[clug] Wireless network over belconnen

Andrew Smith andrew at coolchilli.com
Thu Jun 17 12:25:18 GMT 2004

Hi Alistair, this is my reply from a couple of months ago, sorry :)

You're quite correct about the mesh networks, it's difficult and can also
present problems with latency, having bandwidth etc from repeated hops.
Height is the only way to go, we need people who live on hills, and are
happy to run a sector antenna with a back haul elsewhere.  (I have installed
and manage a few decent sized Microwave MANs in and around
Tuggeranong/Woden/Weston Creek and have in-principle agreement from some of
my customers to back-haul public/community wireless traffic).  Obviously
this is only worthwhile if there were enough interest.  In the next few days
I will be testing a NLOS link from Weston Creek to Belconnen, if this works,
and there's enough interest, it could become quite a good, functional

One of the stumbling blocks I've found in talking to people is this can be
perceived as a solution looking for a problem, ie: what's the point of doing
it?  What can I do with it?  The main 2 motivations I've seen are sharing
Internet access, and for the hobby/nerdy/cause I can aspect.  I run an open
AP in Weston Creek which has access to use my <insert ISP> flat rate link.
(Of course if that usage grows too high I wouldn't feel comfortable doing
that and would turn it off/restrict it).  One thought I did have though, was
to provide access to my rsync server and network infrastructure (DDNS,
Apache, Public FTP).  It's nice to be able to do updates to my Linux systems
from a local file repository at decent bandwidth, it would be great to use a
server elsewhere in town for distro X which wouldn't normally have stuff
for.  The need for a carrier license is only if someone were to make a
profit from the activity, so sharing seems to be ok.  Of course with a
benevolent sponsor (Brian, I'm thinking of you here :) providing free data,
that would be solved.  Easy!

In terms of equipment, I work with mostly proprietary gear but have been
playing with various 802.11 devices (mainly standalone APs, D-Link 900s) and
am happy to buy-in a bulk order at dealer price to minimise cost for those
who are interested.

Anyone who's even thinking about this should register themselves here

Hopefully this discussion isn't going to be deemed too off-topic, there
would be quite a common interest amongst the Linux community, for anything
to progress it certainly needs a good core group to build from.


----- Original Message ----- 
From: "Alastair" <linux at d-silva.org>
To: "Rohan Mitchell" <rohan.mitchell at undefined.homelinux.net>
Cc: <linux at lists.samba.org>
Sent: Thursday, June 17, 2004 8:08 PM
Subject: Re: [clug] Wireless network over belconnen

> On Wed, 2004-06-16 at 15:15, Rohan Mitchell wrote:
> > Hi all,
> > Some friends and myself are planning on setting up a wireless mesh
> > network across belconnen, using 802.11b/g cards with debian, high gain
> > omnidirectional antennas
> I've been trying for the last year to esablish a network around
> Tuggeranong. Theres a rudimentary and somewhat unmaintained website at
> http://canberra.freenet.in-a.us
> These are my findings . . .
> 1. Lots of people will say they are interested, but not many will
> actually follow through with it.
> 2. Canberra is unsuited to mesh topologies - theres too much distance
> between nodes to use omnidirectional antennas.
> 3. Stay away from Colinear antennas - they're a pain to make, perform
> poorly and are extremely fragile. If you have the time, make a slotted
> waveguide, or if time/money is short, a discone. You can make up a
> discone in about half an hour and it will perform way better than the
> colinear.
> 4. Carrier licenses are hideously effective (around $10k if I remember
> correctly), but what you run over a private VPN is your business :)
> 5. You don't want any old hardware - most cards I've seen require a PCI
> 2.1 slot. Pentium 2 or more recent is fine, but I haven't yet come
> across a Pentium with a suitable PCI slot (not that I've been looking
> particularly hard). I do have a pile of Celeron systems available for
> this exact purpose, but they did cost $$, so I'm obliged to ask for $$
> in return.
> 6. We should co-ordinate IP ranges so that the networks can be linked at
> some point.
> My (new) setups are thus:
> If theres power available in the roof space:
> FreeBSD gateway with 2 DLink DWL-G520 cards (Atheros based, 108mbps
> proprietary mode)
> OSPF for routing (Zebra)
> a couple of NICs
> If theres no power available in the roof, replace the cards with APs or
> maybe USB adapters if you can get drivers. You really want to minimize
> the distance that you have to run RF, as the cable is lossy and
> expensive (whereas CAT5 and USB cables are cheap). If you want to run
> power over your cat5 cable (as opposed to power over ethernet, which is
> 48V), I've designed a small switchmode power supply to step down
> anything up to 40V to 5V (check if you really need it first though - the
> DWL-1000ap and DWL-900+ap that I've got will accept quite a high input).
> I feed +12V from the computer's power supply via cables soldered to the
> NIC.
> One wireless interface runs as a client on a directional antenna (Golden
> Circle is your friend), while the other runs as an access point on the
> omnidirectional antenna.
> Thats about all I can think of for now - I'm sure I'll come up with more
> later.
> -- 
> Alastair D'Silva mob: 0423 762 819
> Networking Consultant fax: 0433 141 032
> New Millennium Networking web: http://www.newmillennium.net.au

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