Re: Roaming in ESS network

[Dan Williams <dcbw redhat com>]

On Thu, 2010-02-25 at 09:55 +0800, 代尔欣 wrote:
> Hi all,
>      Have an question about roaming in ess network, NetworkManager
> support this capability or not? From the NM codes, after established
> the wifi connection, the NM semms in idle state and just listening
> some signals. So seems NM itself can't do this. Then which  module
> handle the roaming action? driver? wpa_supplicant? Hardware? My
> understanding is driver, if it is, those drivers in linux distrubition
> support or not? or need open some compile options? 

Roaming between access points within an ESS is completely controlled by
the driver and wpa_supplicant.  FullMAC drivers usually do the roaming
automatically in firmware, while mac80211 drivers will often let the
supplicant handle this.  The supplicant handles this by detecting that
connection to the current AP has dropped and automatically reassociating
with a better AP within the current ESS.

NM itself doesn't care about roaming, *unless* you specify a BSSID to
lock the connection to via the connection editor.

Dan