Table of Contents

Troubleshooting Poller and Monitoring Issues

Jennifer Trower Updated by Jennifer Trower

Read Time: 4 mins

Poller issues are usually one of three things: a Sonar-side configuration problem with the Monitoring Template or device credentials, a network issue on your side such as SNMP being unreachable, or a Sonar infrastructure issue such as missing data across many devices.

This article helps you match the issue you are seeing to the most likely cause and identify the right next step.

Permissions

Before getting started with troubleshooting, your user roles will need to be adjusted to account for the permissions required to view and diagnose Poller and Monitoring issues.

If you're a Super Admin, you already have full access, and no changes are needed. To learn more, see the Roles and Permissions article.
Entity Permission Why It's Required
Poller View all pollers Confirm Poller status and review which devices are attached.
Network Monitoring Template View all network monitoring templates Confirm the device has the correct Monitoring Template assigned.
Inventory View all inventory Open the device's inventory record to confirm its assigned template.
Misc View data usage and device statistics Confirm whether data is flowing for the device after a fix is applied.
SNMP Override View all SNMP overrides Verify whether SNMP overrides are configured for the device.

Troubleshooting Steps

Is It Poller or Netflow?

Before troubleshooting, confirm which subsystem the issue is in. The Poller and Netflow are separate systems, and a Poller fix will not resolve a Netflow issue.

  • Poller collects SNMP and ICMP data from your devices for monitoring, including uptime, interface stats, and alarms. If a device shows no SNMP or ICMP history, it is a Poller issue.
  • Netflow collects flow data for traffic analysis. If traffic data is missing but device status and interface stats are present, it is a Netflow issue.

The rest of this article covers Poller troubleshooting.

Symptom-to-Cause Quick Reference

Symptom Most Likely Cause Go To
No SNMP or ICMP history for a device Monitoring Template or device credentials Step 1
SNMP walk works but no data in Sonar Template config or credentials in Poller web UI Step 2
Data is missing for a date range across many devices Sonar infrastructure issue Step 3
Data appeared after a fix but user says it's still missing Browser cache or refresh Step 4

Step 1: Verify SNMP Reachability from the Poller

Use this step when a device shows no ICMP or SNMP history in Sonar.

The fastest diagnostic is to confirm whether SNMP works from the Poller itself, independent of Sonar.

To troubleshoot:

  1. Connect to the Poller and run an SNMP bulk walk against the target device using the credentials configured in the Poller.
  2. If the walk fails, the issue is on your network or device side. Check device ACLs, SNMP community strings, firewall rules between the Poller and the device, and device CPU load.
  3. If the walk succeeds but Sonar shows no history, the issue is in Sonar's Monitoring Template configuration or in the device credentials stored in the Poller web UI. Continue to Step 2.
Step 2: Verify Monitoring Template and Device Credentials

Use this step when the SNMP bulk walk succeeds from the Poller, but the device shows no history in Sonar.

To troubleshoot:

  1. In Sonar, navigate to the device's inventory record.
  2. Confirm the device has the correct Monitoring Template assigned. Templates control which OIDs are polled and what data is stored.
  3. Open the Poller web UI.
  4. Confirm the device's credentials are entered correctly. Missing or incorrect credentials in the Poller web UI is a common cause when the Poller can reach the device manually but is not collecting data.
  5. Wait five minutes, then refresh the device view in Sonar to confirm data is flowing.

For more information on providing credentials, see Pollers: General Overview, Deployment Strategy, Build Out & Setup.

Step 3: Data Is Missing for a Date Range Across Many Devices

Use this step when multiple devices show a gap in their monitoring data for a specific date range and SNMP and credentials are correct.

This pattern usually indicates a Sonar infrastructure issue rather than a configuration problem on your side. One common cause is a blob storage configuration issue, where data is received by Sonar's web layer but cannot be written to storage, resulting in silent data loss.

To troubleshoot:

  1. Confirm the date range when data is missing.
  2. Confirm the issue affects multiple devices.
  3. Open a support ticket and include the date range, the affected devices or device groups, and confirmation that SNMP from the Poller still works for those devices.

Data lost during this kind of infrastructure issue cannot generally be recovered.

Step 4: Data Still Appears Missing After a Fix

Use this step when Support or your team has applied a fix, but the data still appears to be missing in the dashboard.

In most cases, the data is flowing, but the dashboard view has not refreshed since the fix was applied.

To troubleshoot:

  1. Confirm fresh data is appearing in Sonar from your perspective.
  2. Refresh the browser or close and reopen the dashboard.
  3. If data is still not appearing after a hard refresh and five minutes have passed since the fix, treat it as a new issue.

When to Open a Support Ticket

Open a support ticket after completing the relevant troubleshooting step if the issue continues.

Include the following information:

  1. The symptom you are seeing.
  2. The step in this article you completed.
  3. Device IDs or inventory item IDs affected.
  4. Date range when the issue began.
  5. Result of the SNMP bulk walk from the Poller.
  6. Whether the Monitoring Template and device credentials have been verified.
  7. Whether the issue impacts one device, a subset, or all devices.
  8. Whether this appears to be Poller or Netflow data.

How did we do?

Pollers: General Overview, Deployment Strategy, Build Out & Setup

Contact