First time fiber networking question

[CntrlAltDel]

Hi there, I'm planning to pick up a MikroTik CRS305-1G-4S+IN switch with FS SFP-10GSR-85 transceivers. This will be my first time delving into fiber and even though I read all the documentation and watched the videos I just want to confirm before pressing the button.

I'm stuck figuring out which fiber optic cable to use with this module, in the spec sheet it lists "LC" as supported connector. But when searching for these LC-LC fiber optic cables I'm seeing LC-APC, LC-UPC, LC-LC UPC and a whole lot of other connector type standards.

Could anyone confirm for me which fiber optic cable would be usable in this regard?

Also both ends will be using the SFP-10GSR-85 transceivers just fyi. My guess is that I'd need LC-LC but hopefully you guys can confirm.

FS.com SFP-10GSR-85

 

[CntrlAltDel]

Okay did some digging looks like I'll need duplex LC-UPC to LC-UPC connectors.

 

[drinkingbird]

Okay did some digging looks like I'll need duplex LC-UPC to LC-UPC connectors.

For standard ethernet at shorter distances, as long as it is LC you'll be fine. APC is superior as it has slightly less return loss, but only when you're up in the really high wavelengths or really long distances, etc. Obviously make sure whatever you need to plug into the other end is also LC but if it uses SFP it is, all common fiber SFPs use LC.

Just look for an LC to LC (or LC to whatever, but I'm assuming whatever you're plugging into is also LC) and you're fine. Most likely it will be UPC.

Far more important is to make sure you get a multimode fiber patch, since that SFP is Standard Reach (SR) which is Multimode Fiber with a reach of up to 300M on OM3 and 400M on OM4. Singlemode may get a link light but won't work correctly, if at all. Since I'm assuming you won't be going anywhere near those distances, either OM3 or OM4 patch will be fine, it just refers to the clarity of the glass. OM2 is pretty old but even that would work fine at shorter distances (not very common anymore).

The only other consideration is whether it is straight or cross. Most fiber patches are cross, however even if not, the vast majority of LC connectors now let you swap the TX and RX polarity (many of the old ones were molded into a single connector and you couldn't without breaking or cutting it). I haven't seen one of those old ones in a long time so I doubt you'd have to worry about it.

But if you connect two things together and get no link, swap the pairs on one end (either end).

 

[CntrlAltDel]

For standard ethernet at shorter distances, as long as it is LC you'll be fine. APC is superior as it has slightly less return loss, but only when you're up in the really high wavelengths or really long distances, etc. Obviously make sure whatever you need to plug into the other end is also LC but if it uses SFP it is, all common fiber SFPs use LC.

Just look for an LC to LC (or LC to whatever, but I'm assuming whatever you're plugging into is also LC) and you're fine. Most likely it will be UPC.

Far more important is to make sure you get a multimode fiber patch, since that SFP is Standard Reach (SR) which is Multimode Fiber with a reach of up to 300M on OM3 and 400M on OM4. Singlemode may get a link light but won't work correctly, if at all. Since I'm assuming you won't be going anywhere near those distances, either OM3 or OM4 patch will be fine, it just refers to the clarity of the glass. OM2 is pretty old but even that would probably work (not very common anymore).

The only other consideration is whether it is straight or cross. Most fiber patches are cross, however even if not, the vast majority of LC connectors now let you swap the TX and RX polarity (many of the old ones were molded into a single connector and you couldn't without breaking or cutting it). I haven't seen one of those old ones in a long time so I doubt you'd have to worry about it.

But if you connect two things together and get no link, swap the pairs on one end (either end).

Thank you this is really useful information. Now I can make a decision instead of just looking for words that match in the spec vs the product page.

I found this:
https://www.amazon.com/dp/B08BZB6YX5/?tag=snbforums-20

 

[coxhaus]

It seems like a lot of trouble for short distances in homes. They do generate more heat.

And don't look at it as it can damage your eye. Use a mirror.

 

[follower]

Hi there, I'm planning to pick up a MikroTik CRS305-1G-4S+IN switch with FS SFP-10GSR-85 transceivers. This will be my first time delving into fiber and even though I read all the documentation and watched the videos I just want to confirm before pressing the button.

I'm stuck figuring out which fiber optic cable to use with this module, in the spec sheet it lists "LC" as supported connector. But when searching for these LC-LC fiber optic cables I'm seeing LC-APC, LC-UPC, LC-LC UPC and a whole lot of other connector type standards.

Could anyone confirm for me which fiber optic cable would be usable in this regard?

Also both ends will be using the SFP-10GSR-85 transceivers just fyi. My guess is that I'd need LC-LC but hopefully you guys can confirm.

FS.com SFP-10GSR-85

I have CRS305-1G-4S+IN.
You just need

1. LC to LC om3 Multi mode duplex cable.
https://www.amazon.com/dp/B019OLTQIM/?tag=snbforums-20

2. SFP+ Module.
https://www.amazon.com/dp/B00U8Q7946/?tag=snbforums-20

Forget about other things.

