Configured Transmit Queue Length. Values other than zero over-ride
the router selected values. A value of zero has a special meaning.
Zero causes router based default values to be used. All values are
accepted. Care should be taken not to set this to a value which is
much greater than the default. The default can be read out of the
wfLoigcalLineTxQueueLength attribute when the router is running with
this attribute set to zero. Sets to this attribute may take up to
one minute to take effect.