Re: DUPlicate icmpv6 echo replies over wi0

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On 5 Sep 2005, at 15:17 PM, Greg Troxel wrote:

> The 802.11 mac layer can cause duplicates.  If the receiver hears the
> packet and sends an ack, but the ack is lost, the sender will
> retransmit, leading to two copies of the packet.  In theory a receiver
> could filter dups, but I haven't noticed code to do this.  So I would
> suggest trying with other traffic and seeing if it is really a
> ICMPv6-specific problem.  Your description makes it sound to me like
> something other than 802.11 MAC-layer dups are happening, though.  I
> would also suggest tcpdumping on the host behind the router and the
> hostap machine.


when pinging a host behind the access point/ router, the DUPs still  
happen,
but tcpdump on the pinged host reports only one reply for each request.

i should have mentioned that there is no problem whatsoever with
the client and another hostap (which is same hardware, same setup).
also, the antennas are about 5 cm away from each other, and i changed
the frequency to the one which worked with the other hostap, which did
not help at all. i dont think that a 802.11b retransmit would occur with
such predictablility and regularity, especially in my test environment.
(there are a _LOT_ of echo replies on the ether ;)

i have noticed that the machine which i suspect is causing the  
trouble has
a different station firmware version.
dmesg on the two good machines tells me:
     wi0: using RF:PRISM2 MAC:HFA3841 CARD:HWB3163 rev.A
     wi0: Intersil Firmware: Primary (0.3.0), Station (1.7.1)
while on the bad machine its
     wi0: using RF:PRISM2 MAC:HFA3841 CARD:HWB3163 rev.A
     wi0: Intersil Firmware: Primary (0.3.0), Station (0.8.3)

i dont even know what a station firmware does, but i can imagine this
being the guilty party.

so my next question would be:
how do i dump the firmware of a prism2 card in freebsd and
subsequently flash it on another host? :)

thnx,
/folkert




                                                                         
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