Unable to forward PacketIn messages to ONOS controller from Tofino switch

[endrigoshi]

Dear all,

I am currently working on a project where we will use ONOS to control a Tofino1 switch. However, I am having problems in receiving PacketIn messages at ONOS, while adding rules to Tofino works fine.

The Tofino platform being used is Wedge100BF-32qs, SDE version is 9.7.2 and Stratum running as a docker container (stratumproject/stratum-bfrt:latest-9.7.2); while on the other side I am running ONOS 3.0.0. The Tofino switch and the PC where ONOS is running are both connected to a L2-switch. Moreover, I have another PC that that has two interfaces connected to port 7/0 (308) and 16/0 (0) of Tofino.

I have tried different matching rules that invoke a "send_to_cpu()" action, but I have seen that in no case I am able to see the PacketIns arrive on the ONOS side. Considering the Tofino platform that I am using, I have set CPU_PORT=192 (I have tried both options: setting it directly in the .p4 code and also providing the -DCPU_PORT=192 flag during compilation).

The "copy_to_cpu()" action is defined as below:

action copy_to_cpu() {
    ig_intr_md_for_tm.ucast_egress_port = CPU_PORT;
    hdr.packet_in.setValid();
    hdr.packet_in.ingress_port = (BasicPortId_t)basic_md.bridged.base.ig_port;
    table0_counter.count();
    }

From ONOS, I add a rule that matches on the ETH_TYPE and if its ARP it triggers the copy_to_cpu() action above. I have noticed that Tofino is not able to set the egress_port to 192, which leads to egress_port=0. The counters in the flow rule suggest that the packet is indeed matched, while the port counters show that it is sent out of port 0 (which in this case is port 16/0) and I can confirm this using Wireshark. The same behavior happens even when I write "192" instead of "CPU_PORT" in line 2 of the above snippet. If instead I set the egress_port to 308 (meaning port 7/0), I can see the packet received correctly on the other interface.

I would appreciate any insight on whether I am doing something wrong with the setup, or if I forgetting some configuration that can enable Tofino to send the PacketIns to ONOS.

Best regards,
Endri