(US Ebay) SFP+ 850nm 10gb transceivers

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juw

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Jun 7, 2023
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Advertised for distances up to 300m, would these transceivers need optical attenuation for short distances?

Or do I interpret "300m" incorrectly as a measure of distance?

Thanks!
 
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juw

New Member
Jun 7, 2023
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no, you can du 0.2m without, heck, even on 10km you can do that
Sadly, I am lacking experience with this, as I mostly used DAC cables before.

I just read that the laser emitters in long range receivers are designed to take the optical loss over longer distances into account, thus being far brighter than the ones for shorter distances. Without this assumed optical loss using short optical cables, the receivers are said to be quickly defunct due to that overload.

Thank you very much for your reply!
 
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Prophes0r

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Sep 23, 2023
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no, you can du 0.2m without, heck, even on 10km you can do that
Attenuation is needed on most transceivers rated for more than 1km.
Some can handle the higher power on their receive end, but it is not standard.
That's why low power Single Mode receivers exist.
Datasheets are often less than helpful, since they almost always use the numbers from the standard itself.
And the standard receive power threshold for 2km transceivers and above will require attenuation.
This doesn't mean they won't work. It just means the transceiver is technically "better" than the spec they are quoting.

A better rule of thumb is that Multi Mode transceivers usually don't need attenuation since they are made for in-facility connections.

And since these are MM transceivers, they should be fine.
 

Prophes0r

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Sep 23, 2023
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Sadly, I am lacking experience with this, as I mostly used DAC cables before.
If you are starting fresh with fiber, you should really be looking for Single Mode gear.
There is little if any cost difference, and you won't need to replace it.

It will require that you do actually pay attention to the specs of the transceivers, since you don't want to be blasting away with a 50km one over 1m of fiber, but it is still trivially easy to find good/cheap ones.

There is basically no reason to use Multi Mode fiber unless it's already in your walls, or you have the equipment in your closet already.
 
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MountainBofh

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Mar 9, 2024
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I would say there is 2 small benefits to MMF vs SMF.

1. There's a bit more of a selection for MMF transceivers on the used market.
2. The MMF transceivers are a little bit cheaper.
 

Prophes0r

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Sep 23, 2023
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It depends on the day really.

The difference in cost/availability can also be meaningless for a HomeLab too.

These transceivers are less than 1$ each shipped with their ~$9 cost.
I bought 12x SM ones for $14 shipped a few months ago. Technically those were more than $1 each.
But is that really a meaningful cost difference when we are buying in low volumes?

When the fiber costs 2x-25x more than a used transceiver, I'd argue no.

Speaking of fiber costs, unless someone is liquidating, I've been finding SM fiber to be cheaper than MM fiber, so the total cost will likely be lower with SM in 2024.
 
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Markess

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May 19, 2018
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Late to the party, but thought I'd mention that I'm using around a dozen of these AOI transceivers in my homelab with no issues. I've used them for 5 & 10 meter runs and with a handful of ex-Lenovo CX-4 cards in the rack that didn't want to play nice with the DACs I had on hand. So I think short distances work fine for these.

As you'd expect, they do draw more power than a typical DAC. In my primitive tests with an 8 port passively cooled switch plugged into a Kill-a-Watt, the difference is just under 1 watt each for these over generic Cisco DACs over 3 meter length. Not a lot, but could be an issue depending on use case.

@Prophes0r is probably right that right that total cost of ownership for Single Mode would be less if starting from scratch. But, since my lab is all used, cast off, and hand-me-downs, Multi Mode wound up being cheaper for me.
 
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klui

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Feb 3, 2019
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Commscope makes a couple of items that will help. I recall @Stephan is in EU but they should have something similar that is compatible with the common faceplates where he's at.

They make an M13FP-TR (760091231) 760091231 | M13FP-TR-262 (WHITE) HIGH PROFILE. It's a tamper resistant faceplate with a clear protective cover where it is secured with a torx screw. You can swap the torx with security screw. https://www.commscope.com/globalassets/digizuite/53005-860-383-090-issue-2-8-27-2013.pdf

Another is their M14MMO (107655185) 107655185 | M14MMO-262. While it's not as tamper resistant as the M13FP, it has a hood that slides down the faceplate from the top. It also includes a small fiber spool. https://www.commscope.com/globalassets/digizuite/52862-847-704-129-issue-3-8-27-2013.pdf

The disadvantage of these faceplates is you can't use industry standard keystones. You need to use Commscope's proprietary M-series jacks: MGS400 (Cat6), or MGS600 (Cat6a). The M13FP-TR needs an additional adapter (M30FP-2RJ45) so their jacks will attach. Of course they have their own filler blanks. It is compatible with copper jacks; and LC, SC, and MPO couplers through UNFA-EMM-SC01 adapters. The M14MMO will also allow you to mount 2 duplex and 2 regular jacks in a 2x2 configuration. 6 total jacks. There are tandem LC and MPO couplers that will install.

The only benefit of using these parts is they have an additional layer of protection.
 
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Prophes0r

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With kids around, who might unplug things and look into a 1320nm beam, multi-mode seems safer.
Why.... would there be any difference?
On a low power <1km optic, the danger would be about the same.
850nm MM transceivers are NOT safe to unplug and look into anyway.

That's like saying you prefer to drive a Diesel vehicle instead of a Gasoline one, because your kids like to play with matches next to fuel spills.
I mean...sure? Gasoline flashes far more easily...but neither is remotely "safe".

Note: LC connectors are pretty stiff and spring loaded. They absolutely should not be easy to disengage. They certainly aren't child safe, but a kid isn't going to accidently or casually uncouple one. They would really have to squeeze down on it. By the time your kid has the manual dexterity and hand strength to open one, they are probably old enough to understand that unplugging one and looking into it is dangerous.

So I suppose there must be some combination of a 2-year old with gorilla hands that can open child safe bottles, but you still need to lock your kitchen cabinets because they can't be trusted not to drink the bleach you store there?

I'm not going to tell you now to protect your kids, but if you are genuinely worried about this, you probably have a LONG checklist of other child safety things to do first before this is even remotely the worst threat.
 
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Prophes0r

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Sep 23, 2023
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FYI: I'm going to put fiber below "beginner power tools" in terms of danger during an install.

Like, a hand drill. Don't pull the trigger while also holding onto the spinny-cutty-drilly part.

If you are being careful enough not to get the fiber dirty, you are easily aware enough not to stare into the laser.

This isn't firearms safety, mains power, or unsupervised table-saw use or anything.

After installed?
I dunno...like leaving a piece of strong string laying around? I guess they could choke themselves with it?
Letting them use metal utensils?
Having a box fan on?
 
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