I am having issues with speeds (internet/network). Server, modem and fire wall in on building and connected by a 400 ft of cat5 cable. Cable is running over head and tru pvc conduit. I know it should be replaced with fiber optic cable however I am green when it come to fiber optics and to connect to cat5 at the switches. What would be a good solution on how to get this done?

  • Is it really 400 feet? Your about 70 feet past the accepted maximum length of Ethernet over cat5. – longneck Aug 25 '13 at 20:13
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    @longneck Which is why I think getting a fiber run is now on the table. – sysadmin1138 Aug 25 '13 at 20:20
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    400 ft is about 120 meters in SI. – Uwe Keim Aug 26 '13 at 3:38

Buy a pre-made multimode fiber cable in the appropriate length with LC connectors . The cable should be rated for pulling. The nice thing about LC connectors are you can fit them through conduit. Just don't pull by the connectors.

Make sure your conduit does not have any right angles in it and any bends should have at least a 6 inch radius.

Get yourself a bottle of wire pulling lubricant. Be generous.

If your switches don't have LC fiber connectors built in, buy SFP transceivers (if you switch has SFP ports) or media converters.

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    One missing detail is the class of fibre; for 400ft it shouldn't matter too much, although if you think you might ever possibly want/need this link to be 10gbit, go with OM3 or higher. Make sure you don't mix the fibre classes. For example, if you terminate the fibre to a patch panel instead of plugging it directly to the switch/media converter, make sure you use a matching class of patch cable to connect the patch panel to the switch/MC. – fukawi2 Aug 26 '13 at 0:15
  • Good call on the OM3. – longneck Aug 26 '13 at 2:05
  • I don't know what class the Army uses, but when I was in the Signal Corps, we had SPOOLS of fiber that we pulled all over the place, right angles, left angles, you got it. Left it outside for days, buried it, no conduit. Lasted a year in Iraq. No wire lubricant at all. – Brian May 29 '14 at 10:27
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    @Brian Class refers to the optical properties of the cable, not the construction of the cable covering. The spools of cable you are talking about were probably rated for direct burial and UV exposure and armored with built-in minimum bend radius protection. The cable I am suggesting is much less expensive and designed to be run through appropriate conduit. – longneck May 29 '14 at 13:27

Personally, if you're green with fiber optic I would forget about doing that yourself, either get someone in or leave it.
400ft is over the maximum length of cat5 standard (max 100m ~330ft), so the simple solution if it's available to you is to put a suitable hub or switch in the middle. Of course if this is through walls and conduits you may not find a suitable place where it's available for maintenance, don't just seal it in the wall...
Another option is to use ATM or some other suitable long distance system, but ethernet over cat5 will cause you issues.

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    Fiber, at least in this instance is not all that complicated. It is easy to find pre-terminated fiber in all sorts of lengths. Combine that with a couple of media converters (or SFPs if the switch support them), and Bob's your uncle. – EEAA Aug 25 '13 at 20:35

Fiber is somewhat fragile, and it can break (and be rendered useless) if it is subjected to too much strain.

You can’t just pull it over a very long length without taping it to something else (that you’ll also be pulling) at regular intervals to relieve the strain.

You can buy special, relatively inexpensive network pull string for the purpose, or if you don’t have any of that you can use any high tensile strength string (not twine, it breaks too easily, and avoid stretchy string because that sort of defeats the purpose – you want the string to help pull the fiber, not the other way around).

The fiber I’ve seen needs to be inside something to protect it (no direct burial) – you can use cheap irrigation pipe for the purpose, as long as it’s large enough for the connectors at the ends to pull through (don’t try to be thrifty and undersize the pipe, but at the same time realize that fiber with the small LC connectors has plenty of room inside a standard one inch irrigation pipe, assuming you’re not pulling several multiple fiber pairs or other wires and cables).

Also, you should use pulling lubricant on long pulls to prevent damage to the fiber jacket.

(Information taken from fiberstore.com)


As said before: Order preconfigured OM3/OM4 cabling in the fitting length and buy a pair of SFP (SX-LX) transceivers specified to fit your switches (don't go for cheap "compatible" ones, better stick to the manufactorers.

Use good cabling with a thick and strong outer casing and be careful not to either bend or pull too much on installing (fibre is more liable to break than copper). And make sure you have some extra pairs of fibre for either swapping out defective ones or further expansions. Won't make too much of a difference, and will be very very much cheaper than having to run a new cable some time later - labour costs can be twice or more than the cables itself...



Longneck's suggestion of a Multi-Mode lead with LC connectors is sound but you could also consider your options for expansion later and install a higher capacity cable, maybe try something with MTP/MPO connections (12/24 core) with a plug-n-play FOBOT at each end. Definitely go with Laser optimised OM3 or OM4.

Whichever option you go with make sure you clean before you connect. Even if you just use some of the disposable fibre wipes. One of the biggest causes of fibre issues is dirty mating surfaces.


Before going through the effort and expense of running fiber, you might try using an Ethernet extender like the ones shown here:


I've had excellent success with the above company. If you need to do gigE, the above won't work. But if you're happy with 100mbps (or close to it), you should be good.

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