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Date:      Fri, 15 Jun 2012 11:02:39 +0200
From:      Monthadar Al Jaberi <monthadar@gmail.com>
To:        Adrian Chadd <adrian@freebsd.org>
Cc:        freebsd-wireless@freebsd.org
Subject:   Re: AP <-> STA: tcpdump shows duplicate ARP request from STA, but STA only sends one.
Message-ID:  <CA%2BsBSoKBww4E=SA1xg6RqvLboOXLpWOyeKi2pLfWtaEwFUbKTA@mail.gmail.com>
In-Reply-To: <CAJ-VmonwquHPh%2BHcDDU0u1SNRf_eG6sRs_kVg-geaN=wGwUEsw@mail.gmail.com>
References:  <CA%2BsBSo%2BKF-OABC8v=3hPfn433Lhi2wkcP3Q%2B5Hu9H%2BHnpC2kGw@mail.gmail.com> <CAJ-VmonwquHPh%2BHcDDU0u1SNRf_eG6sRs_kVg-geaN=wGwUEsw@mail.gmail.com>

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On Mon, Jun 11, 2012 at 6:28 PM, Adrian Chadd <adrian@freebsd.org> wrote:
> Hi!
>
> The "null frame" is from hostap. It sends it out whenever a new
> station (re) joins. It's a broadcast frame that's harmless, designed
> to "seed" all the switches with the true location of the MAC address.
>
> As for dup packets, I'm not sure. Hm!

mm, its weird the received frame are only tapped once in net80211 from
what I can see ...

>
>
>
> Adrian

Ok, I tried with mesh and they dont recevie these ARP Request at all... hmmm

Running two RSPRO as mesh and one RSPRO as monitor I noticed this:

Both Mesh nodes sends out ARP Requests ( I verified it by tcpdump).

These ARP Requests are seen by the monitor RSPRO:
01:22:38.020700 1357460558us tsft 1.0 Mb/s -28dB signal -96dB noise
antenna 1 2442 MHz 11g MeshData (AE 0 TTL 31 seq 1) CF +QoS ARP,
Request who-has 192.168.0.22 tell 192.168.0.22, length 28
	0x0000:  0000 2000 6708 0400 4e34 e950 0000 0000  ....g...N4.P....
	0x0010:  2002 e4a0 0100 0000 8004 0000 8a09 071b  ................
	0x0020:  8802 0000 ffff ffff ffff 0015 6d67 2173  ............mg!s
	0x0030:  0015 6d67 2173 0000 00de 00de 001f 0100  ..mg!s..........
	0x0040:  0000 aaaa 0300 0000 0806 0001 0800 0604  ................
	0x0050:  0001 0015 6d67 2173 c0a8 0016 0000 0000  ....mg!s........
	0x0060:  0000 c0a8 0016                           ......

01:22:42.058109 1361496938us tsft 1.0 Mb/s -30dB signal -96dB noise
antenna 1 2442 MHz 11g MeshData (AE 0 TTL 31 seq 1) CF +QoS ARP,
Request who-has 192.168.0.23 tell 192.168.0.23, length 28
	0x0000:  0000 2000 6708 0400 6acb 2651 0000 0000  ....g...j.&Q....
	0x0010:  2002 e2a0 0100 0000 8004 0000 8a09 071b  ................
	0x0020:  8802 0000 ffff ffff ffff 0015 6d67 2175  ............mg!u
	0x0030:  0015 6d67 2175 0000 00de 00de 001f 0100  ..mg!u..........
	0x0040:  0000 aaaa 0300 0000 0806 0001 0800 0604  ................
	0x0050:  0001 0015 6d67 2175 c0a8 0017 0000 0000  ....mg!u........
	0x0060:  0000 c0a8 0017                           ......

I verified that each each mesh node have not recevied the ARP Request
by tapping the link level (tcpdump -i wlan0 -y IEEE802_11_RADIO). Are
they filtered out in the begining? Do we miss an interrupt?

br,
-- 
Monthadar Al Jaberi



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