The problem of paris traceroute in TCP

[xhdix]

Measurement: 39288974
Probe: 1002641

In paris traceroute mode, there are usually two duplicate hop:

I do not know how this can happen. (I have not read the code yet)

you can see it in all measurement of probe 1002641 on 2022-03-10:

all of which were in paris traceroute mode:

[PhilipHomburg]

Random question, is it possible that there are actually two nodes that have the same IP address? Your traceroute has a lot of RFC 1918 address and an IPv4 link local. All of those are not guaranteed to be unique.

[xhdix]

I don't think so. There is no same IP address in standard traceroute and RTTs are also the same. (Although, the first RTT is a bit strange.)
Also, they doing static routing.

https://atlas.ripe.net/measurements/39537917/#probes

[PhilipHomburg]

Ah. I see. It is possible that the packets of two measurements got mixed up.

[xhdix]

So this can also happen in standard traceroute?

[PhilipHomburg]

Hard to say. Paris traceroute and standard traceroute have a different way of storing parameters in packets