a pre-terminated cable?
Show threadManawyrm | Sarah4d ago
@penguin42 Yes, 50 meters dual fiber OS2, steel-reinforced cost me only about 30$
Show threadjzdm3d ago
@manawyrm could you provide a(shopping) link to the fiber, please? Thanks!
Show threadCyberstern3d ago
@manawyrm absolutely agree. Even unarmoured cable is easy to work with for most things (and it’s small enough to be embedded into caulking, so you can easily run it inside wall corners and just hide it without any issues) if only switches with multiple sfp+ ports would be a bit cheaper… you mostly can get some with 1 or 2 ports, if you need more it gets expensive fast…