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Right now I have two buildings across the street from one another that both have typical consumer aDSL connections (something like 12 Mbs down/1 Mbs up). When I need to access resources on the other network, I VPN into the other building and do my work. The problem is that when I'm transferring large files, it's a very slow connection. And sometimes I'm remotely working with both of those networks so simply walking between buildings with a hard drive is out of the question.

What are some best practices to solve this situation? I've considered running a fiber link between the buildings, but is that a viable option and what is there to consider when doing that (I imagine a permit from the city would be needed to dig up the street)? Wireless seems like the obvious choice, but is it reliable, and would I get a significant speed boost?


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up vote 19 down vote accepted

I have a Customer with two buildings across the street from each other in a similiar situation. When I started working with them in 2003 we put in a fixed wireless (802.11b using Cisco Aironet gear at the time) system. It worked well enough, but we had outages when an AP failed, and a loss of performance when the neighbors all started putting up wireless Ethernet and other crud into the 2.4Ghz ISM band (yes-- we were using highly directional Yagi antennas pointed directly at each other, too). The Customer "upgraded" the system to an set of Proxim 802.11g APs in 2005 and saw very little improvement in performance.

When the Customer started running VoIP over the link it became very clear that the link wasn't very reliable and had reasonably unpredictable latency. This traffic, combined with the increasing size of the corpus of files that we were backing-up over the "air" each night from a file server located in the "across the street" location pushed us to recommend fiber.

We had the local cable television monopoly (Time Warner) run the fiber. For the Customer, this meant that they didn't do anything at all with permits, digging, hiring contractors, etc. The cable monopoly got the fiber run, put Ethernet switches at both ends, and told us "plug your network in to this port" on each end. That gave us a 100Mb/sec, rock-solid reliable connection between the buildings.

For the Customer, there is a recurring month-to-month expense. Initially I was opposed to this, however the "pay off" for the Customer paying for the fiber installation themselves versus the recurring charge turned out to be roughly 3 years. The Customer's financial controller also liked the idea of a month-to-month expense, versus a capital expenditure. (You'd have to ask him why... this is Server Fault, not Obscure United States Federal Tax Code Fault...)

Every fixed wireless link I've had the occasion to work with (all of which were installed by other contractors except for the one I've described here) have been problematic in some way or another, as compared to fiber. Fiber, once it's in the ground / air and working, works forever (unless it gets BIFF'd or shot). You'll change the electronics on the ends from time-to-time, but that usually just means an increase in speed or features. The fiber itself remains the same.

I'd recommend strongly against running the fiber yourself. You can save a lot of time by getting together with a cabling contractor who has done this kind of work before. They'll know what permits to get, and have heavy equipment available (like directional boring machines). They can tell you, too, if your buildings are close enough together to get away with using the less expensive multi-mode fiber optic cable versus single-mode (which can cover a lot longer of a distance but is much more expensive, both for the fiber and the electronics on the end).

Check with your local monopoly cable television provider, too. They may be able to run it for you and, depending on how long your company wants to stay in those buildings, what the month-to-month cost is compared to the cost of installing the fiber with your own contractor, and how your finance people feel about an expense versus a capitalized asset, you might found out that the monopoly provider ends up being the route to go.

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I'd vote this up 5x if I could. If you're asking a question like this, you have no business running cable across property lines. When the local gas/water/power/steam/telecom utility digs up your wire where you didn't dot the i's and cross the t's, not only will they gleefully cut it, but they will also blame your company for any issues within 50 feet of the hole. – duffbeer703 Dec 20 '09 at 19:42
Thank you, this is exactly what I was looking for! – mrduclaw Dec 21 '09 at 13:03

I've personally made this device Build Wifi Hi-gain Antenna and have two buildings 2km's apart able to run 44Mbit/s Wifi Connection without any problems (802.11g)

The whole cost ended up being about $70 excluding time, but it worked and worked well for over 2 years till I needed more bandwidth and ran SC fibre between them.

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This looks decidedly delicious. Thank you! Is there anywhere I can just buy one of these though? I kind of want it to "just work" since this is for a corporate environment, and to be able to call someone's tech support when it doesn't. – mrduclaw Dec 20 '09 at 10:51
I have seen them and therefore know that they exist, but I don't know where to buy one. – Catherine MacInnes Dec 20 '09 at 11:07
Unidirectional WiFi = wonderful, if you have line of sight. – Mark Henderson Dec 20 '09 at 20:52

if you can - go fiber. this investment will scale nicely in next decade or two and provide much more capacity than you need today.

if - because of costs / work needed it's out of question then wifi should do a trick.

if you would like reasonable performance - i suggest you look some access points compatible with 802.11a. i'm using outdoor osbridge on some wireless bridge - works very well. some benchmarks [ you'll have to use google's translate from polish to english ] can be found here.

or - even better some mikrotik platform with two such cards at each end running in nstream. this should provide you usable full-duplex link at pessimistic speed of 50-60Mbit/s even with smallest size of packets.

setup should be very easy with two regular access-points, and slightly more challenging with mikrotik but you'll get more control over things and better performance.

if possible - avoid 802.11b/g - those will give you lower performance.

