The value of tmnxL2tpLnsTuPppProxyAuth specifies
if this system re-uses the authentication done by the proxy (LAC).
If the value of this object is 'always', the Authentication AVPs received
from the LAC are accepted.
If the value of this object is 'never', this system restarts the
authentication of the remote system.
The value 'default' specifies that the actual value must be used
of the object tmnxL2tpLnsTgPppProxyAuth.