A Survey of Limitations and Enhancements of the IPv6 Routing Protocol for Low-power and Lossy Networks: A Focus on Core Operations <s> C. Routing Maintenance (Trickle Timer) <s> We present Trickle, an algorithm for propagating and maintaining code updates in wireless sensor networks. Borrowing techniques from the epidemic/gossip, scalable multicast, and wireless broadcast literature, Trickle uses a "polite gossip" policy, where motes periodically broadcast a code summary to local neighbors but stay quiet if they have recently heard a summary identical to theirs. When a mote hears an older summary than its own, it broadcasts an update. Instead of flooding a network with packets, the algorithm controls the send rate so each mote hears a small trickle of packets, just enough to stay up to date. We show that with this simple mechanism, Trickle can scale to thousand-fold changes in network density, propagate new code in the order of seconds, and impose a maintenance cost on the order of a few sends an hour. <s> BIB001 </s> A Survey of Limitations and Enhancements of the IPv6 Routing Protocol for Low-power and Lossy Networks: A Focus on Core Operations <s> C. Routing Maintenance (Trickle Timer) <s> The Trickle algorithm allows wireless nodes to exchange information in ::: a highly robust, energy efficient, simple, and scalable manner. ::: Dynamically adjusting transmission windows allows Trickle to spread ::: new information on the scale of link-layer transmission times while ::: sending only a few messages per hour when information does not change. ::: A simple suppression nechanism and transmission point selection allows ::: Trickle's communication rate to scale logarithmically with density. ::: This document describes Trickle and considerations in its use. <s> BIB002
One of the key design principles of the RPL is minimizing the routing control overhead and signaling cost in order to reduce energy consumption and enhance reliability. In this regard, RPL employs the Trickle algorithm BIB001 [69] to govern the transmission of the signaling traffic used to construct and maintain the DODAG. The basic idea behind Trickle is to adjust the frequency of message transmission based on network conditions. Trickle relies on two simple mechanisms to disseminate routing information efficiently. The first is to change adaptively the signaling rate according to conditions currently present in the network BIB001 . Specifically, Trickle increases the transmission rate when a change in routing information is discovered (i.e. an inconsistency is detected) as a mean to populate the network rapidly with up-to-date information BIB001 BIB002 . As the network approaches its steady phase, Trickle exponentially reduces the transmission rate to limit the number of transmissions when there is no update to propagate. The second mechanism used by Trickle is the suppression mechanism in which a node suppresses the transmission of its control packet if it detects that enough of its neighbors have transmitted the same piece of information, thus limiting redundant transmissions BIB001 BIB002 .