Channel (WAS: RE: [MLB-WIRELESS] [TIB] A new offer has been added to TIB-23/01/2003)

[Simon Butcher]

<snip>
> We're aiming for a huge network of interconnected nodes. 
> Meaning, for example
> 
> 	a <-----> b <-----> c
> 
> node a and b can talk via IBSS, and b and c can talk via BSS, 
> laser, carrier pidgeon, smoke signals, whatever, and a and c 
> can talk to eachother as node b is routing.

Being "Melbourne _Wireless_", RFC1149/RFC2549 could be useful after all!

April fools jokes from the past aside, since IP routing plays such a
vital role in mesh networking on a scale MW is attempting to achieve,
there's nothing saying that it must be IBSS, BSS, or 802.11-anything for
that matter.

> One problem that will hopefully resolve as the network is 
> developed is that with this method, you can't open your 
> laptop on the other side of town and just expect a 
> connection. You need to know what nodes are nearby, and what 
> channel/protocol/SSID they're running etc.
>
> I think it was Simon Butcher that proposed on the list a 
> month or two back that maybe we can standadise a "public 
> access channel". ie. once nodes are interconnected with 
> whatever method they want, they offer an omni on channel 1 
> with the same SSID as everyone else to standadise how people 
> can connect.

Big mistake on my part. I received many abusive flames to keep me quiet
on that subject. It appears that for connecting, you should be able to
get away with just the SSID remaining 'wireless.org.au' and a card's
driver looking for that SSID. Oh, and maybe an antenna in the fringe
area of a hot-spot.

As far as 'seamless roaming' goes, it appears by the flames I got that
my idea of using RFC3344 ('Mobile IP') would never work (along with the
obligatory four letter words about regarding my intellect).

With limited hardware on loan for a weekend recently, I did some
brutally cheap testing of my theory. I found that two access points on
the one channel, with overlapping boundaries, and a good backbone
between the two AP's (ESS), works well. Mobile IP, IMHO, certainly seems
viable. If anyone can tell me why it's not viable other than "you're an
idiot", please do, I could have easily missed something since I don't
have the hardware to do proper analysis.

While roamers using Mobile IP outside of their home network would
generate extra traffic on the mesh, IMHO they wouldn't normally be
capable of being able to run at speeds high enough to cause too much
trouble. Plus the mesh would need some sort of QoS to work around
bottlenecks, right? Well, that and the tunnelling/small-world thing
several of us have our eyes on..

Regardless of roaming, a uniform channel and SSID should be available
for people curious about the network, or don't really need anything as
extensive as a p2p link.. I seem to remember mentioning a few times
something about doing weak channel management ;)

Which reminds me, looking at the SSID's around the place, has anyone
read http://melbourne.wireless.org.au/wiki/?RFC (section 7) before
setting up p2mp links? Or is this document so horribly out of date
(November 21, 2002) that something else was devised?

<snip>
> > Can someone please correct me if I've missed something. 
> Putting a $125
> > AP up a pole is cheaper and more convenient than $60 WNIC +
> > $88 PCMCIA
> > cradle + $40 486PC in the roof.
> 
> True. I'd go for this option wherever possible. Maybe use an 
> AP that is capable of bridging to another AP to connect to a 
> nearby node, and run an AP in BSS mode for public access.

I'm personally waiting for 802.11g-draft gear. OFDM should prove itself
worthy of a place on everyone's long distance links. The D-Link AP
coming out seems much better than a few of the other brands I've looked
at (despite people incorrectly comparing its 54Mbps RX sensitivity to
802.11b cards' 11Mbps RX sensitivity and moaning).

Thanks to Julian Featherston's convincing arguments over e-mail, I'm
probably going to use an AP per p2p link from my node too.

Cheers

 - Simon


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