Besides Wi-Fi® and Bluetooth®, the IEEE® 802.15.4 standard is another connectivity technology designed for low-rate wireless personal area networks. IEEE 802.15.4 chipsets are highly reliable, having shipped hundreds of millions of units since the standard was first ratified. They serve as the hardware foundation for many mesh networking layers, including Thread. Unlike other mesh networking protocols available, the Thread protocol is IP-based, so every device in the network is directly addressable.