Can I install rules like this？

Education Working Group
1

Hello,
I’m a beginner of P4 and here is my question.
I want to check the match-action table if the rule is exist when the first packet of a new flow arrives. If the rule is not there, I want to send the packet to control plane and the control plane to parse the packet then install new rules. Can P4 do this?
Thank you

2

Hi,

You should be able to do that. You can find some examples at jafingerhut/p4-guide like this one or this one. It is always good to search for controller_header in P4 programs to identify similar examples. You then need the control plane that can receive those packets and process them. I generally recommend ONOS, which has a nice tutorial here but there is a steep learning curve if you have never used it before. Else, you can try to use the Python control plane included in the P4 tutorials. It needs some modifications, but I just searched on Github and you can find some code here by Kevin Cyu, here by Belma Turkovicor some I did some time ago.

I hope it helps

3

Thank you very much!!! I will check these for more. : )