SNMP issues

SNMP is the most commonly used method to monitor the health of NetScaler and the services configured on it. It involves polling specific strings, called OIDs (Object Identifiers), that represent various NetScaler properties such as interface stats, or NetScaler entities such as vServers and services, using external tools to monitor health and performance characteristics.

The NetScaler eDocs cover how to set SNMP using the various versions (SNMP v1, v2, v3), but at a basic level, you need the following configuration:

  • An external SNMP manager, or your own PC if you use an SNMP browser.
  • The SNMP MIB (Management Information Base), which contains, in a tree-like structure, all the properties of NetScaler and its objects that you can poll, and what their OIDs are. These are located in the /netscaler/snmp/ folder. You can also download the MIB files from the GUI:
    SNMP issues
  • SNMP community configuration, which needs to match what is configured on the server side.
  • Adding the SNMP Manager on the NetScaler

Troubleshooting SNMP on a NetScaler

Most issues in this area come down to one of three areas, as follows:

  • Reachability issues: Take a trace to verify that the SNMP requests are getting through to the NetScaler. For example, are ports UDP 161 and 162 open? Also, ensure that access to and from the NSIP is allowed through the firewall, or use an appropriate netprofile.
  • Configuration issues: If you are seeing no response at all, check if the community string and versions match on both sides. Verify permissions such as GET, SET, and BULK. This is part of the community configuration. For example, add snmp community london_snmp_goup ALL. If you're using SNMP V3, also ensure that authentication is set up correctly. Ensure you are polling the correct OID. You can browse through the MIBs for this purpose, or alternatively use the file mib.txt, which handily lists in all system-level OIDs.

    Note

    To browse through the MIB, you could also use a tool (my favorite is MIB browser, by iReasoning) to click around and discover all the available OIDs. Another excellent alternative for quick testing is snmpwalk.

  • SNMP Manager missing in the list: If there are SNMP Managers configured on NetScaler, ensure that your SNMP Manager is in that list, otherwise the requests may fail. You can use the command show snmp manager for this purpose. This a common configuration issue when working with Command Center discovery of NetScaler.
..................Content has been hidden....................

You can't read the all page of ebook, please click here login for view all page.
Reset