1. In a mesh network having an end node operable in a sleep mode and an awake mode, an energy-efficient method of transmitting data from the end node to a destination node, comprising:transmitting a first message, the first message including a tag ID of the destination node and message data, from the end node to a parent node of the end node, wherein the tag ID represents an identifier of the destination node that differs from a network address of the destination node assigned by the mesh network;
receiving, at the end node, a first acknowledgement from the parent node acknowledging receipt of the first message by the parent node;
causing the end node to enter sleep mode in response to the first acknowledgement;
in response to determining that the parent node is not the destination node:
performing, at a node other than the end node, a discovery procedure that identifies the network address of the destination node based on the tag ID;
performing, at the node, a routing procedure that transmits a second message, comprising the first message, to the destination node based on the network address and receives, at the parent node, a second acknowledgement acknowledging receipt of the first message by the destination node; and
in response to an indication that the end node has awakened from the sleep mode, transmitting, by the parent node, the second acknowledgement to the end node.