DUPlicate icmpv6 echo replies over wi0

[AT Matik]

On Monday 05 September 2005 10:17, 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

I am not sure if this is a 802.11 layer problem but a poor wireless 
connection. You get this on IPv4 as well. The accesspoint will 
retransmit automatically at lower speed when delivery is not 
confirmed within time. Same should happen on the wireless client, so 
indeed you have three player here where you may have connection 
quality problems.

You may set this 

net.inet.tcp.rexmit_min

higher to get better results on wireless networks with slower 
latencies but setting this will not resolve your connection problem. 
You should better check your antenas and AP settings.

Hans





> 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.

-- 


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