[115361] in North American Network Operators' Group
RE: Wireless bridge
daemon@ATHENA.MIT.EDU (Tim Huffman)
Thu Jun 18 11:17:44 2009
From: Tim Huffman <Tim@bobbroadband.com>
To: "nanog@nanog.org" <nanog@nanog.org>
Date: Thu, 18 Jun 2009 10:16:53 -0500
In-Reply-To: <005c01c9f015$852ae490$8f80adb0$@com>
Errors-To: nanog-bounces+nanog.discuss=bloom-picayune.mit.edu@nanog.org
We're a WISP, so I have lots of experience with this kind of thing. The pro=
blem with using 2.4GHz equipment is that there's a whole lot of noise out t=
here (run Network Stumbler sometime on a laptop with a wireless card, and y=
ou'll be shocked by just how many wi-fi APs are floating around).
You didn't mention your bandwidth requirements, but I'm assuming that you'r=
e trying to get more (and spend less), so I'll only recommend unlicensed ge=
ar. For that distance, you might want to consider using a 5.2GHz radio. The=
FCC limits their transmit power, so they only work well in short-range app=
lications (>2 miles or so), and 5.2GHz doesn't propagate the way that 2.4GH=
z does, so there tends to be much less noise in that band.
The Motorola PTP400 series (http://www.motorola.com/Business/US-EN/Business=
+Product+and+Services/Wireless+Broadband+Networks/Point-to-Point+Bridges) i=
s very good (Asymetric Dynamic Frequency selection means that each side can=
pick the best frequency to transmit on, and ARQ means that scrambled packe=
ts get handled at the wireless layer), and throughput tops out about 45Mbps=
(300Mbps for the PTP600 series), but they are expensive. They can be purch=
ased in many different bands.
On the lower end, we've been using Ligowave (http://www.ligowave.com), and =
had good results from them, for the price. They also come in many bands, an=
d run about $3000 (for the model with an integrated panel antenna), support=
throughput up to 45Mbps, and also support ARQ.
Hope this helps.
Tim Huffman
Director of Engineering
Business Only Broadband, LLC
O (630) 590-6012
C=A0(630) 340-1925
tim@bobbroadband.com
www.bobbroadband.com
> -----Original Message-----
> From: Peter Boone [mailto:NANOG@Aquillar.com]
> Sent: Thursday, June 18, 2009 8:06 AM
> To: nanog@nanog.org
> Subject: Wireless bridge
>=20
> Hi NANOG,
>=20
> 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.
>=20
> 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 connec=
t
> 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).
>=20
> 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.
>=20
> 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.
>=20
> 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 acces=
s
> 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 clea=
n
> 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.)
>=20
> 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 confiden=
t
> it will be effective.
>=20
> 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 :)
>=20
> Peter
>=20
