# SNMP

SNMP is an application layer protocol that facilitates exchange of management information between network devices. SNMP is defined in RFC 1157.

The SNMP manager or agent collects the properties of the managed object within the managed device from the MIB. The latest Internet MIB is given in RFC 1213, also known as MIB-II.

Currently, there are three versions of SNMP: SNMPv1 (basic version), SNMPv2 (provides additional protocol operations), and SNMPv3 (provides new security model).

Storage systems support the SNMPv1 compatible agent. This agent supports both MIB-II and the NetApp custom MIB. The storage system has an extensive MIB, which is included in the doc/mib directory of the Data ONTAP distribution. The latest versions of the Data ONTAP MIB files are available online on the NOW NetApp on the Web site.

The MIB is an ASCII document that describes each variable, such as sysDescr, and assigns it an Object Identifier (OID). To use SNMP, you must know the OID of the required variable. The MIB document format is, by design, readable by both machines and humans. The MIB format, however, does not make it easy to determine the OID of a given variable, because it is specified in terms of a parent variable. For this reason, a file called traps.dat is included in the doc/mib directory. This file lists each of the SNMP variables supported by Data ONTAP and the complete OID required to access it. This file, originally intended for users of the SNMP traps command, adds the prefix snmp to each OID, which you should ignore when using snmpget or snmpwalk.

Any new feature of the NetApp storage systems is documented and reported through SNMP in the major releases in which they are introduced. Therefore, the MIB is always growing. NetApp reports as much as possible about an appliance through the MIB.

The SNMP protocol specifies GET, SET, and TRAP operations. For security reasons, NetApp products do not support SET operations.

### SNMP OID

The OID space is tree structured. An OID such as .iso.org.dod.internet.mgmt.mib2.system.sysDescr.0 (which translates to .1.3.6.1.2.1.1.1.0) can be read as you read a file system path. The sysDescr variable resides within the system space, which is contained in the mib2 space, which in turn is contained within mgmt, and so on. If the last number of the OID is a zero, it means a single value is requested. Integers above zero are requests for individual elements in tables. The snmpwalk command (a standard UNIX based application) is useful to learn about OIDs and how they relate to query output and the entries for them in the MIB. An snmpwalk of .1.3.6.1.2, for example, returns a lot of information about the system’s TCP/IP state. An snmpwalk of 1.3.6.1.4.1.789.1 returns all the entries in the NetApp MIB.

| The SNMP MIB files are present are on the NOW site. Click here to view.

Related Topics

- Version Matrix