Help with getting started with fiber

Simon Brazeau · ‎04-15-2011

Hello everyone. I’m about to start my first project with fiber and I need some help. I’ll try to explain the project quickly followed by my questions.

I’ve been contacted by someone doing automation in PLC at a mine. They want to be able to access their PLC systems through LAN. Currently they do not any type of network LAN underground. The mine shaft has 8 underground levels. First level begins at 540 meters right up to the last on at 1150 meters. The levels between all vary 35 meters to 180 meters apart from each other. At the moment only the levels 2, 5 and 8 (700 meters, 925 meters, 1150 meters) need to have access to a network.

First and most obvious question is can MMF 50/125 - 12 fiber cable be used? I plan on using Cisco Catalyst 3560 switches for the 3 underground levels. I will need one direct run from ground level to 8th and the rest will vary. Will I need to use SMF? Any suggestion on cable and sfp would be appreciated.

Second, we want to have fiber termination boxes on all 8 levels, having in each panel 6 pairs coming from the above level and 6 pairs going to the next lower level. My question is for the levels that will currently not require a networking, can the termination just be jumpered over using patch cable to continue the run? This will be done on the other 5 levels for now. Will this cause any loss or degradation of signal if done at the remaining 5 levels?

Thanks in advance for any help.

Leo Laohoo · ‎04-15-2011

First and most obvious question is can MMF 50/125

It might but I wouldn't bet on it. SMF is your best bet. I know that SMF fibre runs and optics are expensive but at that distance ...

Cisco SFP Optics For Gigabit Ethernet Applications

http://www.cisco.com/en/US/prod/collateral/modules/ps5455/ps6577/product_data_sheet0900aecd8033f885.html

12 fiber cable be used

Is this 12 "pairs" or 12 "core"? It's up to you how many you want. Due to the nature of your environment I'd put more than less. You don't know WHAT might happen. I'd run, for example, TWO XX core fibres if it's possible. Should one fail, the you have the second one working.

I plan on using Cisco Catalyst 3560 switches for the 3 underground levels.

See, here's the million dollar question: How "clean" is the switch going to go? I mean the amount of dusts, humidity, vibration, temperature, etc? How many ports do you need? Do you want 100BaseFx? 1Gb? 10Gb? One more thing: Toxic and/or Flammable gas (such as methane) issues?

Second, we want to have fiber termination boxes on all 8 levels, having in each panel 6 pairs coming from the above level and 6 pairs going to the next lower level. My question is for the levels that will currently not require a networking, can the termination just be jumpered over using patch cable to continue the run? This will be done on the other 5 levels for now. Will this cause any loss or degradation of signal if done at the remaining 5 levels?

I don't like "lollipop" links because of single-poiint-of-failure but I can't say the same when it's in a mine shaft and you've got a budget issue. I'd go for separate links all the way to the top.

Simon Brazeau · ‎04-18-2011

First off, thank you for taking the time to help me leolaohoo!

I was pretty sure I would have to look into smf instead, not a big deal. I was talking 12 fibers, 6 pairs. At this time we only need 2 pairs. I do understand trying to plan for future and "in case of", this is why we are having 4 extra pairs. Also with the smf I was now looking at the 1000BASE-LX/LH sfp.

I’m still waiting on a few answers for the needed speed on the network. There will not be many systems, VoIP phones down in the mine, so I’m pretty confident at this time that the catalyst 3560 10/100 with sfp of 1000 we will be alright.

As for the "lollipop" links I understand that every point you have a connector/splice there can be failure. Is doing this kind of linking a common thing? Like I mentioned before we are trying to think for the future, so we were going to install a fiber distribution box on every level of the shaft. Another solution would be the levels that we currently don’t need networking, we can just loop about 2 meters of fiber in the distribution box and not actually splice it till we are adding network on that level. Is there a special enclosure that can handle this or can I just use the same distribution box I was going to use? Any thoughts or ideas?

Just a side note on the connection, we are going to daisy chain the 4 switches using the mini-GBIC. 1 to 2, 2 to 3, 3 to 4, then 4 back to 1 for redundancy.

Tom Randstrom · ‎04-19-2011

"Like I mentioned before we are trying to think for the future, so we were going to install a fiber distribution box on every level of the shaft. Another solution would be the levels that we currently don’t need networking, we can just loop about 2 meters of fiber in the distribution box and not actually splice it till we are adding network on that level. Is there a special enclosure that can handle this or can I just use the same distribution box I was going to use? Any thoughts or ideas?"

Give the location, I would connectorize at each level at the same time. This would eliminate the need to bring in a contractor a second time do splicing. A fiber jumper should not add too much signal loss given the 10K SMF optics. I would recommend a fiber distribution box which is designed for dusty environments (good sealing).

Just a side note on the connection, we are going to daisy chain the 4 switches using the mini-GBIC. 1 to 2, 2 to 3, 3 to 4, then 4 back to 1 for redundancy.

That should provide some level of redundancy. However, I am assuming all the fibers will be running the same sheath, so if the fiber cable gets cut, all the devices downstream will be unreachable. If you have the capability to run two fiber cables in diverse routes, that would improve survivability.