Wireless bridge

Peter Boone NANOG at Aquillar.com
Thu Jun 18 08:05:56 CDT 2009


Hi NANOG,

I'm looking for some equipment recommendations for a wireless bridge between
two locations approximately 500-800 meters apart. The current setup for this
company has been extremely unstable and slow. I don't have a lot of
experience in this area so I was hoping someone could give me a few
pointers.

Currently, both locations are using Linksys WRT54GL's flashed with DD-WRT
firmware (Yes, 802.11g. All extra bells and whistles are disabled in the
firmware. They were set up for WDS so other wireless clients could connect
to the same access point, with varying degrees of success. Not very
important). They are connected to SmartAnt 2300-2500 MHz 14 dBi directional
antenna mounted on the roof (extended pretty high for perfect line of
sight). I'm not sure when they got these antenna exactly but I'm told it was
when WiFi was very new. The network is very small so both locations share
the same subnet (192.168.1.0/24).

They have gone through numerous Linksys access points over the years. The
wireless settings are tweaked as best as possible, and we have found the
connection to be most stable when the TX is limited to 6-9 Mbps.

We have explored other options as well. An internet connection at each
location + VPN is out due to very slow upstream speeds (the buildings are in
an industrial area, ADSL is the only option.) The max they offer on regular
business accounts is 800 kbps up. T1 lines are even slower and even more
expensive. They won't offer us any other solutions such as fibre. We have
considered running fibre/coax but there is too much construction activity
and other property in the way.

I'm looking into RouterBOARD right now, considering a RB433AH and R52H
wireless card, but I'm not sure this will actually solve the problem. It's
difficult to determine if the issue is with the antennas or access points
(for example, after a good thunderstorm, the wireless link will be down for
at least 12 hours, but will fix itself eventually. Resetting either access
point will keep the link down for at least 30 minutes. Using an airgun on
the access points tends to make them more reliable, even if they are clean
and dust free. From the admin interface, each access point will report
seeing a very good and strong signal from the other, yet they refuse to
communicate until they feel like it a few hours later.)

Any suggestions welcome. I'm sure you can tell cost is a bit of a factor
here but it will be easy for me to justify a higher price if I'm confident
it will be effective.

While I'm at it, I've been reading along on the list for over a year now;
thanks everyone for sharing your real world experiences :)

Peter





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