Thank you Jouni and Johannes for your replies. They were very helpful. I was not aware that the 802.11n standard itself allows channel bonding only on particular channel pairs. That restriction is generally not made very clear (I think). I definitely do not intend to build a system that does not comply with the 802.11n standard, so I understand that I should not get support to do that :)<br>
<br>As for hostapd's "802.11n: scan for overlapping BSSes before starting 20/40MHz channel", I am aware that the restriction exists to reduce interference between overlapping APs and to avoid performance degradations. I just want to take the control from hostapd about when to proactively start/enable 20/40MHz operation.<br>
<br>Thanks again!<br>Lara<br><br><br><div style="border-collapse: collapse; font-family: arial,sans-serif; font-size: 13px;">Date: Mon, 21 Feb 2011 17:05:26 +0100</div><font face="arial, sans-serif"><span style="border-collapse: collapse;">From: Johannes Berg <</span></font><a href="mailto:johannes@sipsolutions.net" style="color: rgb(0, 101, 204); border-collapse: collapse; font-family: arial,sans-serif; font-size: 13px;" target="_blank">johannes@sipsolutions.net</a><font face="arial, sans-serif"><span style="border-collapse: collapse;">></span></font><br>
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Subject: Re: hostapd + channel bonding + 5GHz</span></font><br><font face="arial, sans-serif"><span style="border-collapse: collapse;">To: Jouni Malinen <</span></font><a href="mailto:j@w1.fi" style="color: rgb(0, 101, 204); border-collapse: collapse; font-family: arial,sans-serif; font-size: 13px;" target="_blank">j@w1.fi</a><font face="arial, sans-serif"><span style="border-collapse: collapse;">></span></font><br>
<font face="arial, sans-serif"><span style="border-collapse: collapse;">Cc: </span></font><a href="mailto:hostap@lists.shmoo.com" style="color: rgb(0, 101, 204); border-collapse: collapse; font-family: arial,sans-serif; font-size: 13px;" target="_blank">hostap@lists.shmoo.com</a><br>
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Message-ID: <</span></font><a href="mailto:1298304326.3707.14.camel@jlt3.sipsolutions.net" style="color: rgb(0, 101, 204); border-collapse: collapse; font-family: arial,sans-serif; font-size: 13px;" target="_blank">1298304326.3707.14.camel@jlt3.sipsolutions.net</a><font face="arial, sans-serif"><span style="border-collapse: collapse;">></span></font><br>
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<br><font face="arial, sans-serif"><span style="border-collapse: collapse;">On Mon, 2011-02-21 at 17:57 +0200, Jouni Malinen wrote:</span></font><div><br><font face="arial, sans-serif"><span style="border-collapse: collapse;">> On Thu, Feb 17, 2011 at 05:40:14PM -0800, Lara Deek wrote:</span></font><br>
<font face="arial, sans-serif"><span style="border-collapse: collapse;">> > The ht_capab parameter in hostapd.conf enables 40MHz operation</span></font><br><font face="arial, sans-serif"><span style="border-collapse: collapse;">> > ([HT40-][HT40+]). I understand hostapd enables channel bonding only if there</span></font><br>
<font face="arial, sans-serif"><span style="border-collapse: collapse;">
> > will be no channel/bandwidth overlap with neighboring APs (802.11n: scan for</span></font><br><font face="arial, sans-serif"><span style="border-collapse: collapse;">> > overlapping BSSes before starting 20/40MHz channel). Is there some way where</span></font><br>
<font face="arial, sans-serif"><span style="border-collapse: collapse;">> > I can control 40MHz vs. 20MHz operation myself without it being censored by</span></font><br>
<font face="arial, sans-serif"><span style="border-collapse: collapse;">
> > hostapd?</span></font><br><font face="arial, sans-serif"><span style="border-collapse: collapse;">></span></font><br></div><font face="arial, sans-serif"><span style="border-collapse: collapse;">> Not without modifying the source code. hostapd will enforce 20/40 MHz</span></font><br>
<font face="arial, sans-serif"><span style="border-collapse: collapse;">> coexistence rules based on the mandatory standard requirements.</span></font><br><br><font face="arial, sans-serif"><span style="border-collapse: collapse;">Also note that these restrictions don't just exist to annoy you -- if</span></font><br>
<font face="arial, sans-serif"><span style="border-collapse: collapse;">
you have BSSs that overlap in certain ways performance in both can</span></font><br><font face="arial, sans-serif"><span style="border-collapse: collapse;">severely degrade in both.</span></font><br>
<br><font face="arial, sans-serif"><span style="border-collapse: collapse;">johannes</span></font><br>