The Subscribed message is simple,It contains a unique packet identifier and a list of subscriptions.
To subscriber received a publish message based on a topics of interest.
Then the Subscriber sends Subscribed message to the MQTT broker.
Open a Source file in the following location. >> contiki-ng/examples/mqtt-client/mqtt-client.c Code : mqtt-client.c
Run the Simulation
MQTT broker window
MQTT Subscriber window
Mote Output