  We study a system of $N$ interacting particles on $\bf{Z}$. The stochastic
dynamics consists of two components: a free motion of each particle
(independent random walks) and a pair-wise interaction between particles. The
interaction belongs to the class of mean-field interactions and models a
rollback synchronization in asynchronous networks of processors for a
distributed simulation. First of all we study an empirical measure generated by
the particle configuration on $\bf{R}$. We prove that if space, time and a
parameter of the interaction are appropriately scaled (hydrodynamical scale),
then the empirical measure converges weakly to a deterministic limit as $N$
goes to infinity. The limit process is defined as a weak solution of some
partial differential equation. We also study the long time evolution of the
particle system with fixed number of particles. The Markov chain formed by
individual positions of the particles is not ergodic. Nevertheless it is
possible to introduce relative coordinates and to prove that the new Markov
chain is ergodic while the system as a whole moves with an asymptotically
constant mean speed which differs from the mean drift of the free particle
motion.
