Re: how to make the sniffer quicker?

["Asier Martinez" <axierr () gmail com>]

Hi David,
the problem is not in the sniffer is in the 802.11 medium itself,
when  you use -f you lost a lot of packets ( in Ethernet is similar )
before they arrive to the network, they lost in the card buffer
because the 802.11 ACK - RTS/CTS mechanism is too slow.

Regards,



2007/1/17, David Lopez <David.Lopez () cit ie>:
> Hi
>
>
>
> I'm developing a position system for my PhD.
>
> This system is based on Round Trip Time measurements.
>
> I'm getting the timestamp of the packets using Tethereal and the Mactime
> in the Prism Monitor Header
>
>
>
> My problem is: the sniffer is too slow.
>
> When I'm flooding the receiver with pings, using the linux command ping
> -f, if I send X in one second I cannot get this number of packets in the
> sniffer, I always get less, around the 10%.
>
> It is like the sender is quicker generating than the sniffer capturing
> them.
>
> How can I improve the number of capture packets per second in the
> sniffer?
>
>
>
> The sequence that I'm sending and trying to capture is a ping sequence
> using Request to send/Clear to send, so the whole sequence is:
>
> -Request to send
>
> -Clear to send
>
> -Request (ping)
>
> -Acknowledge
>
> -Reply (ping)
>
> -Acknowledge
>
>
>
> I'm only interested in the RTS and CTS timestamps, can I filter out the
> Request, Reply and Ack packets using tcpdump filters in Tethereal? Maybe
> in this way Ill be quicker
>
>
>
> All the best
>
>
>
> David
>
>
>
>
>
>
>
>
>
>
>
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