  In the context of fog computing, we consider a simple case when data centers
are installed at the edge of the network and assume that if a request arrives
at an overloaded data center, then it is forwarded to a neighboring data center
with some probability. Data centers are assumed to have a large number of
servers and that traffic at some of them is causing saturation. In this case
the other data centers may help to cope with this saturation regime by
accepting some of the rejected requests. Our aim is to qualitatively estimate
the gain achieved via cooperation between neighboring data centers. After
proving some convergence results, related to the scaling limits of loss
systems, for the process describing the number of free servers at both data
centers, we show that the performance of the system can be expressed in terms
of the invariant distribution of a random walk in the quarter plane. By using
and developing existing results in the technical literature, explicit formulas
for the blocking rates of such a system are derived.
