Which fiber should I install in a new building?

rootpeer

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Oct 19, 2019
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I'm going to install some fibers at work too for AV-networking so I'd like to inquire this information more deeply: Wikipedia tells me that 100Gbit/s is possible with OM3/4 up to 70/100m. OM5 already exists too and supports even 400Gbit/s. My longest run will not exceed 50m. So I'm planning to install OM4 or OM5 since we will need just 10Gbit/s now and maybe 40Gbit/s in a few years.
Is there anything I'm missing? Is there any good reason to use Singlemode instead?
For 40Gb on single mode (OS1 or OS2) you need just 1 pair of fibers.
For 40Gb on multi mode (OM3) you need 4 pairs of fibers.

For 100Gb on single mode (OS1 or OS2) you need 1 pair.
For 100Gb on multi mode (OM3) you need 10 pairs.

This was the norm with 1 pair of multi mode fibers being able to do 10Gb max. So to get higher speeds, you use multiple pairs on the same transceiver (QSFP+, etc). The 40Gb+ single mode optics accept LC fibers while the multi mode need MPO cables that carry numerous fibers.

There might be transceivers with modulation technology out there that possibly use less multi mode fibers, I am not sure about that. The newer multi mode transceivers also support 25Gb/pair instead of 10Gb/pair.
But in general, multi mode fiber cables get bulky for 40Gb+ applications and the cables come with fixed number of pairs inside them, so to transition from 40Gb to 100Gb you either need another cable or have to adapt multiple cables to a single connector depends on how many pairs there are in the original cable.

With single mode, you use a duplex LC connector for nearly any speed. Plug and play.

In short, a single pair of duplex LC single mode fiber (2 fibers) can do up to 400Gb.
Whereas you need a 12-pair MPO multi mode cable (industry standard) to do 10-100Gb and a 16-pair MPO multi mode cable to do 400Gb.
With a single mode 12-pair MPO you can theoretically split it to up to 6x 400Gb links.
The difference is distance and density. Also MPO cables tend to be more expensive but so do single mode transceivers.

I have not used 40Gb+ multi mode so take the above with a grain of salt.
 
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Scarlet

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Today I received my test Setup to familiarize myself with the singlemode stuff - everything but the "short" 10 m trunk cable will be used in the house:

I have another MTP fanout cable with a male MTP-12 connector coming to test the other side of the keystone.

I learned something (could have guessed from the specification of Polarity B, but had to try this myself):
Connecting the port labelled 1/2 on one cassette is connected to the port labelled 11/12 on the other cassette.

This does not work:
does_not_work.jpg

This does work:
does_work.jpg

I put the MTP coupler in a keystone that originally had a LogiLink NK0030 Singlemode LC-Duplex coupler installed. The MTP coupler fits perfectly but requires 8 cm from the front of the keystone to where the fibre starts bending. So this could get a bit tight in the wall.
mtp_coupler_in_keystone.jpg
 

Scarlet

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For 40Gb on single mode (OS1 or OS2) you need just 1 pair of fibers.
For 40Gb on multi mode (OM3) you need 4 pairs of fibers.
From what I've read on singlemode fiber multiple frequencies are used in parallel.
On multimode fiber it is always the same frequency but used on multiple fibers in parallel.
 
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rootpeer

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From what I've read on singlemode fiber multiple frequencies are used in parallel.
On multimode fiber it is always the same frequency but used on multiple fibers in parallel.
That is what I meant with modulation technology.
I think it is not typically used for duplex fibers, I think the main application is FTTx or applications where you want to have 1 fiber instead of 2 (BiDi optics).

I think the speed difference is mainly due to modal dispersion on multi mode fiber, where a signal fired first might arrive after a signal that is fired later because it happened to bounce around inside the core more. That means there needs to be processing to figure out the correct order of the signals and that ultimately sets a limit on how fast the technology can be.

The single mode fiber is so tiny that light cannot bounce around and thus signals arrive on the other end in the correct order but that means that the tolerances of the optics are insane, hence the increase in cost.
 
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nasi

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Thank you for all your explanations and test-reporting. That helps me a lot.
I guess I'm going to buy some of that FS stuff too.
 

Scarlet

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I'm trying to wrap my head around TIA 568 Method B cabling and adapters. If I got this right then an odd number of Type B components will behave the same as one Polarity B Trunk Cable.

