One of the key features introduced in ZigBee is full mesh networking, based on IEEE 802.15.4 peer-to-peer data transfer model. Routers are able to have child nodes and direct communication is possible between any FFD devices (coordinators and routers) within transmission range of each other. An end device can exchange data only with its parent node. Mesh networking is an optimum and dynamic routing with alternative paths. Because mesh topology routers can have alternative links for direct data transmission, a packet is transferred over the most suitable path in terms of reliability and transmission time.