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Re: Improving the data supplied by BPF



No, I am really looking for packet data, but perhaps packet metadata a
la DLT_IEEE802_11_RADIO.  As a first step, I want the data source
labeled, so I can know if I have queueing delays or not.  The point of
tapping at tx complete is that you can find out how many retries were
used and what the actual rate for that packet was (sometimes an 802.11
interface will drop back to 1 Mb/s after failing to get an ack at the
chosen rate), or if no ack was received.  I wanted this data to compute
the ETX metric

  http://pdos.csail.mit.edu/papers/grid:mobicom03/paper.pdf
  http://pdos.csail.mit.edu/decouto/abstract.html

which is otherwise a bit hard to get.  I was relatively unconcerned
about processing overhead and how the software was functioning etc.  In
my case I added a new 'tracerecord' DLT that had a metadata record for
each packet with the at-tx-complete stats.

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