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We have two buildings that are across the street from each other. Each has their own separate network. We needed to connect them together using a fast connection because of the large number of files that are copied between the networks on a daily basis. We have a wireless bridge setup right now between the buildings that gives us about 20Mbps (it's two Aironet 1240AG in root/non-root configuration).

Unfortunately there's a lot of RF interference in the area (lots of residential buildings) and the Aironet's lose connectivity on a daily basis (which leads to a lot of disgruntled users). I'm thinking about upgrading to some Motorola PTP wireless bridges but I wanted to ask, am I going about this the right way? We went with the wireless bridges because it was cheaper than getting a hard line between the two buildings but I'm starting to regret that idea given how badly these AP's are working. Any suggestions?

Edit: The Aironet's are using the 5Ghz band and use 802.11a. The antennas are directional panel antennas.

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Are you currently using good quality directional antennas? If not, I'd try that first. The more narrow the beam, the better, as you can literally put one person on each antenna and move until the signal peaks. – Michael Graff Dec 3 '09 at 1:15
Are the 1240AG running on a 5GHz or 2.4GHz channel? If they are running on 2.4, do you get less interference on a 5GHz channel? – ctuffli Dec 3 '09 at 16:59
We're using direction panel antennas and the Aironets are using the 5Ghz band. We're actually getting interferance on the 5Ghz band now where as a few months ago we weren't. I'm guessing it's a 802.11n router somewhere in the building interfering with our equipment but I don't have the equipment to prove it. – zippy Dec 3 '09 at 17:21
up vote 12 down vote accepted

Every "fixed wireless" installation I've seen with has always ended up being a pain (too slow, susceptible to intereference and therefore unreliable, prone to failures of gear, lightning strikes, etc). Assuming you're going to remain in these buildings for a long enough period of time to amortize the cost, get some fiber run. You won't regret it. Once fiber is in the ground / air and terminated, barring any physical damage (backhoe-induced-fiber-failure, gunshot, etc) it'll work virtually forever.

If you're lucky, you're under 500 meters or so, and can use multimode fiber and multimode transceivers / GBICs. Multimode fiber and the termination electronics are significantly cheaper than single-mode.

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+1, fiber, fiber, fiber. – Le Comte du Merde-fou Dec 3 '09 at 10:15
unrealistic answer. far too expensive for this guy. running that wire across underground would cost $1000 + . this answer doesnt deserve upvotes. – djangofan Dec 3 '09 at 17:00
Unrealistic? He didn't ask for the cheapest. Fiber is the fastest and most reliable way of doing it. – MikeyB Dec 3 '09 at 17:09
@djangofan: My experience has been that fiber ends up being the cheapest answer if you need high speed, reliable, and long-term connectivity between buildings. High-end wireless gear isn't inexpensive at all, and installation typically requires mounting antennas and running cable. After your radios take a lightning strike or two, or after users become disgruntled / lose productivity because the connection is dodgy, you begin to see that the "expense" of fiber up-front pays off in the long term. – Evan Anderson Dec 3 '09 at 19:11
@djangofan: he is already running Aironets - those baby's aint cheap my supplier shows them @ ~$480/ea ... so he has ALREADY spent ~$1000. – Zypher Dec 3 '09 at 23:19

If you've got line of sight, there's some neat laser and directed microwave gear available. It ain't cheap, but it's fast and pretty reliable. Your best bet, though, from a speed and reliability standpoint is always going to be physical copper or glass, but you need to make the cost/benefit call yourself after researching the options for your particular circumstances and weighing them up.

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These may not be cheaper than a fiber run; but you can get gigabit throughput with these. We put up a 800 meter link with them and they've been solid.

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Those look pretty interesting. – 3dinfluence Dec 3 '09 at 2:47

try lightpointe

In this website... I primarily meant the laser beam products... however, I do see that recently they have introduced products similar to Bridgewave...

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I strongly agree with the fiber suggestion; I'll only add that, if the distance between the two buildings is under 100 meters, you can use CAT-6 cable instead of fiber and still have gigabit throughput.

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+1 - Very reasonable, assuming you use an outdoor-rated cable installed to code and have lightning arrestors on the ends of the cable. – Evan Anderson Dec 4 '09 at 14:30

Not sure what Motorola equipment you were looking, but you might compare it to Cisco's outdoor Aironet bridges. These will be better suited to the task than the 1240AG's that you already have. See the 1300 Series and 1400 Series.

The 1400's are probably overkill for your situation but I have 4 set up to create a redundant link between two sites approximately a quarter mile away from each other. We have them inside their respective buildings and are actually shooting through several roof lines. I don't have any performance figures handy but the two sites might as well be on the same lan. Ping times are normally 2 ms.

As others have mentioned if you stick with wireless it needs to be directional.

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My suggestions:

  1. Switch to Wireless-N band (i recommend the $35 dlink DIR-615 router or a more expensive one if you need to swap for a bigger antenna)


  1. Use a DD-WRT repeater to extend the range (for n-band, use a cisco wrt300n for about $45)
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He mentioned that there is a lot of RFI in his area. As such, upgrading to N isn't necessarily going to help him. A good recommendation will need to be something that either 1) moves away from commodity RF gear to something in a licensed (or less used) spectrum or 2) otherwise limits the RF interference (think two very tight directional antennas). – EEAA Dec 3 '09 at 1:13
In defense of the commenter, RF interference takes many forms. I've seen environments with a ton of 2.4GHz interference but with little to no 5GHz interference. In these cases, switching to a 5GHz 802.11n solution might work. For a business environment, I wouldn't skimp on the gear. – ctuffli Dec 3 '09 at 16:57
an N network at 20% has 3 times the bandwidth of a G network at 20%. RFI doesn't mean that its impossible. changing wireless channel , etc., can solve that issue. no reason to give me minus votes for trying to help with a realistic answer. – djangofan Dec 3 '09 at 16:58
DD-WRT/tomato do not magically change consumer grade hardware into enterprise grade hardware. – Zypher Dec 3 '09 at 17:20
no, it does not. what it does is turn it into the easiest REPEATER device that there is. – djangofan Dec 3 '09 at 21:05

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