As such, stacking n {\displaystyle n} MPNN layers means that one node will be able to communicate with nodes that are at most n {\displaystyle n} "hops" away. In principle, to ensure that every node receives information from every other node, one would need to stack a number of MPNN layers equal to the graph diameter. However, stacking many MPNN layers may cause issues such as oversmoothing[24] and oversquashing.[25] Oversmoothing refers to the issue of node representations becoming indistinguishable.