[Bloat] [aqm] ping loss "considered harmful"

Curtis Villamizar curtis at ipv6.occnc.com
Thu Mar 5 13:56:33 EST 2015

In message <CAA93jw4F7iffbTRUt5RFsF0wgoOAXPUVHdu7JESVq4uM17cm7A at mail.gmail.com>
Dave Taht writes:
> My point was A), I have seen tons of shapers out there that actually
> prioritize ping over other traffic. I figure everyone here will agree
> that is a terrible practice, but I can certainly say it exists, as it
> is a dumb mistake replicated in tons of shapers I have seen... that
> makes people in marketing happy.
> Already put up extensive commentary on that bit of foolishness on
> "wondershaper must die".

Its possible to detect such a shaper prioritizing ICMP echo/reply by
doing a an HTTP fetch concurrent with a ping and then and see if the
TCP data packet get significantly delayed relative to the ICMP echo
and echo reply packets.  You'd have to do a tcpdump and match the ICMP
echo to the echo reply and see if later the ICMP RTT looks very
different from the TCP RTT.  It might be that the SYN and SYN ACK are
not delayed but the plain old TCP date packets are.

If anyone has a small amount of spare time and wants to put together a
shell script its certainly doable.


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