  • One Type B cable connects Fiber Position 1 to Position 12, 2 to 11 and so on
  • One Type B coupler (Key UP / Key UP) connects Fiber Position 1 of one cable to Fiber Position 12 of the other cable, 2 to 11 and so on
So if I use two Type B cables and one Type B coupler this should behave the same as if I used exactly one Type B cable, correct?

Mapping this to my Plan for the house:
How does a Type B breakout / fanout cable fit in here (e.g. this cable with a male MTP-12 connector: Customized 8-144Fiber SMF MTP-12 MTP® Breakout Cable )? Can I replace a Type B cable plus cassete with this or is there a chance to get this wrong? I'm thinking about skipping the cassette in the office by using the breakout cable.
 

Scarlet

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Bonus Question: Can anyone recommend a method to test the fiber once it's installed that is more profound thant just "plug in a switch at both ends and see at what speeds the link comes up"?
 

LodeRunner

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That is what I meant with modulation technology.
I think it is not typically used for duplex fibers, I think the main application is FTTx or applications where you want to have 1 fiber instead of 2 (BiDi optics).
There are 40 Gb BiDi optics that'll run on a single OM3/OM4 MM pair. Great for 10 to 40 upgrades.
 

Scarlet

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Bad news, the contractor managed to destroy the fiber while pulling it through conduit :(

Now I need a replacement for a 25m 12-Fiber OS2 9/125 MTP® Trunk Cable, OFNP (Female - Female). Polarity can be A or B, I can just switch the cassette on one end if needed.

Can anyone recommend a product that I could search for on *bay or a supplier that does not take 2 weeks to deliver for such a cable to Germany?
 

klui

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Single mode fiber always have angled polished ends. Verify your cables' specification(s): MM will mostly state PC/UPC (flat) while SM will state APC (angled). For MPO cables it means angled ferrules will butt against each other in an unsupported manner if you have their high ends meet. The standard is to have high side match with the key. You don't want to insert APC MPO connectors into a key up to key up adapter or you will damage the ferrules. See
and​

from The FOA Reference For Fiber Optics - Testing Cables with Multifiber/Array Connectors.

In order to change polarity on SM MPO cables you must use the correct cable ends (method and gender) and not a coupler/adapter. As you've discovered, daisy chaining an odd-number of method Bs will provide the correct polarity for parallel connections. If I could afford to buy the correct custom cable from FS, I would just use method B for a patch-trunk-patch topology. My trunks would be pinned and all patch cables will be non-pinned. Cassettes add an interesting wrench in the cogs. It looks like most, if not all cassettes have pinned MPO connectors. The best way to get inexpensive fiber cables is to reach out to local contractors or excess warehouses. They carry quality items that have been ordered but left unused. I asked @Patrick this same question and that's his advice, including the following: look for ones that have longer/more fibers than what you need. You will get to know fiber SKU nomenclature very well. Commscope is an excellent vendor because their datasheets tell you exactly how the cables are configured. http://commscope-assetlibrary.com/w...mmScope-Fiber-Product-Catalog-Apr.2020-EN.pdf

Properly testing requires very expensive equipment and your best bet is to get an inexpensive optical (the kind you look into a viewfinder, not ones with a digital screen) microscope. The best practice is after you remove the dust cover--the cover is only there to protect the fiber from getting scratched, not contaminated by particles--inspect the ends, clean if necessary, then reinspect. Repeat if necessary. Here even with inexpensive scopes, the adapter/caps will cost a lot of money. Many come with caps for MM SC/LC simplex cables. MPO adapters costs more, much more. Needless to say, you need caps for APC or risk damaging them. For example, a generic simplex MM 1.25mm (LC) cap can cost US$25-$100 while an MM MPO can cost $400.

Because of the cost I just plan on cleaning my SM tips with proper solvent and non-lint wipes. There are many types of cleaners. For MPO there are cassettes and pens. Pens are similar to LC/SC pen cleaners where you insert the fiber into a housing and press/click. Cassettes are where you place the end on a wipe window and swipe in the correct direction. Before cleaning you advance the tape and don't reuse old segments. You must have the proper cassette for male vs. female ends or else you risk damaging the alignment pins.

These have been my discoveries and if I've made any errors or if there are better best practices please share!

EDIT: only SM MPO have APC ends; SM SC, LC are available with UPC ends
 
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Scarlet

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Thanks for the link to this guide, it probably kept me from making a mistake that could damage my cables.

