Neighbor Discovery Proxy-Gateway for 6LoWPAN-based Wireless Sensor Networks : Design, Implementation, Analysis, and Evaluation
The IETF 6LoWPAN working group has defined a number of optimizations to adapt the traditional IPv6 Neighbor Discovery protocol to non-transitive wireless links. While these optimizations result in a more efficient use of the resources of hosts within a 6LoWPAN network, they introduce a number of impediments for communication between nodes in traditional IPv6 networks and nodes in 6LoWPAN networks. This document describes how to overcome these obstacles by providing the necessary proxy mechanisms, leading to a transparent, seamless, and cost-effective integration of 6LoWPAN nodes into existing IPv6 network infrastructures. In particular, this document details the requirements, specification, and implementation of an embedded device responsible for such integration: a 6LoWPAN Neighbor Discovery Proxy- Gateway (6LP-GW).
Moreover, this report demonstrates that integrating 6LoWPAN nodes into existing IPv6 networks by means of a 6LP-GW as described here is both feasible and convenient in most situations. This convenience can be observed from both the network and the end-user perspectives:
From the network’s point of view, the solution proposed here integrates 6LoWPAN into an existing IPv6 network. Hence, 6LoPWAN nodes and traditional IPv6 devices can coexist within the same IPv6 subnet, sharing the same network prefix. Furthermore, enabling such integration and coexistence is simple and inexpensive in contrast to other solutions. The main reason for this simplicity is that the 6LP-GW is completely transparent from both the network layer and the neighbor discovery protocol’s perspective: while each type of node still takes advantage of its own specific neighbor discovery protocol’s features, all of them share the same IPv6 subnet and no node in the network is able to determine the nature of its neighbors (simply on the basis of the neighbor discovery protocol).
Each of the above advantages leads to an immediate benefit from the endusers’ perspective: the integration of the 6LoWPAN network into the existing infrastructure, frees the user from having to acquire an expensive (and so far rare) border router. Instead, the end-user simply buys a 6LP-GW which, as previously mentioned, is inexpensive compared to the former; the 6LP-GW broadens the existing IPv6 router’s functionality (in contrast to a 6LBR which would replace it). In addition, it is important to mention that using a 6LP-GW could not be simpler; once attached to an IPv6 router’s LAN port, no further intervention is required.
As result, the solution proposed here undoubtedly eases and speeds up the deployment process of 6LoWPAN, enabling immediate use by even the most inexperienced user.
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