In fact this could be linked to another thread -
https://forum.kitz.co.uk/index.php/topic,21833.msg376592.html#msg376592That Firebrick 6000 series ping box does I think do IP ICMP pings or PPP LCP pings and it must be the former in this case - can’t think straight just now, pain drugs, is that correct? (I am the latter being an AA ISP user.)
Basically what Kitz said, surely. The consensus from that other thread is that this is bogus and there is no solution available for the likes of us but there is a proper one for corporate users.
I don’t know if the other option, PPP LCP pings is better or worse. If LCP ping is treated as high priority then the result may be what they want to see or the opposite. In the general case, either you want to measure the link alone or you want to measure link plus queuing time resulting from the traffic that currently happens to be present.
If your router treats a huge lot of ICMPs as an attack then it would throw them away. But I wouldn’t have thought this is relevant here as they are spaced out.
Perhaps we need a new RFC or two, one with explicit definition of performance measurement goals and rules about handling of the responses.