I just had another good look at my singlemode trunk cables (male and female ends) and it seems that it is not possible to mate the cables as planned:
Using a Type B Adapter (Key UP / Key UP) would make the two APC MTP Connectors match in the wrong way. I didn't understand this next quoted sentence that has it all written out as simple as possible until I checked this myself:
You don't want to insert APC MPO connectors into a key up to key up adapter or you will damage the ferrules.
So, I can't use a Type B adapter and two Type B singlemode trunk cables to create a connection that would behave like a single Type B singlemode trunk cable.

But I think the following should work:
  • Female / Female Type A singlemode trunk cable
  • Type A Adapter (Key UP / Key DOWN)
  • Male / Female Type B singlemode trunk cable
Is this correct? A combination of any number of Type A components and one Type B cable will behave like a single Type B cable?
 

klui

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It depends on your requirements.

Let's say you want to use OS2 parallel optics connected to QSFP transceivers. You need "a" method B cable end to end. You can do this in a couple of ways using key up to key down adapters, ignoring gender:
  • Method A trunk, 1 method A patch, 1 method B patch
  • Method B trunk, 2 method A patches
  • Method B trunk, 2 method B patches
It appears your design has only LC. If that's true, methods A or B for your trunk will work. LC duplex patch cords' are quite flexible and there are many whose polarity are swappable by design. The question is how much complexity you want to tolerate in your design. If you need to have one end of the trunk using method A and the other method B (using an A trunk) you need to make sure your patch cables are organized properly.
 

Scarlet

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My goal is to keep it as simple as possible, e.g. only one type of LC-LC Patch cable between the Kassettes and the optics. I currently only have LC-LC UPC A-to-B singlemode patch cables and I prefer to keep it that way. The trunk cable in the wall can be Type A or Type B, as long as it is well understood / documented and will probably not be touched very often once installed and the correct Kassettes are placed on either end. BTW: I just checked and the LC connector on the Kassettes I already have is actually UPC :)

I'm currently aiming for 6 pairs of LC connections that will be used for 10G between switches. The singlemode fiber is for the future and I'm happy to learn a few new things in the process.

There will have to be some kind of Adapter / Keystone at one end, as the singlemode trunk cable that is installed now will have to end in a wall box in my future office room. That's why I'm trying to understand my options for adapters, as I will need to use another cable to connect the wall box to a kassette in my office rack. The other end of the singlemode trunk cable will be in the basement right next to my core switch (ICX 6450-48P). All rooms will have at least two copper runs to that switch, the fiber in the office is just an extra to play with :)

At some point I will probably need to draw a network diagram to still understand in ten years what I'm installing right now.
 

klui

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There are a few types of MPO cassettes. You already know about the breakout ones.

There are also coupler modules. Others allow you to use the dark fiber of an MPO-12 from a 24+ fiber trunk, splitting every 2 MPO-12s to 3 MPO-8s. Some vendors let you reverse MM polarities.

In the data center, there are ones designed for leaf-and-spline topologies, using one cassette to do the work of 2, eliminating the interconnects. Finally there are tap cassettes used for debugging.

Instead of cassettes, you can also get preterminated fanout cables that directly convert MPO to LC, SC, .... If you have a single MPO my opinion is do what you're doing: terminate to keystone. Then attach a simple MPO to LC fanout cable and protect the unused fibers in an enclosure. Here cassettes definitely help with cable management but that's an added cost and complexity.

I originally wanted to just terminate my fibers to keystones but because I purchased 24+ MPO trunks they should be installed in an enclosure. Other rooms won't get any use and I will pull only 1 MPO cable and terminate to keystones.
 

Scarlet

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After waiting for another shipment from China to Europe I finally did some more tests.

Testing was done using two of my ICX 6450 switches (thanks to the brocade megathread) in a stacking configuration using one SFP+ module per switch. The "testing" consisted of waiting for the stack to re-form and checking if the link came up as "10G Full" after plugging in singlemode patch cables to different ports on the cassettes. The purpose of the test is to check if all fibers in the trunk cables "light up". This is also what I'll do again once the cable is in conduit in the house. I'm happy to take suggestions for more / better testing methods.

