[Xymon] little explanation of conn test.

[John Thurston]

On 1/25/2016 12:13 PM, Randall Badilla Castro wrote:
> Hi guys:
> We are getting this graph from a webserver and the boos want a deeper
> explanation of it.

There isn't much to explain. As you have figured out, the "conn" test is 
an ICMP ECHO. The time plotted on this chart is how long it took for the 
ECHO request/response to make the round-trip. The end-points of the 
round trip are imprecise. On some systems, the hardware on the NIC will 
respond to an ECHO request. In other cases, the driver between the NIC 
and OS will respond. In other cases, the response may come from the 
operating system. Also hidden from this chart is the path the 
request/return traveled across the network.

The bumps on your chart, by themselves, mean nothing. "Something" made 
these two round trips take longer than usual. You have no way to know 
what or where.

The "conn" chart is valuable for only a couple of things:
   Is the host's NIC kinda-sorta alive?
   Is there a pattern of latency or loss?

Trying to extract more information from the "conn" test or chart is a 
fool's errand.
-- 
    Do things because you should, not just because you can.

John Thurston    907-465-8591
John.Thurston at alaska.gov
Enterprise Technology Services
Department of Administration
State of Alaska