1. PHY - 802.15.4 
2. MAC - 802.15.4 - MAC
3. Network - MANET (DSR, AODV, OLSR, ZRP), RPL
4. Transport - UDP
5. Applications 

IoT devices used in NetSim are Sensors, 6LoWPAN Gateway, Routers, Switches, Hosts etc.

Related articles:

can-you-provide-a-brief-over-of-netsim-s-iot-library-

is-rpl-protocol-available-in-netsim-

More details of the IOT simulation specifications are available at https://tetcos.com/iot-wsn.html