Fiber questions Single mode cable Blue vs. Yellow.

[cknipe]

Does anyone know the difference between Polarization Maintaining Single-mode fiber (blue cable) and just normal single mode fiber (yellow cable).

I am installing some switches across someone else's fiber job. At site A they left the Blue style single mode fiber hanging...on the other side they left the yellow style single mode fiber.

We're not getting a link between the two switch and the fiber guy says the from patch panel to patch panel the fiber is clean.

Does anyone know does the fiber type have to be exactly the same all the way through?

 

[RikRodgers]

I hate to ask, but what color blue?

The light colored blue is typically 10G multimode, the dark blue is typically tight bend (ack, it's been a long day. The proper nomenclature isn't coming to mind) single mode.

The best way to be sure is to check the part number on both cables, read the specs for each, and make sure they have the same core diameter. Not all single mode fibers are created equal. If the core size is the same, you should be ok. Just clean 'em, and plug 'em back in.

Obviously, if one is multimode, you'll want to replace it.

 

[cknipe]

its the dark blue I know its single mode but I also know its this special "Polarization Maintaining Single-mode " type of fiber whereas the Yellow single mode fiber is the TIA standard for single mode.

All I know is that someone else was responsible for providing the fiber and im pulling my hair out.

I'm actually going to have another yellow cable tomorrow so i'll update the forum if no one has answered by then.

 

[RikRodgers]

That MAY work for you, but to be sure look up the associated part numbers. Especially for speeds of 10G and higher, core size matching matters.

 

[NECPBXtech30]

am i missing something? are the 2 fiber spliced together? or is there a transition point in the middle? why are there 2 different fiber types if it is one run? I agree that verifying part numbers is important. The core diameter should be 8.3 microns (i think) on both fiber types. When you say it is hanging, is that the point to point fiber or is it a duplex fiber jumper that is hanging?

"However beautiful the strategy, you should occasionally look at the results." Sir Winston Churchill

 

[cknipe]

theres a fiber patch panel in between the two sets of cables.

 

[NECPBXtech30]

If you are sure they are both single mode fiber go to the patch panel between them and test each segment seperately with your switches. Have you seen the verified test results or just been told about them?

"However beautiful the strategy, you should occasionally look at the results." Sir Winston Churchill

 

[Mugsiensedgwick]

This may or may not help, but I recall being told that one should never use a patch fiber less than 10'.
Does anyone else recall such a rule?

 

[RikRodgers]

Nope.

You may be thinking about copper. Most testers won't certify a run less than 9'.

I've never heard of such a rule for fiber.

Standard installation practice for fiber to the home is standard sm fiber (yellow jacket), through splitters, and patched at the user's site using reduced bend radius sm (dark blue jacket) cables, due to the small size of the NID.

Core size matters, though, and any patch cord can be made to attenuate, or pad signal. That's why I'm emphasizing checking the part number on the patch cords if you didn't order them yourself, so you know exactly what you're dealing with.

 

[NECPBXtech30]

Verify the part numbers and ask to see the test results. Any good tech will have saved results or give the customer a copy of the results.

"However beautiful the strategy, you should occasionally look at the results." Sir Winston Churchill

 

[mikeydidit]

As RikRodgers has mentioned, the Specialty colors are for extreme high speed applications. These cables are mechanically polished and some are even sold as just tails. By this I mean the connectors are on to a x number length of cable(s). Then you fusion slice the tails to your cable for very close tolerances.

At just over a mile away from our CO, we have to use a 10 db attenuator because the signal is too hot. This is to our 100 gig connection. The other applications we run 1 gig on (inside fiber back bone) regular "yellow" patch cables.



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