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Troubleshoot SNMP on VOS Devices

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This article describes how to troubleshoot Simple Network Management Protocol (SNMP) issues on Versa Operating SystemTM (VOSTM) devices. 

SNMP operations include both polling and trap generation, which have different configuration requirements. The SNMP troubleshooting scenarios below are divided into polling-related and trap related issues. 

The primary sources of SNMP troubleshooting information on VOS devices are the key log files:

  • devel.log
  • snmp.log

Both log files are in the /var/log/versa/confd directory.

Troubleshoot SNMP Polling

You can use the following procedures to troubleshoot issues related to SNMP polling.

Verify Connectivity and Systemwide Issues

To verify that polling requests from a remote client can reach an SNMP server on a VOS device, do the following:

  1. To verify that the VOS device is receiving SNMP polling requests from an SNMP manager, issue the grep request /var/log/versa/confd/snmp.log command.

    For example, the following SNMP log file entry displays that the VOS device receives polling requests from the remote client. If there is no polling request entry in the SNMP log file, that means that either the VOS device is not receiving the SNMP requests, or SNMP logging is not enabled.
grep request /var/log/versa/confd/snmp.log
<INFO> <DATE/TIME> <DEVICE_NAME> confd[1843]: snmp get-*request reqid=XYZ 
<SNMP_CLIENT_IP>:<SNMP_CLIENT_PORT> (<REQUESTED_OID_NAME>)
  1. To verify the SNMP agent is enabled on a VOS device with the correct SNMP version (V2C or V3)and UDP port (161):
    1. In Director view, select the Administration tab in the top menu bar.
    2. Select an appliance from the main panel. The view changes to Appliance view. 
    3. Select the Configuration tab in the top menu bar.
    4. Select Objects & Connectors > Connectors > SNMP > Agent in the left menu bar. The SNMP Agent pane displays the information. For more information, see Configure SNMP.

      connectors-snmp-agent.png

Note: Requests with the incorrect SNMP version may trigger error messages in the devel.log file with the reason snmpInASNParseErrs.

  1. To verify the VNF manager settings on the VOS device:
    •  In Director view, select the Administration tab in the top menu bar.
    • Select an appliance from the main panel. The view changes to Appliance view. 
    • Select the Configuration tab in the top menu bar.
    • Select Others > System > Configuration > Configuration in the left menu bar. The VNF Manager pane displays the information.

      others-system-config-vnf-manager.png
  • Add the remote SNMP client IP address and the local VOS interface to the VNF manager list only when polling a VOS-owned interface such as VNI, aggregated Ethernet, or TVI interface, and there is no split tunnel between the corresponding VOS virtual router and the global router (Host Linux OS). 
  • Do not add the remote SNMP client IP address to the VNF manager list, either individually or as part of an IP address range, when polling the VOS management interface (eth0) or when a split tunnel exists between the VOS virtual router and the global router (Host Linux OS) that permits SNMP traffic to reach the host operating system.
  1. To verify that the VOS device is sending SNMP responses to the SNMP client, issue the grep response /var/log/versa/confd/snmp.log command.

    For example, the following SNMP log file entry displays that the VOS device sends responses along with the value returned for the requested OID.  
    grep response /var/log/versa/confd/snmp.log
<INFO> <DATE/TIME> <DEVICE_NAME> confd[1843]: snmp get-response reqid=XYZ 
<SNMP_CLIENT_IP>:<SNMP_CLIENT_PORT> (<REQUESTED_OID_NAME>=<VALUE>)
    If the SNMP log file has valid response entries, but the remote SNMP client does not receive the response, verify the connectivity and forward rules from VOS device to the remote SNMP client.

Verify SNMP Protocol-Specific Issues

You can check the devel.log file when the snmp.log file shows no response to the queries sent or contains logs with error responses. 

To check real time messages in the devel.log file while running the queries from the remote SNMP client, issue the following command:

  •  tail -f /var/log/versa/confd/devel.log

The following sections describe the diagnostic information in the command output regarding the SNMP query failures. 

Incorrect Community Value in SNMPv2c Queries

Symptom: The devel.log file output displays the PDU discarded: bad community name error.

<INFO> <DATE/TIME> <DEVICE_NAME>  confd[1843]: devel-snmpa PDU discarded: bad community name: 
<SNMP_CLIENT_IP> <SNMP_COMMUNITY_NAME>

Solution: Verify that the SNMP community value in the VOS device configuration and in the SNMP query are the same.

To check the SNMP community value:

  1. In Director view, select the Administration tab in the top menu bar.
  2. Select an appliance from the main panel. The view changes to Appliance view. 
  3. Select the Configuration tab in the top menu bar.
  4. Select Objects & Connectors > Connectors > SNMP > Communities in the left menu bar. The main pane displays the information.

    connectors-snmp-communities.png

SNMPv3 User Does Not Exist

Symptom: The devel.log file output displays the usmStatsUnknownUserNames error.

<INFO> <DATE/TIME> <DEVICE_NAME>  confd[1843]: 
devel-snmpa sending report for reason: {securityError,usmStatsUnknownUserNames}

Solution: Verify that the SNMPv3 user is configured in the SNMP > USM configuration.

To check the SNMPv3 user in the USM configuration:

  1. In Director view, select the Administration tab in the top menu bar.
  2. Select an appliance from the main panel. The view changes to Appliance view. 
  3. Select the Configuration tab in the top menu bar.
  4. Select Objects & Connectors > Connectors > SNMP > USM in the left menu bar. The main pane displays the information.

    connectors-snmp-usm-local.png

Invalid SNMPv3 Encryption Password or Algorithm

Symptom: The devel.log file output displays the usmStatsDecryptionErrors error.

