In addition to the five core fields of a discovery filter, you can specify additional information for a filter to control the polling of any system that matches an IP address of the filter. The additional fields, which are referred to as extended options, are identified in Discovery filter that contains extended options.

Table 1. Discovery filter that contains extended options

Discovery filter fields

Discovery filter example

1  SNMPv3 is not currently supported for autodiscovery.

Core fields

IP Address Range

*.*.*.*

System Name

*

System Description

*

SystemOID

*

System Types

Router

Extended option fields

SNMP Port

165

SNMP Version 1

AUTODETECT

Access Mode

ICMPSNMP

Community String

public1

When a candidate system’s IP address matches an IP address of an extended discovery filter, the IP Manager uses the candidate system’s IP address and the values of the following user-specified extended options of the filter to poll the candidate system:

  • SNMP Port

    Enables you to specify an alternate port on which systems receive SNMP requests. The default value is 0, which indicates that the IP Manager uses the port number value (161) of the defaultSNMPPort parameter in the discovery.conf file.

  • SNMP Version

    Enables you to control the version of SNMP that the IP Manager uses to communicate with the system. Valid values for autodiscovery are V1, V2C, and AUTODETECT. The default is AUTODETECT, which means that discovery tries SNMPv2c first, and then SNMPv1 if necessary.

    If you specify an explicit SNMP version, V2C or V1, the IP Manager tries only the SNMP version that you specified. If the explicit version is different from the actual version that is supported by the system, the IP Manager generates a DiscoveryError with a message of “No response from SNMP Agent.”

  • Access Mode

    Determines which protocols are used to both discover and monitor the system and its components. Valid values for autodiscovery are ICMPSNMP and ICMPONLY. The default is ICMPSNMP, which means that both ICMP and SNMP protocols are used to discover and manage the system.

    When ICMPONLY is selected, discovery does not send SNMP polls to the system and cannot, therefore, discover the system and its components. Instead, the system is added to the modeled topology as a Host, and the system’s SNMP agent is added to the topology as an SNMPAgent. The host is monitored only for connectivity by sending ICMP polls to the host.

    Note the following:

    • Even if an ICMPONLY system does not have an SNMP agent, an SNMPAgent object is created for the system. The SysObjectID attribute of the SNMPAgent object is empty.

    • When an ICMPONLY system has multiple IP (v4 or v6) addresses that resolve to the same name, all IP addresses are retained. You must manually delete any IP address that no longer belongs to the ICMPONLY system.

    • An additional Access Mode option, SNMPONLY, is available to a system that is imported from a seed file, or is added to the topology by using the Add Agent command.

  • Community String

    Enables you to specify one or more read community strings that should be used to contact systems that match this filter. If no community strings are specified, autodiscovery uses the default read community string. “Read community strings” on page 202 provides information about default community strings.