Author Topic: LC/LC cable termination - worth it?  (Read 3901 times)

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Offline cncjerry

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LC/LC cable termination - worth it?
« on: October 09, 2021, 07:37:47 pm »
Summary. - what's the best way to easily terminate multimode fiber at home using some of the new quick connectors, I guess?

I'm putting in 10Gb ethernet for my lab machines and private cloud server.  I was going to go with 2.5Gb but 10Gb was less expensive.  The cards with SFPs can be had for $39 per end and the fiber is cheap.

I'm trying to figure out if it is worth it to buy a fiber termination kit, a cheap one for like $70, versus just buying more cables.  On day one, a deer chewed through an expensive 50m cable (from early IBM days) I had hanging out a window while testing.  Then I ran over a 10m cable with my chair, that one still works but I'll probably not use it.  I also had a rodent bite one, that still works.

I know the early connecters required epoxy, polishing, etc.  It looks like the new connectors, and that's the reason for my question is I don't know which ones, don't need all that epoxy and polishing, you just strip, cleave, insert and off you go.  But I can't find the LC connectors I see in the videos.  The ones I find are more expensive than the pre-made cables.  For instance, I can get 10m om3 multimode LC/LC duplex cables for less than $10 per.  30m aren't much more.  I'm using cisco SR SFP+ that cost less than $8 per.  The LC quick connectors seem pretty pricey, even the cheap one is a couple bucks, then you need the cable, which in my case I might have, but the kit is $70.  Also dangerous as I had a piece hit my face under my eye and goggles and I have a very small piece of glass in my hand from the one the deer chewed.  So adding it all up, I can buy a half dozen spare cables but if the rodents get to it under the house continuously, then I'd rather make my own, maybe. 

I looked at using cat7 and lesser cables and the copper SFPs are like $45 per end so the fiber is definitely much less from an initial investment.  The Mikrotik switch I bought is unbelievably functional for less than $140 shipped, it has routing and switching OS built in. 

what are others doing?

Jerry
 

Offline mansaxel

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Re: LC/LC cable termination - worth it?
« Reply #1 on: November 19, 2021, 09:27:50 am »
Summary. - what's the best way to easily terminate multimode fiber at home using some of the new quick connectors, I guess?

<snip>

what are others doing?

Jerry

The rest of us try saving people from having to use multimode. Singlemode -- especially so when running 10G and up, is simply better. And at the same price, why not just switch?

Problems with single mode are of course termination unless you can satisfy with patch cords only. I usually go around that by pulling premade patch cords in conduit or when I really need it, pay someone to do fusion splicing for me. I keep an eye out for a cheap fusion splicer, but no luck yet.

In your situation, I'd just buy patch cords and be done with it. The cheap China stuff from fs.com or similar is quite up to spec. Don't bother with termination kits unless you're installing and need fusion splices to pigtails. 

But inspect and if necessary clean your connectors. Clean connectors are orders of magnitude more important than anything else in creating a reliable optical system. Put your money in a microscope for that, and in cleaning supplies.
« Last Edit: November 19, 2021, 09:32:25 am by mansaxel »
 
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Offline madires

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Re: LC/LC cable termination - worth it?
« Reply #2 on: December 05, 2021, 11:32:11 am »
To protect the fibers from rodents place them in conduits or get outdoor fiber with rodent prodection. Be a bit careful with short runs of singlemode fiber. Check the link budget and make sure you don't overdrive the SFP's receiver. Add an attenuator if needed.
 

Offline mansaxel

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Re: LC/LC cable termination - worth it?
« Reply #3 on: December 05, 2021, 01:24:43 pm »
To protect the fibers from rodents place them in conduits or get outdoor fiber with rodent prodection. Be a bit careful with short runs of singlemode fiber. Check the link budget and make sure you don't overdrive the SFP's receiver. Add an attenuator if needed.


I do remember the issues with SDH line cards back 20 years ago, when one had to carefully check the receiver stats and put attenuators in place, but there's been some development since then.


Modern Ethernet (gig, 10gig) transceivers aren't very sensitive to overload; most of the time their dynamic range is quite up to it. There's no problem in running a "10km" transceiver via 2m patch cord only.

This is a "10km" 10G transceiver via 2m patch cord, 25 m trunk fibre, and again 20m patch cord. All ferrules inspected and cleaned prior to connecting:

Code: [Select]
carport# sh inte te 1/29 transceiver
ITU Channel not available (Wavelength not available),
Transceiver is internally calibrated.
If device is externally calibrated, only calibrated values are printed.
++ : high alarm, +  : high warning, -  : low warning, -- : low alarm.
NA or N/A: not applicable, Tx: transmit, Rx: receive.
mA: milliamperes, dBm: decibels (milliwatts).

                                 Optical   Optical
           Temperature  Voltage  Tx Power  Rx Power
Port       (Celsius)    (Volts)  (dBm)     (dBm)
---------  -----------  -------  --------  --------
Te1/29       31.1       3.26      -2.5      -3.4   

carport#sh inve "TenGigabitEthernet1/29"
NAME: "TenGigabitEthernet1/29", DESCR: "SFP-10Gbase-LR"
PID: SFP-10G-LR        , VID: V02  , SN: OD2004160027

The Alarm threshold of this transceiver is +3.4dBm, and I approximate the loss as 1.3dB based on the stated -2.1dBm TX level from the other end. Even if the loss was a mere 0.2dB, equal to 2 patchings and 0dB loss from cable (A near-perfect patch point loses about 0.1 dB) there would be more than 2 dB headroom up to the Warn threshold of +0.4dBm.


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