Troubleshooting network device scan failures

When you observe failures while scanning network devices, use the troubleshooting steps described in this section to either resolve the problem or create a BMC Support case.

Issue symptom

• An SNMP scan fails.

Issue scope

In the DiscoveryAccess node, any of the following error messages are displayed:

• UnsupportedDevice
• NoAccess
• Error
• ERROR: SNMP++: SNMP request timeout

Resolution

Perform the following steps to troubleshoot the SNMP scan failures:

Step 1: Verify the prerequisites

1. Check that the scanned device is supported. 
   Get the sysoid (sometimes, this is in the result of getDeviceInfo) and check that it is in the list of supported SNMP devices. If it is not yet supported, contact BMC Customer Support. If possible, also provide a device capture to Support.
2. Check that the scanned device can be pinged (ping device_ip_address) from the appliance/instance or the BMC Discovery Outpost scanning it. If this does not work, engage your IT to check why the IP does not respond. 

3. Check that the SNMP port of the scanned device, typically port 161, is opened from the appliance/instance or the BMC Discovery Outpost scanning it. If not, contact your IT team to open the port.
   You can use the following commands to check for open port:

   nmap -p 161 device_ip_address

   The typical result when the port is open:

   [tideway@discovery ~]$ nmap -p 161 device_ip_address
PORT STATE SERVICE
161/tcp open unknown



   telnet device_ip_address 161

   The typical result when the port is closed:

   [tideway@discovery ~]$ telnet device_ip_address 161
telnet: connect to address device_ip_address: Connection refused



4. Check your SNMP credential with a test credential from the BMC Discovery UI. If this fails, try again with snmpwalk. If this too fails, send the snmpwalk commands and results to your IT team and ask why it fails. See the following examples for SNMP version-dependent information:

   1. SNMP v1:

      /usr/tideway/snmp++/bin/snmpWalk device_ip_address -v1 -Cpublic

   2. SNMP V2c:

      /usr/tideway/snmp++/bin/snmpWalk device_ip_address -v2c -Cpublic

   3. SNMP V3:

      /usr/tideway/snmp++/bin/snmpWalk device_ip_address '1.3.6.1.2.1.17.4.3.1' -v3 -snMyLogin -sl2 -authMD5 -uaMyPassword

      /usr/tideway/snmp++/bin/snmpWalk device_ip_address '1.3.6.1.2.1.17.4.3.1' -v3 -snMyLogin -sl3 -authSHA -ua'My$Password' -privDES -up'MyPrivateKey'

      If all the prerequisites are working correctly but the scan still fails, proceed to Step 2.

Step 2: Test and review the BMC Discovery configuration

In case of a time out, perform the following steps:

1. Move the dedicated credential for this IP address to the top of the credential list.
2. Disable getBulk in the SNMP credential.
3. Set the credential timeout value to 300.
4. Restart the tideway services.

If the problem persists, send the discovery debug logs and the result of the earlier steps to BMC Customer Support.