Note that PeerSim defines a global data structure (i.e. Network) where each peer is able to access the data structure of any other peer. However, in order to make a realistic simulation of a P2P system, it is required that each peer accesses only its data and the data of its neighborhood, which must be accessed through the Linkable Protocol and NOT through the Network data structure.
Furthermore, each node cannot estimate the size of the network through a single execution of the nextcycle method of the CDprotocol, but it waits for the replies from its neighbours which, in turn, will wait for the replies from their neighbours. In other words, the estimation of the size of the neworks require the execution of several simulation cycles, executed byseveral nodes.