On 21 Oct 2023, at 17:04, Frode Nordahl wrote:
> Many system tests currently use ping with the combination of a
> low packet count (-c 3), short interval between sends (-i 0.3)
> and a _deadline_ of 2 seconds (-d 2).
>
> This combination of options may lead to a situation where more
> than count packets are sent however ping will stop when count
> packets are received. This results in a failed test due to how
> the result is checked, for example:
>
> ping6 -q -c 3 -i 0.3 -w 2 fc00::3 | FORMAT_PING
> @@ -1,2 +1,2 @@
> -3 packets transmitted, 3 received, 0% packet loss, time 0ms
> +4 packets transmitted, 3 received, 25% packet loss, time 0ms
>
> To reiterate, in the above example there is no packet loss, but
> ping stops after _receiving_ 3 packets, not bothering with
> waiting for the response to the fourth packet it just sent out.
>
> If we look at the iputils ping manual for the -w deadline option
> we can read that this is expected behavior:
>
>> Specify a timeout, in seconds, before ping exits regardless of
>> how many packets have been sent or received. In this case ping
>> does not stop after count packet are sent, it waits either for
>> deadline expire or until count probes are answered or for some
>> error notification from network.
>
> To avoid these kinds of failures in checks where a response is
> expected, we replace ping -w with ping -W.
>
> We keep ping -w for checks where it is expected to NOT get a
> response.
>
Thanks for the patch, the change looks good to me, and seems to pass the dp
tests.
Acked-by: Eelco Chaudron <[email protected]>
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