As best I can determine the 2nd and 3rd hops are topologically very close to the major IX points in Seattle. Based on the geographic location of my probe and starlink terminal, its traffic goes up to space and back down again to 1 of 3 possible starlink earth stations in Washington state. These earth stations are known to be located at either the Starlink offices in Redmond, WA, there is one site colocated with a Level3/Centurylink/Lumen DWDM site slightly east of Seattle, and another which is at a commercial teleport in the north-central part of the state. RTT ICMP ping times to things in Seattle are a combination of two round trips through space, plus modem framing/encoding/FEC, and terrestrial latency from one of those earth stations to the downtown Seattle destination and back. For instance to the anycase instances of a nameserver that I know to be physically located at one of Seattle's main carrier hotels. On Fri, Apr 23, 2021 at 3:22 AM Ponikierski, Grzegorz via ripe-atlas < ripe-atlas@ripe.net> wrote:
Malte Appel already partially responded to you questions. I will try to provide more details.
Each probe has build-in measurements for 1st and 2nd hop. For your probe it is:
- nice view https://atlas.ripe.net/probes/1001821/#tab-builtins - 1st hop https://atlas.ripe.net/api/v2/measurements/1/results/?probe_ids=1001821&start=1619136000&stop=1619222399&format=json - 2nd hop https://atlas.ripe.net/api/v2/measurements/2/results/?probe_ids=1001821&start=1619136000&stop=1619222399&format=json
If you take your probe as an example you will notice that your first hop is your local router (Starlink dish?) and it has RTT <1ms. It's your 2nd hop which can indicate what RTT is generated by Starlink satellite connection (RTT Median Average ~30ms). I'm curious where exactly is located this 2nd hop :)
Regards,
Grzegorz
*From: *Ray Bellis <ray@isc.org> *Date: *Friday 2021-04-23 at 10:44 *To: *"ripe-atlas@ripe.net" <ripe-atlas@ripe.net> *Subject: *Re: [atlas] Satellite based "last mile" and Atlas probes
On 22/04/2021 20:52, Ponikierski, Grzegorz via ripe-atlas wrote:
Checking
first hop can be tricky because this first hop can be local router with
RTT <1ms and second hop can indicate that we are on satellite
connectivity. For that API for sure API must be used. Here is the full
list of build in measurements:
https://urldefense.com/v3/__https://beta-docs.atlas.ripe.net/built-in/refere... <https://urldefense.com/v3/__https:/beta-docs.atlas.ripe.net/built-in/reference.html*traceroute-5-000-6-999__;Iw!!GjvTz_vk!CGnJSJwFwnAeSTFJcu_wN5qF5pxMnHYnUY2rcHz_afOJoH0Tp49DDDQm0TvPlSQ$>
< https://urldefense.com/v3/__https://beta-docs.atlas.ripe.net/built-in/refere... <https://urldefense.com/v3/__https:/beta-docs.atlas.ripe.net/built-in/reference.html*traceroute-5-000-6-999__;Iw!!GjvTz_vk!CGnJSJwFwnAeSTFJcu_wN5qF5pxMnHYnUY2rcHz_afOJoH0Tp49DDDQm0TvPlSQ$>
+ build in ping tests for 1^st and 2^nd hop are respectively measurement
#1 and #2.
Can you please elaborate on this?
I have a separate need (relating to an ICANN RSSAC WG) to be able to
detect high latency last mile hops but I could not identify the specific
"built-in ping tests for 1st and 2nd hop" that you described.
Were you perhaps suggesting that it was actually just the first couple
of rows of data from the built-in *traceroute* tests that hold this data?
thanks,
Ray