On Mar 31, 2012, at 3:38 AM, Shahab Vahabzadeh <sh.vahabza...@gmail.com> wrote:

> As I look for maps we need at least 3 or 4 outdoor radio, I think in these
> networks the best solution is to have only one SSID in whole network to
> give mobility for the network, is this called ad-hoc? or it has an other
> name?

No, it's still infrastructure mode, not ad-hoc.

Ad-hoc means "no access point".

All you need to do is set the APs up to use the same SSID and authentication 
methods, keys, etc.  It's pretty simple and can even be done with consumer gear 
(with less stable performance of course).  If you don't put the APs all on the 
same layer 3 LAN (same subnet), you'll need some sort of controller-based 
solutions so that a user's IP address still makes sense to their computer when 
they move from one AP to another.  If you can keep all the APs on one subnet, 
you won't need that.

It gets a bit more complex if you are using radio to link buildings together 
and/or backhaul to the access point.  There's plenty of good references on the 
internet.

Note that the wireless handoffs aren't perfect on basic 802.11 gear.  Your 
laptop might not pick the best AP if it can hear multiple APs.  And you might 
lose a few packets when you hand-off between APs, but it's typically no big 
deal.   Your ssh session would stay connected across those hand-offs just fine.

If you plan on doing VoIP on the wireless, it gets more complex yet - you have 
to worry about the time it takes handoffs and that can be more complex.  You 
have to implement WMM and DSCP.  You need to worry about low-speed users 
(1mbps, 2mbps, etc) on the same link.  It's a lot harder to build a VoIP 
wireless solution than a web browsing wireless solution, but still plentty 
possible to do without expensive equipment.

In summary: you probably should find a guide on how to build wireless networks, 
preferably a vendor agnostic one.  You will either be the hero of your 
organization or the enemy, depending on how well your network works.

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