Fibre testing Kit

[spacehopper]

hi,

 

we are experiencing some intermittent issues with our network.. and think it could in part be down to some ageing (approaching 15 years old in some places) Fibre runs..

 

I dont know much about fibre and havent ever installed any (apart from connecting patch cables to switches) or tested it before..

 

The fibre was mostly all installed before i started here by the then technicians (who have now all left..) who all got sent on a fibre course..

 

As far as i am aware it is all multi Mode fibre, with 95% ST connectors (one cab has SC for some reason..) in the network cabinets.. these are then connected to the switches via an SC to LC fibre patch cable to the mini gbic modules in the switches..

 

does anyone have any reccomendations for equipment either to buy or hire if it is super expensive.) to test the condition of the fibre runs?

 

thanks!

[Boredguy]

We found a local electicial installation company that do fibre installation and they duely tested the run we had put in for them to terminate, so you might find someone like that in your area.

[Sagima]

Your switches may show the strength of the fibre connection or at least have a fibre diagnostics option

[spacehopper]

I have checked the main switch and it only has a ping test on it as far as i can see..

[Sagima]

What model are they?

[spacehopper]

main switch is an ageing HP 5406ZL

 

edge switches are mostly (also ageing) HP2626 and HP2650

[3s-gtech]

I was informed by one of our suppliers, who tested our existing fibre runs, that some of the older stuff is pretty good quality and will continue to work well, at least up to 1Gb speeds. Their audit of all of our fibre was only a few hundred quid.

[ITGURU]

I've never known fibre to degrade or be intermittent. Only issues we've ever had with fibre is contractors breaking the cable or rodents biting through it because the original cable was never armoured.

Just run some constant ping tests between the switches at each end of the link, if any timeouts appear or the switch logs are reporting link up/link down errors then that can most likely either be bad fibre or fibre module issues.

[forkies]

If the cable has degraded over time which is possible, especially with old fibre cable where the cable cannot stand a wide range of temperatures, or is in sunlight and effected by UV it can expose the inner fibre strands to low levels of ambient light which affects the transmissions across it.

 

Effectively we were told to replace fibre cabling if it is 6-8 years old by more than one specialist.

[ITGURU]

If the cable has degraded over time which is possible, especially with old fibre cable where the cable cannot stand a wide range of temperatures, or is in sunlight and effected by UV it can expose the inner fibre strands to low levels of ambient light which affects the transmissions across it.

 

Effectively we were told to replace fibre cabling if it is 6-8 years old by more than one specialist.

 

Crickey that would be an expensive job for us on a 10gb backbone. We've had fibre runs outside for 13 years and still run error free. Would need to be some serious harsh environments to cause any issues although one did get chauffeured on a catenary wire once and eventually split due to high winds.

[m25man]

Effectively we were told to replace fibre cabling if it is 6-8 years old by more than one specialist.

 

That's interesting, as Corning one of the worlds largest producers of optical polymers say different.

http://www.corning.com/media/worldwide/coc/documents/Fiber/RC-%20White%20Papers/WP5082%203-31-2016.pdf

 

Our cabling contractors whom we work with on all of our infrastructure projects offer a 25 Year guarantee on all installations end to end from all of the leading fibre manufacturers.

All installation engineers have their own regularly calibrated Fusion splicers and Fluke DTX testers.

 

https://www.brand-rex.co.uk/support/warranty-program

 

If your installers are not offering these levels of service, verification and guarantees then your probably getting exactly what your paying for.

 

When tested, most of the failed cables we come across are normally due to insertion losses, Bad Terminations, Rodent or Physical damage.

 

Once installed, unless disturbed a fibre will probably be good until made redundant through technological advances.

 

We have recently used TDR to measure 20 yr old OM1 only to find that it was more than capable of passing 1GB @ 850nm over its serviceable length.

 

In most cases it's down to the overall length of the run, if it's the right diameter or mode and the terminations.

A quick clean with some IPA and a swab at each end you've got -3db loss back and the links is up again!

 

Another common reason for link loss failure are trancievers, there are big differences between LED or Laser based transceiver modules and you need to be careful when matching devices at each end of a run.

 

A high quality laser optic on an HP switch at one end of a 200m link may not even want to see a cheap LED module on a TP-Link at the other!

 

All SFP's are NOT the same, which is why I have several types handy in my toolkit that I can swap in my testers so I can match the clients configurations.

 

I have to maintain many miles of Fibre Optic runs at some of our sites of which many are in much harsher environments than most schools, so there's not much I've not had to deal with when it comes to fibre.

[forkies]

That's interesting, as Corning one of the worlds largest producers of optical polymers say different.]

 

Appologies, I was talking in respect to the cable we had previous... the cable was deteriorated and all external runs broke when temp dropped outside on our external runs. We came in next day to all external fibre runs broken (this was 5 years ago) and the fibre was about 10 years old at that point, probably not fit for purpose on installation.

 

Our new fibre is guaranteed, they were talking in respect to cabling that was installed up to 8 years prior, as its temperature range on the cable was insufficient for the cold weather we experienced and in terms of future proofing with 10gb capable fibre.

 

Although I have had a cable prior to that big freeze that was degraded in sunlight and moss, exposing the inside of the cable. Hence why I referred to this.

 

It is probably a good time to get cabling replaced with OM4 armoured cabling installed if you are thinking of replacing it and getting it future proofed.

[synaesthesia]

Recently replaced a fiber run with cat6 at one of my primaries. Whoever fitted the fiber originally ran it over the roof and only fitted standard, unarmored cable. Connection was slow but reliable, and when they had the roof replaced this summer the site super and myself hopped up on the roof to see about re-routing it. We found that the cable was crap, UV damaged, frayed on every bend it took and better still at one point it hung over a ledge and the roof felt had sandpapered it down. By absolute sheer fluke, it had gone through the inner and outer sheaths and 6 out of 8 of the fibers.

The remaining pair connected and indeed holding the whole thing together was the pair being used. Decided with a tight budget and a DIY perspective with no fiber training, and only a 60m run to replace it with armored, UV resistant cat6 routed properly round the roof to avoid such rubbing in the first place!

[XiJ]

Funnily enough I have a Job replacing a fibre link tomorrow with some external copper.

We've tested everything to know it's not the sfp / switches. With school in a tight budget and the length of cable required we've chosen go use cat5e to replace the fibre.

 

The fact the fibre was converted using external transceiver / receivers on a 10/100 Ethernet link means the copper link will now actually be much faster!