[CUWiN-Dev] Beacon packets from tcpdump

[Bill Comisky]

On Fri, 19 Aug 2005, David Young wrote:

> On Fri, Aug 19, 2005 at 07:37:10PM -0500, Bill Comisky wrote:
>>
>> One more thing I've noticed with the very latest builds (0.5.8+) and the
>> 16-Aug snapshot BSD sources is that the number of beacons I'm seeing from
>> a 'tcpdump -ne -y ieee802_11_radio' is drastically reduced.  I had been
>> parsing the dump periodically to log signal levels, SSIDS, BSSIDS, etc.
>> I'm still seeing a typical flood of beacons from our neighbors' access
>> points, but those from our SSID relatively trickle in.
>
> You should see at most 10 beacons a second.  Station send beacons
> on a contention basis; the "losers" in the contention do not send a
> beacon.  It could be that your tcpdump station virtually always wins the
> contention, or else its neighbors' neighbors usually win.
>
> ISTR the latest net80211 code does a lot better of synchronizing the MAC
> clocks than the old.  That could affect the beacon generation in either
> direction: more or fewer beacons.

ok, that makes sense, since it did seem one node was sending out more than 
all the others.

> About how many cuwireless.net beacons do you see in a second?

I'll get some numbers next time I'm in the lab (gateway went down right 
after I left, so I can't get in at the moment).

bill

--
Bill Comisky
bcomisky at pobox.com