[atlas] Algortithm for probe detecting its offline

On 12/20/11 20:20 , Greg B - NANOG wrote:
> I wanted to ask what is the algorithm / methodology used for a probe 
> detecting / reporting it is offline?
>
> I ask, because this morning I intentionally rebooted my cable modem on 
> the network the probe is attached to, which brought my internet down 
> for about 1-2 minutes (I was using the internet immediately after the 
> cable modem re-synched), but the probe is reporting that outage as a 
> 29 minute outage rather than a few minutes.
>
> Any comments on why there should be such a large variance from my 
> actual experience versus what the probe saw?
>
At the moment, we use a rather simplistic method and that is the 
connection to the controller. That connection is often re-established 
within 3 minutes, but it may also take much longer.

Note that the probe continues doing measurements while the connection to 
the connection to the controller is down, so when it is back up it is 
possible to verify what happened exactly.

We are trying to figure out where that delay is coming from, but at the 
moment we don't have the answer yet.