  In this paper, we will study the long time behavior of the simple symmetric
exclusion process in the ``channel'' $\Lambda_N=[1,N]\cap \mathbb{N}$ with
reservoirs at the boundaries. These reservoirs are also systems of particles
which can be exchanged with the particles in the channel. The size $M$ of each
reservoir is much larger than the one of the channel, i.e. $M=N^{1+\alpha}$ for
a fixed number $\alpha>0$. Based on the size of the channel and the holding
time at each reservoir, we will investigate some types of rescaling time.
