# Evaluating NOTIFICATION-TYPE

SNMP SMI defines notifications as a TRAP or INFORM PDU containing the indication of type (snmpTrapOID) and a set of MIB variables (Managed Objects Instances) fetched from Agent’s MIB at the moment of notification.

Consequently, sending specific NOTIFICATION-TYPE implies including certain set of OIDs into PDU. PySNMP offers this facility through NotificationType class.

## Sending notification with OBJECT’s

Send SNMP TRAP notification using the following options:

- SNMPv2c

- with community name ‘public’

- over IPv4/UDP

- send TRAP notification

- to a Manager at 104.236.166.95:162

- with TRAP ID IF-MIB::ifLink as MIB symbol

The IF-MIB::ifLink NOTIFICATION-TYPE implies including four other var-binds into the notification message describing the incident occurred. These var-binds are: IF-MIB::ifIndex.”x” IF-MIB::ifAdminStatus.”x” IF-MIB::ifOperStatus.”x” IF-MIB::ifDescr.”x”

Where “x” is MIB table index (instance index).

Functionally similar to:

$ snmptrap -v2c -c public 104.236.166.95 0 1.3.6.1.6.3.1.1.5.3 IF-MIB::ifIndex.”1” IF-MIB::ifAdminStatus.”1” IF-MIB::ifOperStatus.”1” IF-MIB::ifDescr.”1”

    from pysnmp.entity import engine, config
    from pysnmp.carrier.asyncore.dgram import udp
    from pysnmp.entity.rfc3413 import ntforg
    from pysnmp.smi import rfc1902, view

    #
    # Here we fill in some values for Managed Objects Instances (invoked
    # later while building TRAP message) by NOTIFICATION-TYPE macro evaluation.
    # In real Agent app, these values should already be initialized during
    # Agent runtime.
    #
    instanceIndex = (1,)
    objects = {
        ('IF-MIB', 'ifIndex'): instanceIndex[0],
        ('IF-MIB', 'ifAdminStatus'): 'up',
        ('IF-MIB', 'ifOperStatus'): 'down',
        ('IF-MIB', 'ifDescr'): 'eth0'
    }

    # Create SNMP engine instance
    snmpEngine = engine.SnmpEngine()

    # MIB view controller is used for MIB lookup purposes
    mibViewController = view.MibViewController(snmpEngine.getMibBuilder())

    # SecurityName <-> CommunityName mapping
    config.addV1System(snmpEngine, 'my-area', 'public', transportTag='all-my-managers')

    # Specify security settings per SecurityName (SNMPv2c -> 1)
    config.addTargetParams(snmpEngine, 'my-creds', 'my-area', 'noAuthNoPriv', 1)

    # Setup transport endpoints and bind it with security settings yielding
    # a target name:

    # UDP/IPv4
    config.addTransport(
        snmpEngine,
        udp.domainName,
        udp.UdpSocketTransport().openClientMode()
    )
    config.addTargetAddr(
        snmpEngine, 'my-nms-1',
        udp.domainName, ('104.236.166.95', 162),
        'my-creds',
        tagList='all-my-managers'
    )

    # Specify what kind of notification should be sent (TRAP or INFORM),
    # to what targets (chosen by tag) and what filter should apply to
    # the set of targets (selected by tag)
    config.addNotificationTarget(
        snmpEngine, 'my-notification', 'my-filter', 'all-my-managers', 'trap'
    )

    # Allow NOTIFY access to Agent's MIB by this SNMP model (2), securityLevel
    # and SecurityName
    config.addContext(snmpEngine, '')
    config.addVacmUser(snmpEngine, 2, 'my-area', 'noAuthNoPriv', (), (), (1, 3, 6))

    # *** SNMP engine configuration is complete by this line ***

    # Create Notification Originator App instance.
    ntfOrg = ntforg.NotificationOriginator()

    # Build and submit notification message to dispatcher
    ntfOrg.sendVarBinds(
        snmpEngine,
        'my-notification',  # notification targets
        None, '',  # contextEngineId, contextName
        rfc1902.NotificationType(
            rfc1902.ObjectIdentity('IF-MIB', 'linkUp'),
            instanceIndex=instanceIndex,
            objects=objects
        ).resolveWithMib(mibViewController)
    )

    print('Notification is scheduled to be sent')

    # Run I/O dispatcher which would send pending message and process response
    snmpEngine.transportDispatcher.runDispatcher()

`Download` script.

See also: library reference.