As part of Internet of Things, low-power lossy network (LLN) applications are being diversified, which requires LLNs to support diverse traffic patterns. In this paper, we address performance issues of IPv6 routing protocol for LLNs (RPL) when delivering various traffic patterns. Specifically, we show that RPL was designed to mainly support upward traffic, and thus cannot construct reliable multi-hop routes for downward traffic-centric applications. To solve the problem effectively, we provide an improved RPL implementation, termed DT-RPL , which fast updates wireless link quality through both upward and down-ward traffic to support Diverse Traffic patterns. It is enabled to update routes in dynamic link environments regardless of traffic patterns. Our results in a multi-hop testbed over IEEE 802.15.4 links reveal that our scheme significantly improves RPL¡¯s performance in various traffic scenarios, in terms of packet delivery ratio, control overhead and radio energy consumption.