<INFO> <DATE/TIME> <DEVICE_NAME>  confd[1843]: 
devel-snmpa sending report for reason: {securityError,usmStatsDecryptionErrors}

Solution: Verify that the SNMPv3 user privacy configuration matches with the parameters in the SNMP request.

To check the SNMPv3 user privacy configuration:

  1. In Director view, select the Administration tab in the top menu bar.
  2. Select an appliance from the main panel. The view changes to Appliance view. 
  3. Select the Configuration tab in the top menu bar.
  4. Select Objects & Connectors > Connectors > SNMP > USM in the left menu bar.
  5. Select the Local tab, and then select an SNMPv3 user name. The Edit Local User screen displays the privacy configuration.

    connectors-snmp-usm-edit-local-user.png

Invalid SNMPv3 Authentication (Password or Digest Algorithm)

Symptom: The devel.log file output displays the usmStatsWrongDigests error.

<INFO> <DATE/TIME> <DEVICE_NAME>  confd[1843]: 
devel-snmpa sending report for reason: {securityError,usmStatsWrongDigests}

Solution: Verify that the SNMPv3 user authentication configuration matches with the parameters in the SNMP request.

To check the SNMPv3 user authentication configuration:

  1. In Director view, select the Administration tab in the top menu bar.
  2. Select an appliance from the main panel. The view changes to Appliance view. 
  3. Select the Configuration tab in the top menu bar.
  4. Select Objects & Connectors > Connectors > SNMP > USM in the left menu bar.
  5. Select the Local tab, and then select an SNMPv3 user name. The Edit Local User screen displays the authentication information.

    connectors-snmp-usm-edit-local-user1.png

Troubleshoot SNMP Traps

You can use the following procedures to troubleshoot issues related to SNMP traps.

Verify the VOS Device Generates SNMP Traps

If the VOS device does not send SNMP traps when an alarm is triggered, check the SNMP log file for SNMP trap-related entries. To do this, issue the grep trap /var/log/versa/confd/snmp.log command. The command output displays the destination IP address and alarm type values if the traps are generated. If SNMP traps are not present in the SNMP log file, perform the following troubleshooting procedures.

Verify Alarm Statistics and Configuration

  1. To verify the VOS device alarm statistics, issue the show alarms statistics detail CLI command. In the command output:
    • If the sum of Num New Alarms and Num Cleared Alarms is zero or non-increasing for the selected alarm type, an alarm is not triggered on the device.
    • If the sum of Num New Alarms and Num Cleared Alarms is non-zero, but Num SNMP Alarms is zero for the selected alarm type, an alarm type does not have SNMP as a destination.
  2. To edit an alarm for all alarms or individual alarm type:
    1. In Director view, select the Administration tab in the top menu bar.
    2. Select an appliance from the main panel. The view changes to Appliance view. 
    3. Select the Configuration tab in the top menu bar.
    4. Select Others > Alarms in the left menu bar.
    5. Select the Alarms tab, and then select an alarm name/type. The Edit Alarm screen displays the information. For more information, see Configure VOS Device Alarms.

      Others-alarms-edit.png

Verify the SNMP Trap Profile

Check the SNMP trap destination host configuration in the SNMP trap profile to make sure that the parameters match the SNMP trap collector setup. 

To view the SNMP trap profile configuration:

  1. In Director view, select the Administration tab in the top menu bar.
  2. Select an appliance from the main panel. The view changes to Appliance view. 
  3. Select the Configuration tab in the top menu bar.
  4. Select Objects & Connectors > Connectors > SNMP > Trap Profiles in the left menu bar.
  5. In the main pane, click a profile name. The Edit Trap Profile screen displays the following information:
    • Target IP address and UDP port (default UDP port is 162)
    • SNMP version and security parameters (Community Name for SNMPv2c or Sec Level, and User for SNMPv3)

      connectors-snmp-trap-profiles-edit.png

Verify Reachability for SNMP Trap

If SNMP traps are not received on the SNMP trap collector even after VOS device generates SNMP traps to the expected destination:

  1. Verify the local source IP address for SNMP traps. This also defines which virtual router or global router is used to send SNMP traps.
    1. In Director view, select the Administration tab in the top menu bar.
    2. Select an appliance from the main panel. The view changes to Appliance view. 
    3. Select the Configuration tab in the top menu bar.
    4. Select Objects & Connectors > Connectors > SNMP > Agent in the left menu bar. The SNMP Target Source pane displays the information.

      connectors-snmp-agent-target-source.png
  2. Verify the VNF manager settings on the VOS device:
    •  In Director view, select the Administration tab in the top menu bar.
    • Select an appliance from the main panel. The view changes to Appliance view. 
    • Select the Configuration tab in the top menu bar.
    • Select Others > System > Configuration > Configuration in the left menu bar. The VNF Manager pane displays the information.

      others-system-config-vnf-manager.png
    • Add the remote SNMP trap collector IP address and the local VOS interface to the VNF manager list only when a VOS-owned interface such as VNI, aggregated Ethernet, or TVI interface is used to send SNMP traps. Also, there is no split tunnel between the corresponding VOS virtual router and the global router (Host Linux OS). 
    • Do not add the remote SNMP trap collector IP address to the VNF manager list, either individually or as part of an IP address range, when the VOS management interface (eth0) is used to send SNMP traps, or there is a split tunnel between the VOS virtual router and the global router (Host Linux OS) that permits SNMP traffic from the host operating system.
  3. Verify whether there is a valid path from the configured SNMP target source to the remote SNMP trap collector, and the UDP port configured for SNMP traps (default is 162) is allowed across the whole path. 

Supported Software Information

Releases 21.2 and later support all content described in this article.

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