Hello,
I am working on congestion control in IoT. I have found that CoAP is able to handle it. It works on UDP.
I have some question about MQTT.
1) Can MQTT able to handle congestion? If yes, then How?
2) MQTT uses TCP as a underlying transport protocol. It uses fully TCP or do some hacks in it and use it.
These questions are important for my work.
Thanks
Vishal
Hi Vishal Rathod,
1. Mqtt using TCP for communication because it requires a live connection to notify clients when a change made in the topic. Mqtt specially not use any congestion control mechanism but TCP can handle congestion control and flow control.
2. Yes, MQTT uses TCP/IP port 1883 for normal communication and 8883 for using MQTT over SSL. But there is the other one MQTT-SN (for Sensors) using UDP and here is the chance to drop packets and at that time it notify clients about congestion using return code. So MQTT-SN needs more attention than MQTT in congestion control mechanism.
Hi Vishal Rathod,
1. Mqtt using TCP for communication because it requires a live connection to notify clients when a change made in the topic. Mqtt specially not use any congestion control mechanism but TCP can handle congestion control and flow control.
2. Yes, MQTT uses TCP/IP port 1883 for normal communication and 8883 for using MQTT over SSL. But there is the other one MQTT-SN (for Sensors) using UDP and here is the chance to drop packets and at that time it notify clients about congestion using return code. So MQTT-SN needs more attention than MQTT in congestion control mechanism.
Hi Vardharajulu K N,
Thanks for helping.
Is there any possibilities for changing the code of TCP?
Means suppose I want to do some hacks in TCP (change some functionalities) and check that congestion happen or not.
I always thought that MQTT uses multicast since it is subscriber based model. Thanks for the info.
@Vishal: I don't know where you are going to change. You do Search for simulator, which allows to make changes in TCP or in real time refer your implementation platform that allow you to do this. Also, there are lots of network analyzing tools available to detect congestion in the network.
Yes, MQTT uses TCP/IP port 1883 for normal communication and 8883 for using MQTT over SSL. But there is the other one MQTT-SN (for Sensors) using UDP and here is the chance to drop packets and at that time it notify clients about congestion using return code. So MQTT-SN needs more attention than MQTT in congestion control mechanism.
Congestion control in MQTT? - ResearchGate. Available from: https://www.researchgate.net/post/Congestion_control_in_MQTT?tpr_view=iW3mCLTL416mufxNpum2iUNhz8XbjwP7Ever_3 [accessed Jan 17, 2017].
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