Test_Switch_Stack_48P_24P_s.jpg

Test Setup 1:
  • 10GBASE-LR SFP+ module
  • Singlemode Patch Cable (LC UPC to LC UPC, A to B)
  • Cassette #1: Type A
  • MTP-12 Trunk cable Type A (Female to Female)
  • Cassette #2: Type AF
  • Singlemode Patch Cable (LC UPC to LC UPC, A to B)
  • 10GBASE-LR SFP+ module
In this setup the port pair 1/2 of Cassette #1 matches port pair 1/2 of Cassette #2, pair 3/4 matches 3/4 and so on (see images).
Box_A-Trunk_A-Box_AF_01_02_s.jpgBox_A-Trunk_A-Box_AF_03_04_s.jpgBox_A-Trunk_A-Box_AF_05_06_s.jpgBox_A-Trunk_A-Box_AF_07_08_s.jpgBox_A-Trunk_A-Box_AF_09_10_s.jpgBox_A-Trunk_A-Box_AF_11_12_s.jpg

Test Setup 2:
  • 10GBASE-LR SFP+ module
  • Singlemode Patch Cable (LC UPC to LC UPC, A to B)
  • Cassette #1: Type A
  • MTP-12 Trunk cable Type A (Female to Female)
  • MTP-12 Adapter Type A (Key Up to Down)
  • MTP-12 Trunk cable Type B (Male to Female)
  • Cassette #2: Type A
  • Singlemode Patch Cable (LC UPC to LC UPC, A to B)
  • 10GBASE-LR SFP+ module
The purpose of this second test was to test the Type A adapter, and if the adapter with flanges would fit my keystone module. I used a Type B cable here because this was the only Male to Female cable I had available. The adapter does not come with the keystone module, but I kept it in the keystone for the photo.

In this setup port pair 1/2 of Cassette #1 matches port pair 11/12 of Cassette #2, pair 3/4 matches 9/10 and so on (see image)
Box_A-Trunk_A_Adapter_A_Trunk_B_Box_A_s.jpg
 
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klui

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Typical FS topologies are documented at https://img-en.fs.com/file/datasheet/fhd-mpo-cassettes-datasheet.pdf. It's interesting FS has so many types of cassettes.

I am confused by your nomenclature of patch cord "A to A; A to B." Methods describe both ends. So I take "A to A" straight through/method A; "A to B" meaning universal/method B.

Instead of FS, I purchased Corning Edge. They only have types A and B cassettes. Unfortunately I'm still awaiting for parts/tools and I'm not ready to test.
 
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Scarlet

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I'm going with FS terminology, as this is what is readily available here. Most items I can get next day, shipping from China is also quite fast if they don't have to custom build something - like any MTP cable with a male end.

Thanks for the link to the cassette datasheet, that's one I have not yet found.

I think it would be possible to use only Type A cassettes from them, but then you would have to use different patch cables (method A or "A to A" and method B or "A to B") on each end, and I'd rather have only one type of patch cable. So I'm sticking with patch cable "A to B" and the things that I only install one time like the cassettes and the trunk cables have to support this decision.
 

jabuzzard

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Mar 22, 2021
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CAT.7A cabling ist just for the larger diameter (AWG 22) of the copper for PoE+.
That is factually incorrect. Both Cat7a and Cat8 have each pair individually screened. If you don't terminate the cable with GC45 or Tera connectors to properly terminate what are now a bunch of twinax cables then you will make things from an electrical perspective worse over Cat6a. Probably much worse. That said at 1Gbps you will probably get away with it because you are likely to be nowhere near the 90m/300ft cabling limit. At 10Gbps your mileage will vary a lot more.

Given there there is no network equipment for sale that has appropriate CG45 or Tera connectors, then the use of Cat7a or Cat8 is for the gullible and uniformed only. On top of that given that it is utterly useless from a practical perspective it is from an environmental perspective a complete disaster.

My take is that we will never see 40GBaseT in any devices for general sale ever. We might see some sort of twisted pair cabling for 25Gbps Ethernet but it will be many years from now. Even 10GBaseT is as rare and probably accounts for a small percentage of the total number of 10Gbps ports ever shipped. Over the hundreds of 10Gbps ports I have, not a single one is 10GBaseT. If anything ever did present itself with such a port my first port of call would be to change the adaptor to one with SFP+ slots. If that was not possible there would an a stream of profanities while I held my nose and purchased a 10GBaseT SFP+ noting that one is more expensive than two single mode SFP+'s and a 30m length of single mode cable! Compared to a DAC it is just horrible.