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 From:  Jim Thompson <jim at netgate dot com>
 To:  Denilson Rocha <denilson at vertentes dot com dot br>
 Cc:  Michael J Hess <mhess at nighthawkrad dot net>, m0n0wall at lists dot m0n0 dot ch
 Subject:  Re: [m0n0wall] Is there some interface prioritized?
 Date:  Thu, 02 Feb 2006 07:23:55 -1000
Denilson Rocha wrote:

> Hi!
>
> Mike, you really solved my problem! All the links were in channel 1... 
> Changed the P2P do channel 6, and all works fine now!
>
> It's interesting how we work on a solution, and forget the elemental 
> things.... I remember that  I have done an alteration in these 
> channels, but after some tests I forgot this way, and began to search 
> another things... The channels are always in my mind, but this time...


This is the m0n0wall list, not "WiFi RF 101", but I must say:

You probably have better throughput with the cards on a single channel 
than you do with two cards on different channels in the same band.

Reason:

Incoming packets will set CCA (preventing transmission for the duration 
of the packet) on both radios, preventing radio 'B' from smashing the 
incoming packet on radio 'A'.

If radio 'A' and 'B' are on channels 1 and 6, then an incoming packet on 
'A' can be smashed if 'B' transmits.  Also an incoming packet on 'B' can 
be smashed if 'A' transmits.

Same thing for channels 6 and 11.  The problem is less evident running 
on channels 1 and 11, but still present.

There are ways to reduce the effect, but they mostly involve (expensive) 
filtering.

Jim