Due to the lack of IP support, the ZigBee protocol stack for IEEE 802.15.4 low rate wireless personal area networks (LR-WPANs) is the perfect solution for closed, ad-hoc environments. However, we can envisage also open and interconnected application scenarios, such as the Internet of Things or the integration of ZigBee/IEEE 802.15.4 nodes in mobile/smart phones, that would greatly benefit from the IP support. The LoWPAN adaptation layer proposed by the 6LoWPAN IETF working group to enable the transmission/reception of IPv6 data in IEEE 802.15.4 networks may be regarded as the first step towards the direction of IP direct support into IEEE 802.15.4 nodes. However, a fully fledged solution to be used in the scenarios outlined above still lacks the following functionality: i) self-configuring address assignment mechanism; ii) multi-hop routing protocol; iii) support of Internet-compliant transport protocols; iv) self-configuring network and service discovery. It may seem trivial to provide such functionality in an IP world, as off the shelf solutions could be adopted; however, this is not an easy task, given the very limited hardware capabilities of IEEE 802.15.4 devices. In this paper we define a complete protocol architecture and specific self-configuring mechanisms to support the aforementioned functionality over IEEE 802.15.4 devices, taking into account their hardware constraints. We also present an implemented test-bed which demonstrates the functionality of the proposed solution in a real application scenario. ©2010 IEEE.