Help. - Which is quicker/better

[calwyn]

Hi everyone.

 

Our school has recently been subjected to a couple of IT Audits, one of which was particularly obsessed with infastructure & would like to offer to rewire the whole school.

 

Anyway, one of the things that they have highlighted is that rather than using a one pair 1gb fibre uplink between two key switch locations, we used a pair of trunked copper cables instead. In my mind 2x1gb copper is better than 1X1gb fibre... or am I wrong?

 

The cable run is roughly 40m and although there is an 8 core (50m) fibre run in place we believe that only one pair works, our ex-technician (CNA Certified) advised that the 2x copper would be quicker than 1x fibre. To add to the complications, the fibre currently is terminated with a couple of media converters to present a 1gb cat5 to the switches.

 

So, what do you experts think? (please explain in simple terms)

 

Thanks in advance, Calwyn.

[jamesreedersmith]

In simple terms 2 x 1gb copper is better than 1 x 1gb fibre

 

Copper

Twice the capacaity/bandwidth ( not speed though necessarily)

redundancy in case 1 cable is damaged/fails

[calwyn]

Hi James & thanks for the reply.

 

This is exactly what I though, but the "Experts" who audited our network tell us that I'm wrong.

 

Calwyn

[3s-gtech]

The run fibre may well support 10Gb, where that could be pushing it on copper.

[calwyn]

The run fibre may well support 10Gb, where that could be pushing it on copper.

 

This is true, but that would require extra hardware at the ends. With the current configuration there is no 10Gb hardware.

[mukz]

Is the guys who audited offering to do the work for free? If no tell them to do one.

 

The 2x1 copper is better as james said even though i would always favour 2 fibres.

The fact that there is a media converter also aids your argument that the 2x1 copper is better.

 

Usually these organisations come in and do audits and say this is wrong and that is wrong to earn a few bob

[Blue_Cookeh]

Sounds like fishing for work and that you should make your own decisions. Realistically how often does an interface fail? If someone were to cut the fibre then you could get a company in to splice it or pull a new one with more cores for more redundancy.

 

Also if they're suggesting you switch from 1 fibre to 2 trunked copper and doing so would need a new cable run then WTF are they thinking? If you had to run more cable you should be pulling another multicore fibre cable between cabs.

Edited July 26, 2018 by Blue_Cookeh

[dcwhitworth]

My major concern is your statement that you have eight fibre cores but that only one pair works. That implies to me that there may be degradation / damage to the fibre and that your one fibre connection could be at risk also.

 

Another thing you don't mention is where the network connection is between. If it is between two buildings you definitely should be using fibre not copper, but barring that I could definitely go for the two new copper connections. Two is better than one, new is better than old and your existing fibre connection may have degradation issues.

[Roberto]

I guess I have two concerns here:

 

Firstly, the school should stop accepting "audits" from auditors who have a vested interest in selling you things. I appreciate that's easier said than done if they're getting in the ear of someone high up (I'm basing all this on the phrase "subjected" in your post btw), but there's an obvious conflict of interest if the same people who are identifying needs are the same people selling products to meet those needs...

 

Secondly, what happened to the fibre? This would bother me, it shouldn't simply just fail. As dcwhitworth says, if its between two buildings then you should be using fibre, but in any case if this is a major run and you have no redundancy that's a worry.

 

Beyond that, my only feeling is that future network expansion might be limited depending on what kind of copper you run there. It's possible to push 10Gbe over Cat 6a reasonably enough these days so that would be a reasonable change to make now with room for future expansion but I'd not be impressed if they were quoting Cat 5e.

[dcwhitworth]

I guess I have two concerns here:

 

Firstly, the school should stop accepting "audits" from auditors who have a vested interest in selling you things. I appreciate that's easier said than done if they're getting in the ear of someone high up (I'm basing all this on the phrase "subjected" in your post btw), but there's an obvious conflict of interest if the same people who are identifying needs are the same people selling products to meet those needs...

 

Secondly, what happened to the fibre? This would bother me, it shouldn't simply just fail. As dcwhitworth says, if its between two buildings then you should be using fibre, but in any case if this is a major run and you have no redundancy that's a worry.

 

Beyond that, my only feeling is that future network expansion might be limited depending on what kind of copper you run there. It's possible to push 10Gbe over Cat 6a reasonably enough these days so that would be a reasonable change to make now with room for future expansion but I'd not be impressed if they were quoting Cat 5e.

 

Definitely this.

 

Never skimp on your infrastructure costs, it will come back to bite you. Look to get cabling installed that will support 10Gb even if you have no intention of using it.

[calwyn]

Hi Guys, thanks for all the responses.

 

Just to clarify, the 8 core fibre is the second preterm'd fibre that was pulled in, after there were no working fibres in the first attempt. The reason is "Electricians". Rather than being pulled in by a data cabler, the fibre was pulled in by an electrician. They weren't happy at having to buy a new one (£400 at the time) after breaking the first one.

[dcwhitworth]

Hi Guys, thanks for all the responses.

 

Just to clarify, the 8 core fibre is the second preterm'd fibre that was pulled in, after there were no working fibres in the first attempt. The reason is "Electricians". Rather than being pulled in by a data cabler, the fibre was pulled in by an electrician. They weren't happy at having to buy a new one (£400 at the time) after breaking the first one.

