managing multiple wireless SSIDs (summary discussion)

[Tobias Roth]

[shortened quote]

> I recently asked this list how I could automatically detect and
> initialize my wireless interface based on any available SSIDs.
> 
> I received three responses for the three different "solutions"
> listed below:
> 
> rcng patch for "autoconf at boot"
>    http://lists.freebsd.org/pipermail/freebsd-mobile/2003-November/002284.html

just to clear things up a bit:

<shameless selfpromotion> what profile.diff does is detect the network
at boot or resume, whether wireless or ethernet, and configures the whole
system (not just network, everything: proxy, nfs mounts/, firewall, ...)
according to where the laptop is located. it also seamlessly integrates into
rcng and is easily removed as well </shameless selfpromotion>

since i did not receive much feedback back in november when i sent the
patch to -current and -mobile, i will try again now that 5.2 is out and
everyone has some more time. this will be in three weeks or so, i first
have to make the patch acpi compliant.

> "wiconf" utility
>     http://www.csh.rit.edu/~psionic/projects/wiconf/
> 
> "wlandetect" daemon
>     http://jelmer.vernstok.nl/oss/wlandetect/
> 
> What I'm particularly interested in discussing is the IDEA
> behind the above three utilities: "wireless roaming"

as someone else already pointed out, "wireless roaming" is not something
simple. if you want real roaming as with mobile phones, you need a
connection handover, so protocols with connections (tcp) do not get torn
down when being handed over. thus you want "mobile ip", and that is, afaik,
not yet ready for prime time.
for more mobile ip infos, see here or check google:
  http://www.computer.org/internet/v2n1/perkins.htm

> 1.) Solutions that allow "realtime" roaming
> 2.) Solutions that trigger only when external events occur
> 
> I'd like to discuss these two categories with this list and
> get some feedback. Particularly, I'd like to get a feel for
> what other people think is the "correct" solution and why.

in short: 2) is much simpler and can be integrated into FreeBSD right
now while 1) requires something like mobile ip which in turn requires
infrastructure changes to the whole network environment.

> Solutions that allow "realtime" roaming
> ---------------------------------------
> As far as I can tell, "wlandetect" is the only "solution" that
> falls into this category. It runs as a daemon, actively polls
> the network for available SSIDs, and reconfigures the wireless
> interface on the fly.

but what do you get out of that? one thing is to roam between
different access points of the same wireless network, but when would
you want to switch between different networks? without seamless tcp
handover, this is not usable i think.

cheers, t.