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These are just some ramblings on some "newish" fiber network connectors.  These caught me by surprise. 

I'm accustomed to fiber network cables where you have one pair (either single mode or multi mode), where one strand is transmit and the other is receive.  The connectors on each end is relatively standard, ST, SC, LC, etc.

Well, in getting bids for some new networking, I was getting 40 & 100 Gig network switches that used MPO / MPT connections.  These connectors are a bit different.  Each end of the MPO / MPT connector uses either 8, 12, 16, 24, or more fibers!!!!  This obviously ups the fiber strand count rather significantly.  Under the old (used 2 fiber strands), a 12 or a 24 strand cable was usually more than enough for several devices and plenty of spares for growth. 

I haven't been able to get (for a reasonable price) a copy of this new spec (https://en.wikipedia.org/wiki/100_Gigabit_Ethernet) , but it's geared towards 40 Gig and up network speeds.  At a very simplistic level, a 40G link uses 4 strands on one side for transmit (4 @ 10G each) and 4 strands on the other side for receive (again, 4 @ 10G). 

100G can work the same way on a 12 strand cable, but uses 4 @ 25G ----- OR ------ uses a 24 strand cable (2 rows of 12 strands) and then one of the rows us transmit (10 @ 10G) and the other row for receive (10 @ 10G).  The outer strands on each row are not used.

The *wonderful* part of this is that these spaces are still relatively new and various manufacturers have adopted their own interpretation on their specific implementation.

It appears the days of old where you would run the highest grate of fiber you could afford (and the optics for each end), and you were somewhat "future proofed".  Now, it's a bit more problematic.

In my case, I can only afford to buy 40G optics, but want the switches and the fiber to be ready to handle faster speeds (50, 100, 400) in the future by merely swapping out the optics 9at the prices came down.

Just some musings.....

Jim

A little background ...

In my Denver campus / offices, we do a lot of HD (and 4k, 5k, and 8k) video editing.  I have an MDF in each of my two buildings (separated by about 150 meters (which is why I can't use Copper cable to interconnect the two - the distance is too long).  My main editing storage device (Isilon NAS) is in one of the buildings, but the computers needing access that storage are in both buildings.

Over the last 18 years (in this job) I've been organically (gads, I hate that word) expanding the network on an almost zero budget.  The ability for all users in both buildings to be able to access the raw video has become problematic over the last couple of years due to the file size and "density".  The existing fiber mishmash infrastructure lets me get up to about 5 - 10 G speeds.

It's now time to increase the capabilities of my physical cable plant / infrastructure so these higher resolution (and much larger) files.  This new infrastructure will be able to (eventually) enable speeds of up to 400 G (once the $$ for the optics comes down).  Initially, I plan to use 40 G optics - and probably "bond" (LACP / MLAG) them together for (a little under) 80 G speeds.  Increasing the throughput / speed of the main fiber optic network connections is crucial to being able to remove the slowness and problems of my existing infrastructure.

I've been getting quotes from vendors for this project over the last few months.  As a final "fact check" for any faulty assumptions I may have had and to make sure all the pieces & parts are going to "fit" together, I "discovered" my need to use MPO connectors.  This of this as an assembly - will bolt A go into hole B and use nut C to secure them together.    Due to these MPO connections, I had to go back to my fiber contractors (I'm not doing this myself like I have in the past) and have them re-quote for pulling several 144 strand cables (rather than the 24 or 48 I had originally asked for-  before I understood MPO connector needs).

There's a ton of other BS details to take into consideration with these damned MPO connectors, one of which is the form factor could change for the faster speeds.

Anyway, hope that adds some clarity to my ramblings (that's why I'm not a writer such as the great and powerful Gorm).......