Cannot connect and not forward properly after adding switch role(with mininet) about behavioral-model HOT 3 CLOSED

I don't see anything with your code snippet. Usually, not being able to connect to the switch with the runtime_CLI means that the switch has crashed. A few things can cause the switch to crash (e.g. out-of-bound register access during packet processing).
You can check if the switch crashed by checking if the switch process started by Mininet is still alive (grep for simple_switch in the ps output).
If you need help, please provide a full P4 program (which can be compiled) as well as CLI commands.

from behavioral-model.

Seems that the problem occurs due to the intrinsic_metadata.
I try to add all field in C++ to the meta data instead of only "switch_role" then everything seems working.
But I do not understand why, can you explain briefly why I can make it work like this?

header_type intrinsic_metadata_t {
    fields {
        mcast_grp : 4;
        egress_rid : 4;
        mcast_hash : 16;
        lf_field_list : 32;
        resubmit_flag : 16;
        switch_role:4;
    }
}

from behavioral-model.

You are not supposed to use intrinsic_metadata to store your own metadata. Sorry for missing that in the snippet you submitted. Please use something like this:

header_type user_metadata_t {
    fields {
        switch_role : 4;
    }
}
metadata user_metadata_t user_metadata;

The names user_metadata_t / user_metadata are not important, you can use whatever you want so long as it is not intrinsic or standard. intrinsic_metadata fields have a special meaning for the switch, and you should not try to modify them. More information here: https://github.com/p4lang/behavioral-model/blob/master/docs/simple_switch.md

However, I think that the switch should probably not crash in your case, and I'll leave this issue open until I have time to try and improve it.

from behavioral-model.