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This looks great! Thanks! Do you have any links for setting up a fiber link, as well? I've never played with fiber. – mrduclaw Dec 20 '09 at 13:48
@mrduclaw - no, not really. it depends a bit on the distance - but if it's your first time - i suggest you get external company to finish the work. you can dig a trench, or even put HDP pipe, but let the specialists handle attaching the fiber to the patchpanels on both ends. you will also need media converters or switches with SFP ports. all-in-all fiber will be more expensive for sure, but it pays back.. once set [ privded it's physicaly secure ] - it'll work fine for long time. – pQd Dec 20 '09 at 14:14
When I was looking at running fiber a km, I called some local fiber contractors who were familiar with the building and office park. In your case, maybe you could talk to the business class sales office at your telco, explain the situation, and see what they can do for you. You might be surprised, unless it's Verizon. Then you'd still be surprised, just in a bad way. – Matt Simmons Dec 20 '09 at 19:44

Evan's answer is the best one for 95% of scenarios, but an edge-case solution in an area with heavy RF interference would be to use laser networking products.

Companies like fSONA offer equipment that allows you to establish highly-reliable links up to a few miles away. These solutions work really well, but are really expensive... I think a previous employer set one of these up a few years ago to establish a network presence in a historic building quickly, because getting the permits/signoffs for cable runs was literally going to take many months, and connectivity had to be established in a small number of days.

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This looks like a pretty sweet solution and I'd love to play with it. This is for a relatively small business though, so cost will weight in heavily. – mrduclaw Dec 21 '09 at 13:05

If the buildings are literally opposite each other, you could run a cable between the two over a catenary wire. I imagine you will also need assorted permits to install one of those over a public street (I imagine there must be some kind of minimum clearance requirement), but it gives you another option.

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This is something I really hadn't thought about. The buildings are the tallest in town (it's a small town), and they're twins, so it seems reasonable that the city should allow us to do this without too much issue. Thanks! – mrduclaw Dec 21 '09 at 13:16

Note, if you use an electrical, rather than radio or optical, link (e.g. string a Cat5 cable), then you need to ensure you have electrical isolation in place on at least one end. And surge suppression on both.

Two buildings, even next to each other, are likely to have slightly different earth potentials, this can lead to the network wire carrying current you (and the electronics at either end) definitely don't want.

Surge supression covers things like the wire, or one building having a local surge (e.g. a lightning hit).

Generally for a "wired" connection between buildings, even close buildings, are optical to avoid all this complexity.

Finally, don't forget that you will need to consider a backup in case of a fault, especially as the business grows to depends on the link.

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Thank you, I have read about this concern and that's why I left off electrical links in my list ( I just assumed everyone was either optical or wireless because of this ). Do you have any suggestions as to how to about actually setting up this optical link, since I think that's how we'd probably like to proceed? I've never ran any fiber optic links before, especially across a city-street. – mrduclaw Dec 20 '09 at 11:26
NOr have I :-). The simplest is probably two ethernet routers with matching optical transivers and optical fibre (there are plenty of options, so they need to match). NB. you will need to find out what local permissions you need (planning, access, ...) to string the fibre and supporting cable. – Richard Dec 20 '09 at 18:33

Ask your local ISP about the fiber. They can do a dedicated fiber for you by themselves or at least help you with a laying (don't agree on the rent of course :).

It could be pretty cheap and can give you very good speeds. For example in the company I has been working previously, ISP techs made a 300m fiber between our offices in Berlin for about 200 Euros (~300$) onetime fee plus a price of the cable (don't remember but also not very expensive). It is even cheaper than 2 good wireless access points.

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That sounds like an amazing deal. The price estimates I've found for running it myself have been astronomical in comparison, I'll be calling my ISP when they open today. – mrduclaw Dec 21 '09 at 13:13
the main idea is to call directly a local ISP company for your district. if they have something already laying or can add one more fiber, why not? of course all other companies will set a high prices because they should usually do a laying from scratch, obtain a permissions from the building owners etc. while ISP could already have everything this. – disserman Dec 21 '09 at 13:28
about an astronomical prices - I remember as 10 years ago we worked with one newspaper in Ukraine (exUSSR) who had a very slow Internet in the offices and decided to purchase a dedicated fiber between the cities Lviv and Kyiv (about 470 km). well that was expensive! – disserman Dec 21 '09 at 13:34

In a very similar situation I used a pair of Bridgewave 60GHz radios. They cost us $15K installed (that was three years ago, so should be cheaper now) and provided a 1GigE bridge that worked with 100% availability over two years before I left that employer. Check out their website, find a reseller/installer, and you'll be very happy. The only requirement is line of sight.

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I like that it can provide a 1Gb link, I don't like that it's $15k. I'll keep them in mind for the future though, as the company grows. – mrduclaw Dec 21 '09 at 13:14
Keep in mind that it was a one-time expense. Break it down to the three year amortization schedule, and $400/month will not look like such a big deal. (Consider this a hint how to sell it to the beancounters.) – Max Alginin Dec 21 '09 at 21:24

We have several buildings around our town that are linked together with a mix of fiber and wireless. With the fiber, just a couple of media converters connected off your switch is all that is required really.

In regards to the wireless, I'm not suggesting this brand of product is best but we've tried several very expensive brands before settling on Ubiquiti networks products for our wiress needs. The nanostations are inexpensive and run beautifully. We're using some that are outdoor and have a range of around 5km all for the price that is comparable to an indoor consumer 802.11 router. They are all very well constructed too. Recommend that you have a look.

There are many others out there... wireless is the way to go between buildings if there is no preexisting copper or fiber cable and or no channel to lay it in. It's extremely expensive to cut concrete and lay fresh cable as you can well imagine.

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These products actually look pretty reasonably priced. Thank you for the link! – mrduclaw Dec 21 '09 at 13:11
Amazingly, we just had a backhaul installed about 30km away on a hill around 2000ft high. The nanostations are working at that distance, with clear line of sight. They are only in the 200 milliwatt power. 16db antennas, not even parabolic. I'm blown away by the performance. – Matt Dec 21 '09 at 21:05

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