This chapter is from the book
2.5 Depth of a Network, Number of Children, and Network Address Allocation
Depth of a network: The depth of a network is determined by the number of routers (hops) from the coordinator to the farthest device, where farthest is defined by number of hops. In a star topology, the depth of a network is one.
Number of children: The number of end devices (children) that are connected to a router or coordinator. The coordinator sets the maximum number of children connected to a router.
Address allocation: In a tree topology, each coordinator holds information about the network, such as the maximum number of children (the number of end devices connected to each router), maximum number of routers, and uses this information to assign an address to each router. The routers, then, assign the addresses to their respective end devices (children). In a mesh topology, however, each router assigns a random address to its respective end devices.