  Context. Large-amplitude oscillations (LAOs) of the solar prominences are
very spectacular but poorly understood phenomena. These motions have amplitudes
larger than $10 {\mathrm{\, km \,s^{-1}}}$ and can be triggered by the external
perturbations, e.g., Moreton or EIT waves.
  Aims. Our aim is to analyze the properties of large-amplitude oscillations
using realistic prominence models and the triggering mechanism by external
disturbances.
  Methods. We perform time-dependent numerical simulations of LAOs using a
magnetic flux rope model with two values of the shear angle and the density
contrast. We study the internal modes of the prominence using the horizontal
and vertical triggering. In addition, we use the perturbation that arrives from
outside in order to understand how such external disturbance can produce LAOs.
  Results. The period of longitudinal oscillations and its behavior with height
show good agreement with the pendulum model. The period of transverse
oscillations remains constant with height, suggesting a global normal mode. The
transverse oscillations typically have shorter periods than the longitudinal
oscillations.
  Conclusions. The periods of the longitudinal and transverse oscillations show
only weak dependence on the shear angle of the magnetic structure and the
prominence density contrast. The external disturbance perturbs the flux rope
exciting oscillations of both polarizations. Their properties are a mixture of
those excited by purely horizontal and vertical driving.
