Solarwinds NPM snmp polling works somewhat

[RANT]

I have Solarwinds NPM monitoring a pair of MX105 firewalls (used as inline vpn concentrators). The status of the firewalls is down, but it's able to poll the interface traffic usage. Other remote end VPN MX firewalls don't have this issue, their status is UP.

[Inderdeep]

What exactly is the issue 

https://documentation.meraki.com/General_Administration/Monitoring_and_Reporting/SNMP_Overview_and_C...

[michalc]

Hi There,

The MX105 shouldn’t just flip to "Down" out of the blue. Have it been working before? Have there been any recent changes—like a firmware update on the MX105 pair in the last week or so? Maybe something sneaky like a network tweak or a config change that could’ve thrown things off? Also, how’s the reachability looking? Can the polling engine ping the MX105, or is something like a firewall rule or routing hiccup getting in the way?

Here’s where I’d start with:

• Check the polling method: Head over to the node details in NPM, click "Edit Node," and see if it’s set to "Most Devices: SNMP and ICMP." If ICMP’s blocked or timing out, that could explain the "Down" status, even if SNMP is happily pulling traffic data.
• Run a quick test: Try a manual ping from the NPM server to the MX105 IPs. If that fails, maybe the inline setup is causing ICMP to drop somewhere along the path.
• Grab a PCAP: If you’ve got access, run a packet capture from the NPM server toward the MX105. Are we seeing SNMP responses coming back? Any signs of ICMP replies (or lack thereof)?

[PhilipDAth]

How does it determine the status?  Via ping?  Can the machine ping the address you are monitoring?