@domi The other side of these 25G links are 100G (via breakout), the cheapest way to do this is to get a 100G-SR4 optic, with a MTP/MPO break out cable.

The comes out to (per 4 25G ports) for multimode:

$39.90 | 100G-SR4 Optic
$31.62 | MPO Breakout to 4x LC
$67.60 | 4x25G SFP28's

= $111.42 for 4 25G ports

For singlemode this would be:

$153.90 | 100G-PSM4
$107.60 | 4x25G SFP28's
$38.91 | Breakout cable

= $300.41 for 4x25G's that work the same, just SM

I don't really see a good reason to do SM if it's not going via any patch panels

re: noob question

@wolf480pl @domi Yes, they are running on very different wavelengths of light, 850nm (Basically IR) for MM, and 1310nm for SM

You can (and I often do in a rush) use the "wrong" cable for short distances though, but obviously no one is going to help you if it goes wrong :P

re: noob question

@wolf480pl @domi Haha, _well_

10GBASE-SR/25G-SR/1G-SX is suppose to only be ran on MM fiber, In general it wont hurt (other than optical power I think) to run it in SM, but MM fiber is cheaper so "why" (other than it's what if you have)

1G-LX/10G-LR/25G-LR is suppose to only be run on SM fiber, but will sorta run on short 5m or less runs of MM fiber without too many problems

The main reason people hate MM is because the glass core is a lot thicker, it typically has a lot more problems with signal integrity, and so if you add patch panels etc, or just go longer haul, stuff gets more risky/troublesome a lot quicker, given peoples time is valuable, and DCs are non friendly spaces, people tend to prefer doing everything in DACs or SM cable+optics

@domi ye, the problem is that sometimes advice propagates until it has it's context removed and becomes a meme, and so people just end up drumming on about something without the context to why things like MM are bad (in some cases)

@nblr TIL this exists, and it looks quite funny

@wrmsr yeah I might buy another MPO cable to play with, I didn't have any spares so the current state had to do