Sending extra information to controller in packet_in header

[Radhakrishna Kamath]

Hey Everyone,

I am working on a flow classification problem in the datacenter and I want to send the result of the classification to the controller. I saw that packet_in goes to the controller and ONOS read that header and retrieves ingress_port.

I modified the packet_in header and added a 16-bit value, which I will change when a certain condition is met. But it is not getting reflected in the controller. I printed the packet_in operation in InterpreterImpl.java file but I didn't see any change.

Then I removed the check and set it always. I added that line in the egress pipeline of p4 code where ingress_port is updated. But still, I am not able to see any change. It is taking it as 0x0.

Can anyone please explain to me, what is the problem or how to send information to the controller? I searched for a similar post in this group and I got a discussion from 2018 which tells me thatpacket_in header carries metadata to the controller, but I am not able to use it for my problem.

Hope to listen soon. Thanks in advance.