Experimental observation of RPL: routing protocol overhead and asymmetric links

This document summarizes our observations of the behavior of RPL on a testbed composed of tens of IEEE 802.15.4 nodes. Our first observation is that the continuous task of estimating the link metric to all candidate neighbors causes a significant background load. This traffic is persistent, even in a stable network where DIO transmissions are eventually widely spaced. Next, this document focuses on the case of the presence of an asymmetric link, due to either a muted or a deaf node. In these circumstances, the standard RPL mechanisms may well generate hundreds of routing messages per node and per hour.