 

[follower]

It seems like a lot of trouble for short distances in homes. They do generate more heat.

And don't look at it as it can damage your eye. Use a mirror.

Not just more heat but so hot. That's why I don't use it anymore.

 

[drinkingbird]

And don't look at it as it can damage your eye. Use a mirror.

Yeah mirrors make lasers totally safe. Why would you stare into the end of a fiber or SFP anyway (especially >100M where it is infrared and invisible)? In reality the only ones you really need to be careful around are really long haul like ZX and those do not ramp up to full power until they detect that both ends are connected.

But seriously, a mirror?

 

[drinkingbird]

Not just more heat but so hot. That's why I don't use it anymore.

Maybe that model router does, a multimode fiber SX SFP doesn't make any excessive heat, no more than a 10GbaseT would.

 

[follower]

Maybe that model router does, a multimode fiber SX SFP doesn't make any excessive heat, no more than a 10GbaseT would.

The heat is for this device itself. Sooooooooooo hot.

 

[CntrlAltDel]

Maybe that model router does, a multimode fiber SX SFP doesn't make any excessive heat, no more than a 10GbaseT would.

The transceiver and fiber cable recommended by @follower seems to be spec'd similar to the ones I have mentioned. Also the transceiver I have mentioned someone from reddit said that's the one they use. I still intend to stick with what I've listed, it wouldn't be an issue right?

 

[CntrlAltDel]

The heat is for this device itself. Sooooooooooo hot.

This I can deal with. I do intend to use the WHOLE 10Gbps throughput. Could potentially dremel a circular hole and add a 12v DC fan. It would be easy since I have a 12v DC PSU right next to it.

 

[drinkingbird]

The transceiver and fiber cable recommended by @follower seems to be spec'd similar to the ones I have mentioned. Also the transceiver I have mentioned someone from reddit said that's the one they use. I still intend to stick with what I've listed, it wouldn't be an issue right?

Honestly any SFP will work, maybe avoid the "caps lock and bash keyboard randomly" chinese brands but as long as it is a recognized brand from reputable seller, they're all basically the same, many manufactured by the same company (or at the very least using the same brand components).

 

[drinkingbird]

This I can deal with. I do intend to use the WHOLE 10Gbps throughput. Could potentially dremel a circular hole and add a 12v DC fan. It would be easy since I have a 12v DC PSU right next to it.

My guess is if the case gets hot, the case is probably acting as a heatsink with chips touching it, or internal copper/aluminum heatsink touching the case. I doubt they'd design it to fail so it is probably fine as is. Worst case airflow across the case is probably plenty. Adding a fan could actually make things worse, potentially severing that heatsink connection and/or introducing EMI etc.

 

[coxhaus]

Yeah mirrors make lasers totally safe. Why would you stare into the end of a fiber or SFP anyway (especially >100M where it is infrared and invisible)? In reality the only ones you really need to be careful around are really long haul like ZX and those do not ramp up to full power until they detect that both ends are connected.

But seriously, a mirror?

I grew up with fiber optics and the early ones were visible. People would look down them to see which was the receiver end and which was the transmit end.

 

[drinkingbird]

I grew up with fiber optics and the early ones were visible. People would look down them to see which was the receiver end and which was the transmit end.

Yes, 100 meg and below via MMF (short haul) was visible red light. And you'd have to stare at it for a long time to do damage (obviously still not recommended to do, but you don't need to look at it straight on to see if it has light or not, and straight on is the only way it will hurt you). Using a mirror would simply reflect the exact same light with the exact same damage (maybe slight attenuation) right into your eye.

Long haul, gig, 10G, etc are all infrared and not visible. Very unlikely that anyone is going to be using a 100M SFP (or any SFP with visible light) these days. If you want to see if it has light you use your phone camera (usually works, depends on the camera chip in your phone and the wavelength of the light) or an infrared detector strip. In reality, you just try it, if no link, swap the pairs. Faster than cracking out your phone.

 

[sfx2000]

And don't look at it as it can damage your eye. Use a mirror.

Please - do not use a mirror to confirm if a connection is hot... it's a really bad idea when dealing with lasers in general...

Depending on the PHY rate, you won't see anything anyways, as most these days are infrared - so it really comes down to two methods - one is simple, hotplug and it either works or not, or test equipment like a Fluke meter for fiber..

 

[drinkingbird]

Please - do not use a mirror to confirm if a connection is hot... it's a really bad idea when dealing with lasers in general...

Depending on the PHY rate, you won't see anything anyways, as most these days are infrared - so it really comes down to two methods - one is simple, hotplug and it either works or not, or test equipment like a Fluke meter for fiber..

Several other tricks available, even used by pros when they don't feel like pulling out the fluke. I've still got my little IR test card from 20+ years ago. Nowadays most use the phone camera trick.

One caveat, if you use the phone trick especially with ZX and even LX optics, don't point it directly into the camera, just look from an angle. Theoretically could damage the camera sensor in the phone.

The keychain sensor (just a strip of IR reactive material) was always very handy. They still exist, not as common.

 

[drinkingbird]