Radio environment visualization in cooja

Question

What does a red arrow from one mote to another in cooja simulator means? Generally radio traffic is shown in the form of blue arrows, what does a red arrow signifies? In my case one of my motes in the simulation is not receiving any incoming ip packets after this event. I am using contiki-2.7

Answer 1

To follow your example, a red arrow means that the node n°2 sent a message which is likely to be received by the node n°1. In other words, the node n°1 is in the range of the node n°2, but that doesn't mean that it has successfully received the message (maybe because the radio was off at this moment or anything else). If you had an ACK mechanisms in your protocol, you should be able to see that a message is correctly received by one node by seeing a double arrow in the network view.

You may also want to turn the timeline on (tools -> timeline) in order to see information about TX - Rx status of each nodes.

Regards,

Answer 2

Citation: Two simultaneous transmissions to a node, which results in radio interference, is shown in red. Source article for reference