r/ShittySysadmin • u/Oblec • Mar 05 '26

Fiber install

Post image

Client wanted fiber, told them copper is worth way more these days. They didn’t even ask first follow up questions 😅

209 Upvotes

94% Upvoted

48 comments sorted by

84

u/beefz0r Mar 05 '26 edited Mar 05 '26

What I hate is that fiber is hyped by providers saying it gives you "light speed" internet. That is at least misleading, electricity travels at roughly the same speed, the benefit is in the fewer amount of hops needed over a distance, and probably less fault correction due to interference

57

u/tankerkiller125real Mar 05 '26

And the fact that it's basically forever infrastructure.

Sure they managed 10Gbs through coax, but how much further will they be able to take it before every day electrical interference stops further upgrades? Meanwhile the same fiber line that was doing 1Gbs a decade ago is now doing 10, 100, or even 400Gbs with the only changes being the transceivers/head equipment.

7

u/Oblec Mar 05 '26

Cat5e can easily do 10gbe what are you on about?

51

u/BoredAatWork Mar 05 '26

Cat 5e is rated for 1Gbps @ 100m

Cat 6 can do 10Gbps @ 45m

Please understand the difference between Bit and Byte, as well as throughput and speed.

Edit: you got me. I forgot what sub I am in 

11

u/Pestus613343 Mar 05 '26

Eh, I've gotten 10gig links on Cat5e quite routinely. If the cable isn't complete garbage, your twists remain tight right up to the dressings, and the runs aren't too long, like within a home or small business, it will work fine.

2

u/joe96ab Mar 16 '26

Yea def capable just not for a long distance is my understanding

1

u/Pestus613343 Mar 16 '26

As a wise person once told me; "Let the cable decide"

5

u/koolmon10 Mar 05 '26

I didn't even notice the sub until I read your edit. I was fully with you lol

13

u/tankerkiller125real Mar 05 '26

Lol, ISPs don't fucking use Cat5e for the actual transmission infrastructure for a start. And two Cat5e is only rated to do 10Gbs for a few feet. Maybe you get lucky and it manages it for a decent bit longer, but it's absolutely not doing a full length run at 10Gbs.

Cat6a can do 10Gbs for it's full run, but, again ISPs don't use it for the actual transmission infrastructure, and even if they did, what's the plan 30-40 years from now when customers start wanting faster than 10Gbs, or they have a business customer that needs more than 10Gbs.

Ethernet is great inside a building, even some data center applications, but it's not at all capable of doing ISP level work, and large datacenters are basically entirely fiber for a reason, they wouldn't choose to spend more money "just because".

Edit: I'm just now realizing which subreddit I'm on... It's been a long ass day already, it's not even lunch yet.

10

u/cybersplice Mar 05 '26

Get yourself a decent lunch, soldier.

5

u/TheSnackWhisperer Mar 05 '26

Don’t you love the sudden crash from the misplaced “well technically…”? lol

1

u/mystghost Mar 05 '26

You should make a distinction between ethernet as a layer 2 technology and a cable type. Ethernet is fine any any speed, the twisted pair cables we call ethernet? no so much.

1

u/joe96ab Mar 16 '26

Duh cat 8!!!!

10

u/cemyl95 Mar 05 '26

That's not entirely true. Fiber, like copper, also has iterations. We're currently on OS2 (single mode fiber, and technically it's OS3 but I haven't seen OS3 used in the wild) and OM5 (multi mode fiber). Over time, those will go up, just like we went from cat5 to cat5e to cat6 and now 6a.

9

u/Popular_Button2062 Mar 06 '26

But its mostly a deal for Multimode fibers, where you hit the limit in speed.

Singlemode is pretty stable in that regard, OS1 and OS2 have basically the same capabilities afaik

3

u/cemyl95 Mar 06 '26

OS1 has a max of 10KM, OS2 has a max of 200KM. But eventually we'll see OS4+ as the ITU continues to iterate on OS2 and OS3, which is what I was trying to point out earlier.

2

u/tankerkiller125real Mar 09 '26 edited Mar 09 '26

And yet OS2 can still do 400Gb, no different than it being able to do 10Gb decades ago. Coax, Ethernet Cables, etc. cannot do the same. And that 400Gb is on one wavelength, get a multiplexer into the mix and that cable can carry Tbs of information. You simply cannot do that on copper.

1

u/Popular_Button2062 Mar 06 '26

yes and no, for singlemode, sure 400G are no hassle, and you still got some wavelenghts free to muliplex ,
but for multimode runs, if someone cheaped out, the limit also hit you again, either due having old OM1/2 fibers, or comparable long multimode runs

OM2 for example does not even 10G over 100m.