 

That's a good example of the sort of thing I mean by not skimping on your infrastructure. By using an unqualified installer you've ended up with a damaged cable you can't trust. What are the odds that the one working link you have is 100% OK ? About nil I'd say.

[AlanD]

...as long as the 40m copper run is not between buildings which might be on a different "phase" of electric....I'd be wanting 2x copper....In fact...EI think I'd be wanting that even if it was 10G...because its really difficult to fill a 1Gb line of data - unless you have some serious kit...like a server loaded with SSDs. And filling 2x1Gb/s lines would be harder...

 

But if its between buildings..or external and unshielded..then you are at risk of the switches at either or both ends failing....and probably breaking electrical regs too.

[calwyn]

That's a good example of the sort of thing I mean by not skimping on your infrastructure. By using an unqualified installer you've ended up with a damaged cable you can't trust. What are the odds that the one working link you have is 100% OK ? About nil I'd say.

 

I don't disagree at all, but as we all know, schools will always take the cheapest possible option in almost every situation.

[mavhc]

That's why schools have no money, a rich man will buy expensive shoes that last a lifetime, a poor man will buy 100 pairs of cheap shoes that last 6 months.

 

Again, ask them for evidence, doesn't matter at all if the link isn't reaching capacity, ask for usage graphs over a week.

[dcwhitworth]

I don't disagree at all, but as we all know, schools will always take the cheapest possible option in almost every situation.

 

Absolutely. You need to pick the battles most worth fighting.

[mavhc]

You need to get your objections/recommendations down on paper, and then point to them the next time, the official version of I Told You So

[MkII]

It's common to terminate fewer fibre ends. Companies don't usually unless you ask. As the hire of the termination kit is quite expensive though it makes sense to do a few if not all while you have it.

 

1gb fibre has two cables, transmit and send. So it's 1gb up and 1gb down. 1gb fibre run = 2 x copper 1gb runs.

[Katy]

 

1gb fibre has two cables, transmit and send. So it's 1gb up and 1gb down. 1gb fibre run = 2 x copper 1gb runs.

 

But copper has 8 wires, some Rx some Tx. So full duplex 1gb copper is 1gb up and 1gb down. So 2 x full duplex 1gb copper is more than the 1gb fibre run surely?

[dcwhitworth]

1gb fibre has two cables, transmit and send. So it's 1gb up and 1gb down. 1gb fibre run = 2 x copper 1gb runs.

 

Eh ? So you're saying fibre is full duplex whereas copper can only do half-duplex ? That's not true.

[TechMonkey]

Just to slightly necro, I learned today that between buildings you should have fibre, not copper, to prevent a "ground float".

Any difference in ground potential between buildings causes current flow on the ground plane, which is highly undesirable. Never choose to run copper low-voltage comms between buildings, and especially not today when fiber is cheaper than ever. Half the time when you see copper used it was not because of cost, but more because of an unfamiliarity with fiber

Also if one building gets struck by lightning then there is the chance your network cable will transfer the load to the other building, causing expensive damage on the way through.

 

Off-Topic, I also learned there is gel filled cable, for installations underground in harsh climates. Do not install this vertically or in the summer it heats up and the gel ends up in your termination point.

[dcwhitworth]

Just to slightly necro, I learned today that between buildings you should have fibre, not copper, to prevent a "ground float".

 

Also if one building gets struck by lightning then there is the chance your network cable will transfer the load to the other building, causing expensive damage on the way through.

 

Off-Topic, I also learned there is gel filled cable, for installations underground in harsh climates. Do not install this vertically or in the summer it heats up and the gel ends up in your termination point.

 

Yep, that's exactly why you don't want to link buildings by copper. The lightning issue is a potential biggie too, although if your buildings are reasonably close together it probably won't be a problem as it will hit the buildings for preference which should be adequately grounded. However back in the 90s I used to work on an airport site which had several buildings linked by copper. We had several instances of lightning ground strike which would penetrate the ground and follow the path of least resistance (the copper cable) and blow kit up in the comms rooms.

Edited August 6, 2018 by dcwhitworth

[AlanD]

...its not just lightening...neighbouring houses in a street at fed by alternative phases....and usually different buildings within a site are on different electrical phases. Sometimes, the stage in a hall might have its stage lights fed by all three phases. This can produce a potential of 300V or so between buildings ...and while switches can normally tolerate this there is a risk of electrical shock...and while the path through ground is normally highly resistive I wouldn't like to put it to the test.

 

So, copper between buildings is an absolute No No for safetly.

[PotNoodleTech]

Our school has recently been subjected to a couple of IT Audits, one of which was particularly obsessed with infastructure & would like to offer to rewire the whole school.

 

"Hi I am here to give you an independent professional audit to check you're wiring. OH MY GOD LOOK AT ALL THIS WIRING!! You need to have it all replaced!! I can do it for you.....for......say £50,000????"

[mthomas08]

We always install fibre when we can. It's more 'future proofing' which I am a fan of. You may think you won't ever use 10GB..... but 15 years ago I wasn't too sure we would be so dependent on 1GB in a school...

 

If the capacity, time and money is available for 2x fibres.. do it. If you have a choice of 2x coppper or 1x fibre, then why not go 2x copper. Can I choose both?

 

Would you one day upgrade your current kit to suit a fibre. The question isn't so simple until you look at the bigger picture and I don't think there is a right or wrong option.