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Discussion Starter #1
First time to design fiber cable so I’m lost.

I have to distribute cat6 cable from telecom room to 3 office furniture places for voice/data use.

my question is if I use 4 strand multi mode, does that mean I can use the for 4 outlet?
 

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Don't quote me, but if you're saying use 4 pair cable only 1 outlet per cable. Sounds wasteful, but most IT guys say it is that.
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Elechicken!
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So you are saying it is possible with 4 strand cable to feed 4 office seats
Possible? Yes. Advisable? No.

I'd plan for 2 fibers per drop, one for TX and one for RX, basically one for sending and one for receiving. So if you need 4 drops, you need 8 fibers. TX and RX can be done over 1 fiber but its not popular for data inside a building.
 

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Discussion Starter #5 (Edited)
Possible? Yes. Advisable? No.

I'd plan for 2 fibers per drop, one for TX and one for RX, basically one for sending and one for receiving. So if you need 4 drops, you need 8 fibers. TX and RX can be done over 1 fiber but its not popular for data inside a building.
I see. Thank you
 

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It gets more complicated. Multi mode is cheap but permanently limited to roughly 1 GBPs and I think 500 meters or 2 km on paper at 100 Mbps but realistically it’s more like 4-5 km. If you later just splice them or use a coupler and you’re already at the distance limit you’re done. Then you must pass through a switch. There are several different connectors too but these days mostly the mini GBICs need LC style connectors.

With single mode you can go 40 km. The only limitation is the quality (and price) of the lasers. The big difference here is that you need much better more accurate terminations. Frankly just pay someone about $50-100 per termination and be done with it if you don’t do this all the time.

Then we get into bandwidth tricks. To begin with you can simply use switches that will combine multiple channels into a single higher bandwidth channel (bonding). But more interesting is DWDM and CWDM. In a multi mode fiber the light bounces around what amounts to a “fat pipe”. There are multiple different paths so the light spreads out as it travels. In single mode fiber there is only one path so it does not spread. But it works with different light colors. So you can buy transceivers of different colors and a connector with a prism to fit up to 8 transceivers onto the same pair of fibers. Or with much more money use a special transceiver that uses multiple frequencies and more bandwidth called DWDM.

Finally don’t forget that with most fibers it is difficult to intercept the signals on it and can be fairly expensive to pull new ones. You can also say run a control or video or security system alongside the existing IT network and be truly 100% isolated on a totally separate LAN in the future if needed.

Finally consider fiber rings. So say one of your sites becomes the data center or customer facing web site. Going down simply isn’t an option, even for maintenance. So a cheap method is use two ports per switch arranged in a “ring” again with a pair of fibers. It does not have to be laid out exactly as a physical ring as long as it is all connected as a ring...some connections may share the same fiber cable. The switch software naturally picks one pair of fibers as the backup link. In this arrangement if any single switch or transceiver or fiber fails the switches swap to the redundant link and everything continues operation without the users even noticing (failover is about 1-2 milliseconds per switch in the ring).

Only reason to mention this is that most of the cost is in the installation labor. If there is any chance of ever needing more bandwidth or distance you should seriously consider either extra fibers which is a small cost or single mode fiber. I can’t tell you how many times I’ve seen people shout themselves in the foot by not putting in extra fibers ahead of time. So count on 2 pair of fibers per destination as a minimum. But more is usually worth it up to a point. That way once it’s in you can make changes and improvements over time without expending labor
 

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I agree with above, 2 fibers per jack with RX/TX on separate fibers. It does not make sense to try to mux/demux for every workstation with the cost of fiber is negligable, the labor is where the cost it.
 

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I guess my question is why are you doing FTTD? There is little to no consumer grade equipment out there that can max out Cat6, barely max out Cat5e. Now if you are doing a bunch of high end video editing off a production server(s) or something like that, perhaps. If you are talking a distance limitation, then your design is incorrect and need to look at where your MDF and IDFs are located.

Now if you want to run fibre from the MDF to a centrally located IDF(s), then all you need is two fibres, pair up to four or six if you need to increase bandwidth. Between an MDF and an IDF, I never run less then six fibres to separate out components, Data, Voice, Security / Alarm, are the most common. If I had POE lighting or other controls then I would add more fibres to separate the networks. The truth is, there is enough room in a single pair of fibre to handle all of that, but the cost is nothing to add, two, four six fibres even if you don't use them.

Cheers
John
 

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The very minimum I pull is 6 strand, perhaps 4 strand to a workstation. I’ve never had a customer complain about too many strands but I have seen them get screwed over too few strands and i’ve seen them ecstatic that they had spent a little extra years ago to find they have the spare strands to implement a solution immediately.
 

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IBEW 6 volts to lightning bolts
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First time to design fiber cable so I’m lost.

I have to distribute cat6 cable from telecom room to 3 office furniture places for voice/data use.

my question is if I use 4 strand multi mode, does that mean I can use the for 4 outlet?
Yes 4 strand fiber matching the diameter of the distribution in the telco closet. Probably 50mn MM Aqua. I’ve only seen pure fiber at desk locations at the AMP facility down in Harrisburg, PA. Most normal business setups now run the voip and computer on one single copper cable at the desk. Unless you are running animation from your desk for Pixar or Blue Sky copper will be fine.


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