On Fri, Jan 17, 2025 at 9:58 AM Nicholas Pratte <npratte@iol.unh.edu> wrote:

>
> +    def assess_mtu_boundary(self, testpmd_shell: TestPmdShell, mtu: int)
> -> None:
> +        """Sets the new MTU and verifies packets at the set boundary.
> +
> +        Ensure that packets smaller than or equal to a set MTU will be
> received and packets larger
> +        will not.
> +
> +        First, start testpmd and update the MTU. Then ensure the new
> value appears
> +        on port info for all ports.
> +        Next, start packet capturing and send 3 different lengths of
> packet and verify
> +        they are handled correctly.
> +            # 1. VENDOR_AGNOSTIC_PADDING units smaller than the MTU
> specified.
> +            # 2. Equal to the MTU specified.
> +            # 3. VENDOR_AGNOSTIC_PADDING units larger than the MTU
> specified (should be fragmented).
> +        Finally, stop packet capturing.
> +
> +        Args:
> +            testpmd_shell: Active testpmd shell of a given test case.
> +            mtu: New Maximum Transmission Unit to be tested.
> +        """
> +        # Send 3 packets of different sizes (accounting for vendor
> inconsistencies).
> +        # 1. VENDOR_AGNOSTIC_PADDING units smaller than the MTU specified.
> +        # 2. Equal to the MTU specified.
> +        # 3. VENDOR_AGNOSTIC_PADDING units larger than the MTU specified.
> +        smaller_frame_size: int = mtu - VENDOR_AGNOSTIC_PADDING
> +        equal_frame_size: int = mtu
> +        larger_frame_size: int = mtu + VENDOR_AGNOSTIC_PADDING
> +
> +        self.send_packet_and_verify(pkt_size=smaller_frame_size,
> should_receive=True)
> +        self.send_packet_and_verify(pkt_size=equal_frame_size,
> should_receive=True)
> +
> +        current_mtu = testpmd_shell.show_port_info(0).mtu
> +        self.verify(current_mtu is not None, "Error grabbing testpmd MTU
> value.")
> +        if current_mtu and (
> +            current_mtu >= STANDARD_MTU + VENDOR_AGNOSTIC_PADDING and mtu
> == STANDARD_MTU
> +        ):
> +            self.send_packet_and_verify(pkt_size=larger_frame_size,
> should_receive=True)
>

I don't understand when this condition may be true - can you explain?
Thanks!


> +        else:
> +            self.send_packet_and_verify(pkt_size=larger_frame_size,
> should_receive=False)
> +
> +    @func_test
> +    def test_runtime_mtu_updating_and_forwarding(self) -> None:
> +        """Verify runtime MTU adjustments and assess packet forwarding
> behavior.
> +
> +        Test:
> +            Start TestPMD in a paired topology.
> +            Set port MTU to 1500.
> +            Send packets of 1493, 1500 and 1509 bytes.
>

I think 1493 should be 1491.


> --
> 2.47.1
>
>
Thanks, other than a couple questions here and in the associated patch this
looks good. I can merge on Tuesday.

Reviewed-by: Patrick Robb <probb@iol.unh.edu>
Tested-by: Patrick Robb <probb@iol.unh.edu>