[atlas] Measurement question

Hello Roberto,

I’ve done the exact same measurement too, using the 3 types of traceroute available (ICMP, UDP and TCP).
UDP:
(https://atlas.ripe.net/measurements/49826077/#general)



TCP:
(https://atlas.ripe.net/measurements/49826078/#general)


ICMP:
(https://atlas.ripe.net/measurements/49826076/#general)


The way the traceroute works in Atlas is that if 5 hops have been received without response, the trace skips over to TTL 255 and ends the traceroute. This is what you see with TCP and ICMP. The traceroute stops for lack of response. To prove that, I’ve run the trace again, skipping hops 1-7, for both ICMP and TCP:

https://atlas.ripe.net/measurements/49826868/#general


https://atlas.ripe.net/measurements/49826959/#general


Now for the interesting bits:
100.64.0.0/10 is CGN (Carrier Grade NAT), RFC 6598.
Looking at the traceroute differently:
Hop 1 (AS16509, Amazon EU West, Amazon-02)
Hop 2-7 CGN
Hop 8-9 (AS unknown, but between UK and US, IPROU3-ARIN, so Amazon IP routing 3)
Hop 10 (AS unknown, but between UK and US, IPROU3-ARIN/ARMP-ARIN, Amazon IP routing)
Hop 11-15 CGN
Hop 16 (AS unknown,  presumably US, IPROU3-ARIN/ARMP-ARIN, I presume Amazon IP routing still)
Hop 17-19 CGN
Hop 20 (AS13335, Cloudflare US)

So it seems like every cloud zone interconnect (amazon Europe west, US, then Cloudflare) transitted goes through a CGN setup. Not sure but I can understand if this confuses some types of traffic.

I don’t think there’s anything wrong with your setup, but the results are interesting. I’ve copied a couple of our researchers onto the mail as they may be interested in this as well.

Regards,

Michel

> On 8 Feb 2023, at 11:33, roberto.lucignani at caleidos.it wrote:
> 
> Hi Michael,
> for example, one measure ID is this one: 49813750
> The result says there are 7 HOPS.
>  The result of the traceroute made directly on the host is the following one
>  traceroute to www.madghigno.tech (172.67.221.209), 30 hops max, 60 byte packets
> 1  52.56.0.19  24.303 ms 52.56.0.31  9.067 ms 52.56.0.17  29.663 ms
> 2  * 100.65.18.192  7.843 ms 100.65.19.176  6.252 ms
> 3  100.66.8.254  1.563 ms 100.66.8.146  0.697 ms 100.66.8.168  1.449 ms
> 4  100.66.10.138  8.469 ms 100.66.10.14  5.713 ms 100.66.10.6  8.127 ms
> 5  100.66.7.77  1.653 ms 100.66.6.173  2.658 ms *
> 6  100.66.4.75  2.726 ms 100.66.4.87  2.327 ms 100.66.4.89  1.550 ms
> 7  100.65.10.65  0.533 ms 100.65.11.1  0.857 ms 100.65.10.161  8.616 ms
> 8  15.230.158.29  2.062 ms 15.230.158.171  5.998 ms 15.230.158.27  1.617 ms
> 9  15.230.158.164  1.315 ms 52.94.33.120  2.089 ms 15.230.158.40  1.484 ms
> 10  54.239.101.83  1.440 ms 150.222.65.23  1.358 ms 54.239.101.87  1.897 ms
> 11  100.91.211.7  1.368 ms 100.91.13.66  1.956 ms 100.91.13.100  5.077 ms
> 12  100.91.210.16  1.837 ms 100.100.6.119  1.848 ms 52.93.134.81  2.178 ms
> 13  100.100.73.70  2.434 ms 100.91.203.106  4.546 ms 100.100.85.70  1.139 ms
> 14  100.91.207.15  1.289 ms * 100.100.72.67  1.767 ms
> 15  100.100.2.76  3.616 ms 100.91.201.140  1.955 ms 100.91.205.18  1.744 ms
> 16  99.83.89.19  6.820 ms 100.91.201.1  2.454 ms 100.91.201.97  2.415 ms
> 17  100.91.211.89  17.823 ms 172.71.176.2  3.200 ms 172.70.160.2  4.450 ms
> 18  100.100.6.77  1.805 ms 100.100.6.3  1.943 ms 100.100.6.111  2.005 ms
> 19  100.100.80.70  1.980 ms 100.100.76.134  2.679 ms 100.100.69.134  2.081 ms
> 20  172.67.221.209  2.799 ms 100.100.89.209  7.318 ms 100.100.89.17  6.869 ms
>  Since the website is served by cloudflare the route may vary between requests but the are always around 18/20 HOPS
>  I don’t understand if I0m missing something here. Let me know if you need further details
>   Regards,
> Roberto
>   From: Michel Stam <mstam at ripe.net>
> Date: Wednesday, 8 February 2023 at 10:13
> To: roberto.lucignani at caleidos.it <roberto.lucignani at caleidos.it>
> Subject: Re: [atlas] Measurement question
> Hello Roberto,
>  Would you be able to share screenshots/measurement ids so we can have a look?
>  Regards,
>  Michel
> 
> 
> On 8 Feb 2023, at 09:04, roberto.lucignani at caleidos.it wrote:
>  I’m doing some measurement from one of my software probes, the measure is a traceroute to a destination.
>  The results I get are completely different from what I see doing the same traceroute directly on host where the probe is installed. I configured the measure to sue the DNS resolution on the probe..
>  From the Atlas portal I get a traceroute with 7 hops, doing it directly on the host returns 28 hops, for the same destination.
>  Why this difference ?
>   Regards,
> Roberto
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