Monitored router shown as flapping
list Colin Coe
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
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attachment.pnglist Japheth Cleaver
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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
packets...
HTH,
-jc
list Colin Coe
Hi JC Many thanks for the pointers. Turned out be two separate problems. One of the Xymon servers was misconfigured and the VPN tunnel it uses didn't define the router's subnet (the site is new). Thanks again CC
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On Thu, Nov 19, 2015 at 10:03 AM, J.C. Cleaver <user-87556346d4af@xymon.invalid> wrote: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 CCIf 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 packets... HTH, -jc