[atlas] Magellan

Hi Ernst,

There is no way to know for absolute certain if a probe will be able to 
carry out a measurement and deliver results. There are a number of 
factors that prevent a measurement being scheduled on a probe (e.g. it 
is too busy, it is running an old firmware that doesn't support your 
measurement options). There are also factors that prevent it delivering 
results even if it is scheduled (e.g. it disconnects in the meanwhile, 
it has an issue with its hardware).

Many of these issues can be prevented most of the time by requiring one 
of the so-called stability tags when selecting your probes. These are 
tags which mark a probe as recently performing mostly successful 
measurements e.g. for an IPv4 measurement you could do:

$ ripe-atlas probe-search --asnv4 15435 --status 1 --format csv --field 
id --limit 50 --no-header --tag system-ipv4-stable-1d

to get a list of probes that have generally had good success with IPv4 
measurements in the last day.

In the case you gave, probe 2565 would have been excluded from this list 
because it has not generally been delivering results for a long while, 
which you can see here: https://atlas.ripe.net/probes/2565/#tab-builtins

For more info on the various probe tags you can look at the docs here: 
https://atlas.ripe.net/docs/getting-started/probe-tags.html#system-tags

I hope this helped, please let me know if you have any more questions.

Regards,
Chris

On 25/06/2023 17:14, Ernst J. Oud wrote:

> Perhaps someone can help me.
> 
> I use Magellan to create a measurement using connected probes on AS15435.
> 
> First I search for probes using Magellan and then I supply the ID’s returned of those probes reported as “connected” when creating the measurement.
> 
> I don’t want to wait for the stream to time-out so I use the “stream-limit” parameter, equal to the number of supplied connected probes. So when that number of connected probes have supplied data the streaming is complete.
> 
> However, it appears that probes are reported as connected by Magellan but do not supply data when specified for a measurement, for instance probe 2565. That probe is Reported by Magellan as connected but when I use it in a measurement it does not supply data. Thus streaming will only time-out and does not stop not when spevified connected probes have supplied data. Apparantly “connected” does not imply “can be used in a measurement”.
> 
> How can I supply probe ID’s in a “create measurement” command using Magellan knowing for sure that these probes will supply data?
> 
> Regards,
> 
> Ernst J. Oud