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Single-mode fiber pitfalls?

her209

her209

No Lifer
We're getting ready to do a massive rollout of single fiber where I work. Any pitfalls that I should be on the lookout for when working with single-mode fiber as compared to multi-mode? Current infrastructure is 62.5 micron MMF.

I'm talking about optics, patch cables, bend radius, LIU-to-LIU jumpering, etc.
 
There is more to SM than we could really tell you here. Why are you choosing it to begin with would be the first question.

That usually drives the need and all the expense and extra work SM calls for.
 
Pitfalls are more expensive and depending on your gear, you may need to attenuate some links.
 
Because SM fiber is so much smaller in diameter (8.3 micron), cleanliness of the connectors is critical.

There are also safety issues, as all emissions are invisible, and nearly all of them can permanently damage the eye. Warning signs are suggested, safety and operational classes are suggested, covers on all unused ports or ends is mandatory ... both to protect from accidental exposure and to keep it clean. Some shops issue laser glasses / goggles that filter the wavelengths in use for maximum safety (Lab Safety is now Grainger ... that's where I got mine: http://www.grainger.com/Grainger/wwg/search.shtml?op=search&N=25987&in_dim_search=1 ).

SM cable is more susceptible to loss from bending, and more likely to break if stretched. It is a royal pain to terminate. Alignment is critical (because it's only ~8 micron) ... don't cheap-out on panels / WICs, jumpers, or termination.
 
How many miles are you running connections? What is the business need for SM? The GBICs for SM are really costly and dangerous to work with without laser lenses etc.

Considering MM is good to 100GB at 150 meters (OM4) the only need for SM would be long haul intrabuilding connections.
 
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The others have pretty much covered it, but let me share what we do:
We always scope & clean the fiber ends before insertion.
We've also had to put attenuators on our ONS gear because the light came in too hot.
Not sure if you'll run DWDM, but taking a basic optical course helps.
 
We're actually getting a hybrid SMF/MMF fiber cable. One reason why we're going with SMF is due to distance. We have buildings that are close or past 550m when measuring the length of the run.

Second reason is to be able to run 10Gbps interconnections between the different switch stacks if we need to.
 
Just so you know we have 10G links between our distro & core switches over MMF, and it works just fine.
 
The vendor that we buy our optics from have modules that they say will run 10Gbps up to 10km. But the price difference is minimal between that one and the SMF module that does up to the same distance.
 
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