Today, there exist several standards based and proprietary based protocols that can be used in Wireless Sensor Network (WSN) applications. Proprietary technologies are difficult to integrate into larger networks and currently available Internet-based services. The use of IP based technologies allows easy integration with existing network infrastructure. Interoperability has always been a major concern within the IETF. The previous work has proved that the IPv6 Routing Protocol for Low-power and Lossy Networks (RPL) protocol, proposed by the IETF is interoperable in widely used TinyOS and Contiki platforms. Compared to the previous work, this work highlights the detailed analysis of the behaviour of RPL in these two platforms, in terms of comparison with two objective functions used (MRHOF and OF0), analysis of RPL control messages (DIO, DIS and DAO) and finally the tolerance of RPL performance under varying traffic loads (1 packets per minute to 60 packets per minute). Further, this work gives a detailed insight into implementation specific issues as reasoning for the degradation of the RPL performance, when mixing nodes of TinyOS and Contiki.