A communication device comprising: a first processing function for performing protocol processing of received datagrams; a second processing function for performing protocol processing for received datagrams at a higher level than the first processing function; and a power controller; the device being configured such that the power controller can place the second processing function in a low power state while the first processing function remains capable of performing protocol processing of received datagrams; and the first processing function comprising a mesh datagram processing function configured to process datagrams of a mesh protocol by analyzing received datagrams of the mesh protocol, determining a subset of those datagrams for retransmission, and causing the device to retransmit the determined ones of those datagrams.