  Interplanetary shocks are one of the crucial dynamic phenomena in the
Heliosphere. They accelerate particles to high energies, generate plasma waves,
and can trigger geomagnetic storms in the terrestrial magnetosphere disturbing
significantly our technological infrastructures. In this study, two IP shock
events are selected to study the temporal variations of the shock parameters
using magnetometer and ion plasma measurements of the STEREO$-$A and B, the
Wind, Cluster fleet, and the ACE spacecraft. The shock normal vectors are
determined using the minimum variance analysis (MVA) and the magnetic
coplanarity methods. During the May 7, 2007 event, the shock parameters and the
shock normal direction are consistent. The shock surface appears to be tilted
almost the same degree as the Parker spiral, and the driver could be a
Co--Rotating Interacting Region (CIR). During the April 23, 2007 event, the
shock parameters do not change significantly except for the shock $\theta_{Bn}$
angle, however, the shape of the IP shock appears to be twisted along the
perpendicular direction to the Sun-Earth line as well. The driver of this
rippled shock is Stream Interaction Regions (SIRs)/CISs as well.
