Dealing with the “OID not increasing” error

  1. I’m walking a particular Agent with the nextCmd() or bulkCmd() functions. It works for some OIDs, but invariably fails at certain OID with the OID not increasing error. What does it mean and how do I fix that?

  1. The Agent you are talking to seems to be broken. The OID not increasing message means that in the course of fetching OIDs from the Agent, Manager receives an OID that is not greater than those passed in request. Due to the nature of GETNEXT/GETBULK algorithm, passing the same or lesser OID to Manager would result in fetching the same set of OIDs over and over again effectively creating an infinite loop between Manager and Agent so they may never reach the end of MIB. To prevent this the Manager tries to intervene and prevent such loop from happening.

    If you have to work with a broken Agent and can terminate the GETNEXT/GETBULK command at some point, you can pass the ignoreNonIncreasingOid=True keyword parameter to the nextCmd() or bulkCmd() to disable OID verification at the Manager side.

for (errorIndication,
     errorStatus,
     errorIndex,
     varBinds) in nextCmd(SnmpEngine(),
                          CommunityData('public'),
                          UdpTransportTarget(('demo.snmplabs.com', 161)),
                          ContextData(),
                          ObjectType(ObjectIdentity('1.3.6')),
                          ignoreNonIncreasingOid=True):

    if errorIndication:
        print(errorIndication)
        break
    elif errorStatus:
        print('%s at %s' % (errorStatus.prettyPrint(),
                            errorIndex and varBinds[int(errorIndex) - 1][0] or '?'))
        break
    else:
        for varBind in varBinds:
            print(' = '.join([x.prettyPrint() for x in varBind])