Thank you very much for the detailed explanation. Will look into wpa_supplicant and mac80211 then.
BR. 2012/12/10 Dan Williams <[email protected]> > On Mon, 2012-12-10 at 14:25 -0200, Franco Miceli wrote: > > Hi, > > > > > > I am working on a project that aims to assess how wireless roaming > > works. > > > > > > I am currently working with nm 0.8 and am lost trying to find out > > where in the code the roaming happens. > > > > > > Could anyone point me at some direction as to where to start? > > As others have said, it can happen at different levels. NM actually > never makes a decision to roam, that's all left to wpa_supplicant and > the kernel. There are two basic cases: > > 1) "thick" firmware that contains much of the 802.11 stack will almost > always control roaming in the firmware; the firmware monitors current > channel conditions and scan results and determines when to jump to a new > access point, does so, then notifies wpa_supplicant of the change. An > example driver here is 'orinoco'. > > 2) "thin" firmware leaves most of the 802.11 functionality to the > kernel, where it's implemented in the 'mac80211' kernel module. Here, > the kernels' mac80211 stack just passes signal and channel information > up to wpa_supplicant, which may decided to roam based on that > information. Example drivers are ath5k, ath9k, iwlwifi, and more. > > BTW, NM 0.8 is pretty old, 0.9 has been out for a long time. But the > roaming procedures are not different between the two, it's still all > controlled by the kernel and wpa_supplicant. > > Dan > > -- Ing. Franco Miceli CITS - Plan Ceibal - Investigación & Desarrollo Av. Italia 6201 - Montevideo, Uruguay CP: 11500 Tel: (598 2) 601 5773 int.: 2227
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