Marvell regulatory domain info storage?
slamb at slamb.org
Fri Oct 6 18:37:51 EDT 2006
On Oct 6, 2006, at 3:21 PM, Peter Jones wrote:
> On Fri, 2006-10-06 at 00:56 -0700, Scott Lamb wrote:
>> 3) Khaled said this: "You don't reconfigure your network card
>> every time
>> you travel." This is because the laptop gets its regulatory domain
>> information from the Access Point via 802.11d. You can't legally
>> Access Points in different regulatory domains without adjustment.
>> Now, I
>> have absolutely no idea what this means for mesh networking...
> Huh? That doesn't quite follow. You can't know if it's legal to
> associate with an AP during scanning, or even know what channels
> allowed to scan, until you've selected your regulatory domain.
> When a scan is initiated, you already have a list of channels
> that's ok
> to talk on, and it's determined by a static table in the driver,
> by the geo code read from the firmware on the machine -- typically the
> firmware of the WiFi device itself.
> See, for example, wlan_scan_create_channel_list() in
> libertas/wlan_scan.c, or ipw_request_scan() (and its helper
> ipw_add_scan_channels() ) in ipw2200.c .
> It's certainly possible to hack things up to use a user-settable geo,
> but that is not what drivers currently do.
I think my wording is at fault here. I'm talking about the way a
modern general consumer laptop is supposed to work. I have not looked
at any of the code you're describing. What I heard (which seems
consistent with a quick sanity check against wikipedia's 802.11d
entry) is that the AP sends out the regulatory domain as part of the
beacon, so laptops can read this information before transmitting
Scott Lamb <http://www.slamb.org/>
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