Question on 802.11r

Antonio Quartulli antonio
Tue Nov 12 01:19:49 PST 2013

On Tue, Nov 12, 2013 at 08:54:55AM +0000, michael-dev wrote:
> Hi,
> Am 12.11.2013 05:36, schrieb Ben Greear:
> > Now, I have a somewhat related question:  Should the station
> > re-acquire DHCP lease after successfully roaming? ...
> > So, it would be nice to skip
> > DHCP, but I'm not sure if that is how real-world networks
> > are configured?
> even without 802.11r when devices are roaming within the same SSID, some 
> don't refresh DHCP after changing the BSSID. I believe a recent version 
> of MAC OS was doing so and maybe others, though I'm not sure which HW/SW 
> exactly was used on client side. So that is why I built DHCP-Snooping / 
> IP+ARP-Filter on my APs in a way that those stations don't loose network 
> connectivity.


I would like to inject a suggestion here: another "easier" approach could be
to use a sort of middleware on the APs which would take care of handling these
kind of events (i.e. roaming) with low packet loss and little connection

What I refer to is called batman-adv[1] and it is a (wireless) mesh routing
protocol implemented as an in-tree kernel module.

Even if in your case you do not have a mesh network, batman-adv could still help
to create the abstraction of a unique big ESSID and will take care of routing
packets to the correct AP (this is the part that is going to help with the
roaming). Just to clarify: it works below the IP layer so for the user (the
client connected to the AP) it will look like being connected to a normal ESSID,
so the impact is rather small.

I think it is worth giving it a try.

Best Regards,


Antonio Quartulli
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