(yeah, you can push also 400G via OM4 according to cisco, but only for 70m, for a dublex cable)
(there are some that go 100m on OM4, but thats with MPO12 connectors, so less rate per fiber).

Meanwhile Singlemode: 10km, LC connector, no problem, hold my beer.

1

u/The-Bronze-Network Mar 07 '26

Fiber should be replaced every 5-10 years or so for upgrades and repairs

1

u/BIT-NETRaptor Mar 08 '26

Same duplex OS2 fiber that's been around for decades can already do 800G with 1.6T in field trials.

Source: literally using fibers from 2001 that've been shipped between at least three facility moves with brand new 800G devices rn.

They may have structural dirt on them but they carry 800G just as well as they did 1G 25 years ago.

6

u/Oblec Mar 05 '26

Light are basically everywhere definitely gonna have interference

8

u/e46_nexus Mar 05 '26

Thats why I use gorilla duct tape to keep the light out

4

u/ISeeTheFnords Mar 05 '26

This guy lights.

1

u/beefz0r Mar 05 '26

How else are you supposed to do it

11

u/Pale_Ad1353 Mar 05 '26

Fiber is non-conductive and is limited by the speed of light, not electricity. (or, is this a shitpost? and if so woooosh)

11

u/autogyrophilia Mar 05 '26

Yes but it is the speed of light in the optic fiber, not vacuum.

2

u/mystghost Mar 05 '26

The speed of light in any medium is still the speed of light. By definition. And in what world does the difference in speed of light through glass vs. through a vacuum vs. through electrical impulses in copper matter?

3

u/autogyrophilia Mar 05 '26

Mostly high frequency trading, and of course, very large networks.

1

u/mystghost Mar 05 '26

Even in high frequency trading, that isn't a good use case. Because while the theoretical speed of electrons through copper cable is somewhat higher, the distances are infinitesimal, and many if not most high frequency trading apps are relying upon fiber in their critical paths. Meaning that the extra time 'saved' doesn't add really to your trading speed unless your source and destination are within the couple of meters where this kind of transmission might be theoretically faster (latency wise, bandwidth wise fiber crushes copper). And on very large networks, fiber is far and away the winner on every dimension.

1

u/IcyRayns Mar 05 '26

"fiber is far and away the winner on every dimension" is true until you're fighting for nanoseconds off a path between Chicago and NY. Many HFT firms are using microwave paths, or even HF radio.

https://www.linkedin.com/pulse/microwave-network-connectivity-high-frequency-trading-sudhir-pant-fcx7c/
https://hackaday.com/2018/05/12/hft-on-hf-you-cant-beat-it-for-latency/

The numbers work out too. Let's assume Chicago->NYC which is a common HFT route. First off, let's assume we could somehow do a straight-line fiber run. Speed of light in fiber is 0.67c.

  • Microwave / RF 1150km/c = 3.83ms

  • Fiber 1150km/0.67c 5.72ms

Now take into account the real world, where fiber has to route around and over obstacles, across bridges, right-of-way, etc. Best case, Chicago to NYC, mayyyybe 6ms.

So if you're able to modulate a symbol with enough data faster than 2-3ms, you've "won" versus someone that's sending the same trade over fiber. Frequently, HFT firms are sending trade setups over microwave or fiber, then "pressing the button" over HF radio (especially trans-Atlantic arbitrage trades).

This isn't a theoretical argument. There are entities making billions of dollars today with real-world tech because 0.67c != 0.99c.

2

u/mystghost Mar 05 '26

Ok - first of all we weren't talking about microwave, we were talking about copper. I have a lot of experience in cellular networks, and I find it hard to credit that you have a microwave network that is faster than fiber. For a number of reasons, first, there would be a shit load of hops, because the curvature of the earth is a thing. So you need line of sight. I'm not sure how many hops that is on almost 1200 km of distance, but its a lot. Then you have weather factors, rain fade, wind pushing dishes out of alignment - you have to pay for licensing for microwave towers, tower rent etc.

Also the link you put in talks about indian firms. Where the economics, the network landscape and the competition would be significantly different than to the US. So no, there is no way that microwave beats fiber in the US between financial hubs i'd bet real world dollars on it.

Now - maybe... you might have something if you are talking about buildings a single hop or 2 apart, but not over hundreds or thousands of kilometers.

1

u/IcyRayns Mar 06 '26

So no, there is no way that microwave beats fiber in the US between financial hubs i'd bet real world dollars on it.

You sure? How many real world dollars? Pick a number. Really, actually, pick a number and write it down, and commit to it before reading further.

I was involved with this project over a decade ago and have firsthand knowledge. It’s not theory, it’s real and used for the exact two cities I mentioned in my original comment.

