50 μm and 62.5 μm Fiber

[Michael]

Hello all,

 

Is there anyway of telling the difference between 50 μm and 62.5 μm fiber? I realise that 62.5 μm is a lot more common, but it's recommended to use the same type throughout a network.

 

What happens if say you have 62.5 μm in the walls, yet you use 50 μm from the fiber patch panel to a switch for example?

[LosOjos]

To be honest, I would have thought the only difference it would make would be how efficiently it carries the signal, I remember reading somewhere that finer cable carries the signal better than thicker cable. I suppose that if you tried to pass the signal from a very thick cable (>150um) in to a finer cable (<80um) then you could have problems with signal loss, but a difference of 12.5um just seems insignificant... I have no experience to back that up though I'm afraid.

 

More info here: Optical fiber - Wikipedia, the free encyclopedia (particularly here: File:Optical fiber types.svg - Wikipedia, the free encyclopedia)

 

Just found this site that explains that passing smaller to larger is fine, but larger to smaller causes data loss: Power Penalty For Mixing 50/125 And 62.5/125 Fibers

[Michael]

Thanks for that, much appreciated.

 

I love this one liner: New TIA standards call for color coding cables and patch panels to prevent mixups.

 

You don't say comes to mind as it's an absolute nightmare! The problem I have though is without knowing whether 50 μm or 62.5 μm is in the walls, what do I use to go from the fiber patch panel into the switch?

 

At the moment 10/100 fiber media converters are used, however I want to change this and patch it in using an ST/LC cable into an SX transceiver operating at gigabit.

[localzuk]

Thanks for that, much appreciated.

 

I love this one liner: New TIA standards call for color coding cables and patch panels to prevent mixups.

 

You don't say comes to mind as it's an absolute nightmare! The problem I have though is without knowing whether 50 μm or 62.5 μm is in the walls, what do I use to go from the fiber patch panel into the switch?

 

At the moment 10/100 fiber media converters are used, however I want to change this and patch it in using an ST/LC cable into an SX transceiver operating at gigabit.

 

Your existing patch leads should have details on them, failing that look at the sleeve of the fibre itself, it should have markings on it. I've yet to come across a fibre that couldn't be identified this way.

[steveg]

Most cables should have it written on it, if not might be worth looking up the spec of the exisiting media convertor, - it may only work with one type of cable, so you can fairly safely assume thats the type of cable being used.

 

Steve

[SYNACK]

Yes look at the outside of the cable. If you use different sized stuff for patch and run you get terrible loss and far more errors. 62.5 is the older standard and will happily handle 1GB/s, 50 micron is usually OM3 and can support 10GB.

[Michael]

Thinking about it also, (worse case scenario), is I could go by the date of when the fiber was installed. When did 50 μm start to be available? I'm guessing 62.5 μm has been around for a good 15 years mainstream at least.

[steveg]

50/125 was invented in the 70's and started being commonly used in the 90's so that may not help.

 

Steve

[SYNACK]

Thinking about it also, (worse case scenario), is I could go by the date of when the fiber was installed. When did 50 μm start to be available? I'm guessing 62.5 μm has been around for a good 15 years mainstream at least.

 

If it is older than 6-8 years old and uses multimode transcivers/modules then it is almost certainly 62.5 but the only way to be certain would be to get a look at the sheith, are their no accessable runs? Quite often there are bits that go through that wall mount capping stuff with a removable lid that you can pry off to get a better look then just click back on afterwards, it should also be on the current patch leads as above which is proably the easiest.

[plexer]

Wall mount capping stuff = pvc trunking.

 

Ben

[Michael]

I will take a closer look later on in the week and report back. Thanks for all your help guys, much appreciated

[SYNACK]

Wall mount capping stuff = pvc trunking.

 

Ben

 

Thanks for the translation, if we were talking in cisco language it is also called decorative wall mount but personally I do not find it overly decorative

[HarryMonkey]

What happens if say you have 62.5 μm in the walls, yet you use 50 μm from the fiber patch panel to a switch for example?

