Abstract: Techniques and devices for determining a preferred physical layer for communication by a node in a Thread network are described. The node transmits a first IPv6 over Low power Wireless Personal Area Networks, 6LoWPAN, frame to a neighbor node using a first physical layer and transmits the first 6LoWPAN frame to the neighbor node using a second physical layer. The node determines a first preference value for the neighbor node using the first physical layer and determines a second preference value for the neighbor node using the second physical layer. The node compares the first preference value and the second preference value to determine the preferred physical layer for communication and transmits a second 6LoWPAN frame to the neighbor node using the preferred physical layer.