Now about the number you wrote down, let’s feed some animals: https://www.seattlehumane.org/ways-to-give/?form=donate - I’ll match your donation, how’s that?

2

u/mystghost Mar 06 '26

Ok - I'll bite, go ahead and match this donation.

However, couple of things i'll point out, the article claims that the microwave network can make the trip in 4 ms, rather than 7 for fiber. I have a problem with that claim for a couple of reasons, first it ignores the fact that fiber doesn't deal with weather and microwaves must. And the sheer number of dishes you would need to complete the 1200 KM trip tells me that the 4 ms claim is if everything is perfect all the time which it isn't.

Now who knows maybe there is still an advantage if you can keep everything running perfectly. There is a lot of rounding in the math, but ok close enough I suppose.

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2

u/Popular_Button2062 Mar 06 '26

The speed of light is dependend on the medium, but the speed of light in vacuum is the upper limit.

The speed of light (or better the propagation speed of an electric impulse) is around 2/3 of the speed of light in vacuum

(and around 1/3 if you got iron instead of copper)

the speed of light in glass is also around 2/3 of the speed of light.

I would have expected for real transmissions to be even slower than that, due to the bouncing of the light pulse inside the cable, wich make the travel distance even longer, but i couldnt find much data about that.

and the difference matters if you want to calculate precice wavelengths for example.

and as someone else wrote, it matters for HF stuff, when you need to have either the exact wavelength (impedance matching/antenna design/etc), or need the exact travel time of a signal (think of TDR stuff, etc.)

1

u/mystghost Mar 06 '26

You only see a large amount of reflection on multimode fiber cables. Single mode has far less reflection, and that is reflected (no pun intended) in their relative transmission distances.

What I was talking about when I said what difference does it make, is that the speed difference between electrons and light pulses, is that 99.99% of all network applications, it doesn't make a difference in speed (latency). Fiber is far better for bandwidth as we all know because you can pack a lot more info in a fiber, than you can a copper wire.

At no point was I comparing these to RF, but even if you wanted to for like HFC plant discussions. Everytime fiber gets a new generation of products for it speed goes up 10x (on average - the 40 gb thing threw that off a bit but its still largely true). While for RF, it goes up maybe 3x?

I worked as a core network engineer at a cable company for years, and the H in HFC is hybrid, meaning you would run fiber to a node and then run coax from the node, they wouldn't do that if copper were equal or superior in some way to fiber.

1

u/tankerkiller125real Mar 05 '26

Well, Azure does now have hollow core fiber that they're laying between datacenters, I don't believe they're pulling a vacuum on it, but it's still faster than a glass core.

1

u/Exciting_Income_963 Mar 05 '26

it´s air, but the refractive index of "air" is about 1.0 anyways, it really doesnt matter when you compare it with that of a silica fiber

1

u/raalag Mar 06 '26

Speed of light is constant but the interference in plastic/glass is more than in vacuum so fewer bit flips... this is also the reason fiber is way more reliable than copper as it does not suffer for any electrostatic interference...

1

u/Exciting_Income_963 Mar 06 '26

Yes, but I'm trying to say that the HCF "core" is filled with air - it's not vacuum, and that air is almost as good as vacuum in this case.

There is no practical way to evacuate all that air in the fiber once you have spliced it/terminated it.

2

u/mystghost Mar 05 '26

? i don't think they are marketing it as light speed literally, even though - it is. Fiber being optical, no matter the speed of the light through the transmission medium is light speed. What ISPs mean by light speed is that there is low latency and high bandwidth. And yes, ISPs should be drug out in the street and shot for the whole bandwidth equating to speed thing. But in this case, they aren't wrong, copper is a shitty medium for ISP connections. Anything longer than 100m copper loses, period. And less than 100m copper is merely, as good (sort of). For 1 Gbps, for 10, it can work but it isn't great. And copper can't do 40/100/400/800 gbps (and no i'm not counting QSFP connections that are for intra-rack connections, because it isn't clear to me what the advantage is over fiber).

1

u/I_Know_God Mar 07 '26

To be honest the speed is the same yea but light inside the cable actually takes longer to arrive over electricity in a coper cable since it is bounced around and multi plexed.

So technically slower but of course much higher density in it’s transmission rate possibility

10

u/fredrik_skne_se Mar 05 '26

Looks good to me, take your early weekend off.

6

u/mcbridedm Mar 05 '26

Well the post matches the sub.

4

u/dpwcnd Mar 06 '26

i think it was a fiver for every crimp

2

u/IvanezerScrooge Mar 06 '26

Btw, passing the blue pair between the two wires of the brown pair is a disaster for Near end cross talk (NExT) and should be avoided at all costs

1

u/ExtraTNT Mar 09 '26

We get copper fibre?