Log In

Come Join Us!

Are you a
Computer / IT professional?
Join Tek-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Tek-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here


Fiber Question

Fiber Question

Fiber Question

I am getting prepared to create a campus wide network and I have a small obstacle in my path... a lake it is approximately 1km across.

Can I use direct burial fiber and just lay it on the lake bed or do I need something special?

Anyone have any insights?


Allan D. Reed

RE: Fiber Question

I would not do it that way. Definitely conduit of some form or another. Get a company that does outside plant work to at the least plow it in some innerduct and avoid the lake all together if possible. It may cost more $$ but it is a better solution.   

RE: Fiber Question

Your best be is to around, or under.
Never lay it on the lake bed, s it will surely be snagged and damaged at some point. Also, there is the problem of buoyancy, even in conduit. It will float up and get damaged. By the time you spend the money to get the cable properly anchored in the water, you could have gone around or possibly under. That may be a long pull for a directional drill to go under, but likely less costly than all the other options in the long run.

RE: Fiber Question

How does the telco have their facilities run in that area?


RE: Fiber Question

Of course the cables go across the big ponds, oceans, using specialized cables en.wikipedia.org/wiki/Submarine_communications_cable all the time. These cables carry something like 95% of intercontinental communications.

While it may be practical to use something like this www.hyperline.com/catalog/cable/fo-ad-out.shtml to go across your lake it might be a better idea to go around or use a RF link. A lot depends on the nature of the lake.

If the lake is ornamental and has no active use with boats, people and the like then that is a plus. The depth of the lake is an issue. In many ways the deeper the better and the faster it gets deep is a plus. The notion is to keep the cable out of harm's way. The other problem is how to transition the the cable from land to water. Again this depends on topography.

If you decide to go across the lake be sure to leave sufficient slack in the cable so it can settle without getting to tight. Also be sure you have a plan for replacement in case of damage. Don't make it excessively difficult to replace the cable by threading it through a bunch of intermediate ducts. My notion would be some sort of enclosure on each side of the lake that could contain at least 5M of across the lake cable in a way it could move out of the enclosure easily. These enclosures might not have splices/connectors initially but would be where a replacement cross lake segment would terminate if required.

In short I wouldn't rule out going across the lake. Post additional details if you want. A Google Earth link would be nice...

Good luck!

RE: Fiber Question

Thanks for all the replies.  Going around is a bit difficult, namely becuase an interstate runs across this lake.  I have attached a link to google earth so you can get a better idea of what this looks like.  On the map, I am going from point A to point B

Google Maps

I am trying to get a depth chart for that area of the lake, but have been unsuccessful thus far.  That part of the lake, east of the interstate, sees relatively little traffic and most of that is paddle boats or canoes.  The reason being is that the interstate is too low to allow for significant boat traffic.

You guys wouldn't know what the ball park price per foot submarine fiber would be, would you?

Thanks again!


Allan D. Reed

RE: Fiber Question

I agree, going around isn't much of an option...

It looks like Lake Norman is owned by Duke Energy. You will need their permission for a submarine crossing. Might not be a problem. Could be good PR for them with little impact on their business. It does sound like the traffic is suitable for a crossing.

A USGS topo map will likely give you an idea of the bottom contour. From the looks of the surrounding area I'd guess it's less that 50' deep. As long as significant debris isn't swept in during flooding you could be OK with snagging.

Cable cost, I'd give Hyperline a call. You also might want to call www.marencoengineering.com to get some ideas.

Other options:

** VPN - set up a VPN tunnel over either an existing Internet connection or a dedicated one.

** RF - WiFi or licensed data link. Could be as DIY or professional as you want. As short a link as it appears to be  I'd pop up a pair of WRT54GL units with some 16dBi flat panels and see if that was reliable enough. Check with www.fab-corp.com, they should be able to give you more info.

** Leased line - Many areas now have MetroE service. This is much cheaper than traditional services. Check www.telcosolutions.net/products/metro-ethernet-mpls-vpn to get an idea. ISPs and telecoms in your area can provide quotes.

It boils down to the same old questions of cost, reliability and speed. If you went submarine who would actually be doing the work?

RE: Fiber Question

Yeah...nothing like a lake and an interstate to mess with a network layout.

I knew about the submarine cables, but wasn't sure if it applied to me as my google searches turned up companies who ran cables along the sea bed for 1000s of miles.  My 1.5km is a drop in the bucket for them...

The 1.5km distance ruled out wi-fi, but I am looking at RF, but I think the bandwidth is going to be the limiting factor.  I need 1GB link between the buildings.

I also researched MetroE, but I still think the fiber will be cheaper.  I was on Hyperline getting some pricing and it is about $7 per meter, so 1.5Km would be about 10K in cable.  I don't know what install costs are, so triple that number to be safe and say $30K for everything.  At $1500 per month for 100MB metroE, that is a payback of only 20 months and I go much faster with GB or 10GB speeds.   


Allan D. Reed

RE: Fiber Question

1.5 kM across water certainly does not rule out WiFi. There are folks going 20 miles with it across water. Some island in Michigan as I remember. According to Engadget the unamplified record across land is 125 miles.

However 1 gB does rule out WiFi...

I'd still get RF quotes. Knowing your speed requirements you might want to give www.meridianmicrowave.com a call.

RE: Fiber Question

Thanks for the resources.  

I went on their site and they do have a 1.5Gbs solution that starts around $30K.  So on the surface, it looks like fiber vs RF is about a wash. With the RF solution there is the FCC licensing fees which are currently $3K per 10 years.  That's just under $30 per month, so it is negligible.  But, you know the government.  That could be $6000 ten years from now...



Allan D. Reed

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Tek-Tips Forums free from inappropriate posts.
The Tek-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Tek-Tips forums is a member-only feature.

Click Here to join Tek-Tips and talk with other members!

Close Box

Join Tek-Tips® Today!

Join your peers on the Internet's largest technical computer professional community.
It's easy to join and it's free.

Here's Why Members Love Tek-Tips Forums:

Register now while it's still free!

Already a member? Close this window and log in.

Join Us             Close