 

62.5/125 vs. 50/125 Multimode Information

[Avalon]

just to add to stevenewman's post:

 

I have had this before and found a 62.5 micron fibre on quite a long run and then a 50 micron patch lead to connect to the switch and produced a huge ammount of loss. This would cause a noticeable reduction in performance ...

[m25man]

Check this previous thread, http://www.edugeek.net/forums/general-chat/73047-determing-speed-fibre.html#post651613

 

You will find the link to my uploaded training manual.

 

Mismatched patch leads will produce a 3db insertion loss (approximately half of the power available at that point)

Anything greater than 6db in a given segment (between repeaters) will result in a blackout (the point at which the receiver is unable to distinguish between on/off or 0 and 1)

Such losses are often mitigated by the use of Long Range Modules over short cable distances.

[maniac]

It's not a good idea to mix different types of fibre as you will get loss. However it will work, but you may notice a performance drop. I recall having no choise but to mix fibres at one school I worked at on account of not being able to get hold of patch leads with the correct fitting on in the correct size when we needed them. They were eventually replaced with the right ones, but for the short time they were miss-matched they worked fine, the switch just gumbled every now and then about lost packets or alignment errors.

 

Mike.

[crt404]

Agree with Mike above. You will notice (if you put an OTDR on it) a huge dB loss on signal, but for short fibre runs (less than a Km) you won't have any problems.

[Michael]

Thanks to you all, I managed to find a patch lead I could read and it is 50 μm There are several cabinets however, so I'm going to check them all as there is currently a lot of slowdown on this network I'm looking at...

[wizzard]

Thanks to you all, I managed to find a patch lead I could read and it is 50 μm There are several cabinets however, so I'm going to check them all as there is currently a lot of slowdown on this network I'm looking at...

 

The cabs don't look like spaghetti junction do they or are they nice and neat?

[Michael]

I'd probably say somewhere in the middle to be honest, I've seen a lot worse!

[fr4j0]

2c

 

Patch Cords as a General Rule of thumb:- remembering that manufacturers like to have their 'type/colour' bah!

 

Grey - 62.5/125 - OM1

Orange - 50/125 OM2 & Light Blue/Yellow OM3

Yellow - 8/125 OS1

 

If you hear people talk the talk about OM4 and OS2 - their just a finite grade of fibre that is increasing in popularity due to salesmen and their toys, just gives more bandwidth/headroom. More cash for not that much.

 

General Connector Types:-

 

ST - good mechanical connection generally 62.5 OM1

SC - grey is 62.5 OM1 -- blue is 50/125 OM2/OM3 -- although installers don't always play by the book ( a little more expensive for blue fibre couplers in the panels, I've also seen panels to be OM2/3 and have grey connectors)

 

LC - grey 50/125 OM2 -- blue OM3 - small and type used in miniGbics

 

SC/LC/FCPC etc - 8/125 OS1 (ST isn't the best for 8/125 - too much movement on the connector heads)

 

Also: -

 

Go for 50/125 10Gig (450 ish meters) if your installing LAN and/or if you can afford additional hardware cost 8/125 for LAN up to 2km

 

WAN is generally 8/125 for long haul (or short haul); WAN @10Gig it's the hardware that's the killer

 

62.5/125 has seen it's days and is heading for retirement

 

Mixing Fibre Types

 

Not a great idea - as seen from the links others have posted - cause mass reflections and can grind a network to a snails pace or halt due to re-transmission of failed packets.

[localzuk]

Those should only be used as a very rough guide. My fibres are OM3 with ST connectors and orange ST-LC cables, with beige connectors. So basically ignoring all the guides you mentioned.

[john]

As for mixing fibres, try to standardise your site on one type otherwise you end up with piles of spares of differing types. We have mainly used OM1 fibre due to the length of runs being small, however our 2nd campus across the road will be linked with OM3 to give us the 10 gig connection speed, that link will be the OM3 link and marked up as such and be OM3 from end to end so mixing that way is fine, its just don't mix the types in the same link.