Introduction to SNMP and MIB

Simple Network Management Protocol(SNMP) is a UDP-based network protocol used mostly in network management systems to monitor network-attached devices. SNMP is a component of the Internet Protocol Suite as defined by the Internet Engineering Task Force(IETF) and consists of a set of standards for network management, including an application layer protocol, a database schema and a set of data objects.

SNMP exposes management data in the form of variables on the managed systems that describe the system configuration. These variables can be queried using SNMP management applications.

SNMP allows a Network Management Station to do the following:

  • Poll a device for info or to trend data i.e. VOSS Automate server load graph via HOST-SYSTEMS-MIB

  • Receive notifications in the form of traps or informs in response to events, threshold violations, whatever the trap definitions in the loaded MIBs are. We enable process monitoring and disk space checks - when triggered, these send out a trap.

A management information base (MIB) is a form of virtual database used for managing the entities in a communications network. Working closely with SNMP, the hierarchical data structure describes all of the objects that a device can report the status of.

The MIB is structured based on the RFC 1155 standard. This standard defines how the MIB information is organized, what data types are allowed and how resources within the MIB are named. Each MIB contains the name, object identifier (a numeral), data type and the permissions relating to whether the value can be read or written to. The top hierarchies of the MIB are fixed; however, certain sub trees can be defined by product vendors and other organizations.

The variables within MIB are named using the Abstract Syntax Notation 1 (ASN.1). This is an international standard for representing data.

SNMP Terminology:

  • MIB: The term MIB is used to refer to the complete collection of management information available on an entity, while MIB subsets are referred to as MIB-modules.

  • NMS: ANetwork Management System is a combination of hardware and software used to monitor and administer a network and the devices associated with that network.

SNMP on VOSS Automate Platform is configured after initial system setup. The following SNMP parameters can be configured. Refer to SNMP Configuration and Queries and the index for commands.

  • The SNMP system name

    Identifies the system being monitored on the NMS (Network Management System). Defaults to nodename.domainname.

  • The SNMP system location

    Describes the location of the system. Defaults to Unknown.

  • The SNMP system contact

    Defines the email address of administrator responsible for the system. Defaults to None.

  • The SNMP query source

    URI from which the system accepts SNMP queries. Formatted as snmp://community@host[:port] for version 2 and snmp://user:auth:password@host[:port] for version 3

    CIDR-style IP (e.g. 196.0.0.0/8) network allowed to query SNMP from this host. This is used to limit the hosts allowed to manage the system via SNMP. Defaults to all hosts.

  • The SNMP load triggers

    The 1, 5 and 15 minute load averages that will trigger warnings via SNMP. Defaults to values dynamically calculated from the number of CPUs in the system. This should be formatted as 8n/4n/2n (where n represents the number of processors available) when entered into the configuration wizard during setup.

  • The SNMP trap destination

    Formatting identical to query source.

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SNMP Configuration and Queries

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SNMP Traps