[MLB-WIRELESS] Question to list

Miki Shapiro aris at pharoe.com
Wed Aug 24 11:22:35 EST 2005


Thanks for the answer Dan

I'll start by putting an antenna on my home AP, hooking it up and seeing 
what I can pick up. I may put another directional antenna to 
point somewhere meaningful to link up with other nodes (possibly GHO).

Again, thanks for the in-depth answer :-)

Mik

On Fri, 19 Aug 2005, Dan wrote:

>> From: owner-melbwireless at wireless.org.au [mailto:owner-
>> melbwireless at wireless.org.au] On Behalf Of Miki Shapiro
>> One use I have in mind is hook up my CarPC (which will also get an
>> antenna) to my home server (VPN) when within reception limits via nodes in
>> the area it is in.
>> First question is of course can this be done via nodes in close proximity
>> to the car?
>
> Yes it could if the nodes in question offer a DHCP service.  Some nodes do,
> a lot of nodes don't.  It's up to the node-owner as to what services they
> offer.  The network is a collection of individuals more than it is an
> organisation, and node setups are mostly not standardised.
>
>> Second question - is there some high-alt node (Dandenong Mtn?) with a
>> wide-enough directional cone that I can use when within areas of eastern
>> melbourne?
>
> There is - Node GHO on Mt Dandenong has three wireless radios on it -
> however the signal strength from any of these radios require you to have a
> high-gain directional antenna like a dish, mounted on a high enough mast or
> building to get a good line-of-sight.  Your car would need to have a tall
> pole sticking out of it with a big, auto-tracking dish on it.
>
>> Third question -  do the nodes know how to route between each other or
>> do they only have routing configured to their
>> adjacent nodes (and other manually predefined routes)?
>> Is any dynamic routing or meshing implementation being used? That's a
>> leading question to "will my car be able to access home by hopping" 4
>> nodes?
>
> Yes - nodes in Melbourne Wireless use OSPF.  There's a bit written about how
> we use it, and some maps of the network in the Melbourne Wireless site.
>
>> Final question - anyone have any experience with non-stationary WiFi
>> communicating with stationary nodes?
>
> Personally, not much.  In a conventionally routed network like Melbourne
> Wireless, mobile nodes can't really "roam" between nodes because their IP
> address would have to change from one AP to the next.  Also, Melbourne
> Wireless uses different SSIDs on it's APs and 802.11b roaming requires that
> the APs have the same SSID.
>
> I have recently taken an interest in Mesh networking and in particular the
> OLSR protocol which is being used in a lot of wireless networks around the
> world.  Mesh networks do allow roaming over a wide area.  In fact, some
> people have gotten mesh networks to work between cars moving at highway
> speeds.  I've haven't gotten much further than the thinking about it stage
> though.  OLSR and mesh networks in general suffer from non-scalability - but
> anecdotal evidence shows that mesh networks of up to 50 nodes are possible
> using Linksys WRT54G routers.  If the mesh got any bigger than that you'd
> want to think about splitting the mesh into separate meshes and doing more
> conventional routing between them.  The most attractive feature of Mesh
> networking is the simplicity of configuration.  In Germany some guys have
> written a firmware for the Linksys WRT54G and WAP54G called "Freifunk
> Firmware" which makes configuring a node amazingly simple (and cheap).  I'm
> keeping my eye on the OLSR mailing lists and may experiment with OLSR myself
> in the future.
>
> Cheers,
>
> Dan
>
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