  This work analyses the properties of groups of galaxies in the surroundings
of clusters. On the basis of a very large public Virgo Consortium Simulation,
we identified systems of galaxies in a wide range of masses. Systems with
masses greater than $ M_{cut}= 4 \times 10^{14} M_{\odot} h^{-1} $ are
considered "host", whereas smaller systems are taken as groups. Our results
show that groups properties are affected by the proximity of massive hosts.
Physical properties such as velocity dispersion, internal energy ($E$) and
virial radius, show an increment, whereas the mean density decreases as the
host-group distance is smaller. By analysing groups with different properties,
we find that the low mass and the weakly bounded ($E > 0$) subsamples, are
strongly affected by the presence of the host; on the other hand, massive
groups and groups with $E < 0$ do not show dependence on the host-group
distance. Using a sample of groups identified in the final version of the 2dF
Galaxy Redshift Survey, we find a very similar velocity dispersion behaviour in
the observational data compared to results in the simulation. We also study the
dependence of the groups velocity dispersion on the host masses in both,
observations and simulation; finding that the larger is the host mass the
higher is the effect on its vicinity.
