   PLUGIN USAGE
==================
ff_dat_plugin plugin by Henning Rogge

DAT = Directional Airtime Metric

This plugin calculates a nhdp link metric based on the approved
Freifunk ETX metric and the outgoing linkspeed. Compared
to the original ff_ett metric is just use the packet loss
calculated for the incoming traffic and not the product of
the loss-rate in both directions.

The linkspeed can be either queried directly from the
nl80211 plugin or can be set with the "linkspeed" option
in the interface section of the configuration.

The plugin assumes that the default (and minimal) linkspeed
is 1 MBit/s. If the link is faster than this, the total cost
is calculated by the ETX linkcost, divided by the linkspeed
in MBit/s (up to a linkspeed of 256 MBit/s).



   PLUGIN CONFIGURATION
==========================

[ff_dat_metric]
	interval      1.0
	window        64
	start_window  4
	ett           true

"interval" defines the time in seconds after which the ETT-metric is
recalculated. "window" is the number of memory slots (each "interval"
seconds long) that are used to smooth the ETX value.

"start_window" is the number of memory slots that are used at startup.
The number of slots is increased by 1 every interval so that a link can
quickly get up to a reasonable ETX value.

"ett" allows to switch off the linkspeed part of the metric calculation,
downgrading the metric to a directional ETT

