[Xymon] Monitored router shown as flapping

J.C. Cleaver cleaver at terabithia.org
Thu Nov 19 03:03:20 CET 2015

On Wed, November 18, 2015 5:37 pm, Colin Coe wrote:
> Hi all
> I have a Cisco router at a remote location which we connect to via its
> HSPA+ (3G/mobile data) network interface.
> Xymon shows this router (and the kit behind it) as flapping.  I've set
> a ping going from the Xymon server to this router and left it going
> for approx 20 minutes.  In this time Xymon showed it being
> "unreachable" however no pings were lost from the CLI.
> We have many routers with this setup and these other routers are not
> experiencing this problem.
> The server is running RHEL 6 + Xymon 4.3.23 RPM from Terabithia.
> Any ideas on this?
> Thanks
> CC

If it's flapping rather than solid down, it might be that you have two
different systems reporting in under the same hostname. Any chance this is
listed in more than one place? If not that, perhaps DNS flakiness? Try
using testip if you know it has a static one.

If you're not getting any packet loss over 20m from a steady ping, then
it's almost certain a config issue somewhere. Or some *very* unlucky ICMP


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