Setting discovery filters

Use filters to filter out devices either before discovery or after discovery. You can filter out devices based on a variety of criteria, including location, technology, and manufacturer. Filters provide additional restrictions to those defined in the scope zones.

About this task

A filter is made up of one or more filter conditions. Filter conditions are defined in Object Query Language (OQL). You can add the following types of filter:
Prediscovery filters
Prediscovery filters prevent discovered devices from being polled for connectivity information.
Note: Use prediscovery filters to configure scope for non-IP devices in the network, as shown in the examples below.
Post discovery filters
Post-discovery filters prevent discovered devices from being passed to MODEL.
Note: To ensure that alerts are not raised for interfaces that are excluded by the post discovery filter, you must set the RaiseAlertsForUnknownInterfaces variable. To this, perform the following steps:
  1. Edit the $NCHOME/etc/precision/NcPollerSchema.cfg configuration file.
  2. Add the following line to the file:
    update config.properties set RaiseAlertsForUnknownInterfaces = 0;
The steps for adding, editing, and deleting filters are identical for both types.

To set the discovery filters:

Procedure

  1. Click the Discovery icon and select Network Discovery Configuration.
  2. From the Domain list, select the required domain.
  3. Click Filters.
  4. To use a filter in the discovery, select a filter from the Available filters list and click Select Filter.
    The filter is added to the Selected Pre-discovery Filter field or the Selected Post-discovery Filter field, depending on the type of filter.
  5. To remove a filter, select a filter from the Selected Pre-Discovery Filters or Selected Post-Discovery Filters list and click Deselect Filter.
  6. To add a new filter, or edit an existing filter, click Filter Library.
    The Filter Library page is displayed.
  7. Add or edit the filter as follows:
    Action Instructions
    Add a new filter Click Add and type the required name in the Name field.
    Edit an existing filter Select the required filter from the list.
  8. On the Basic tab, build the filter conditions as follows:
    1. Select the required field and comparator.
    2. Type the value for comparison with the selected field.
      See Configuring discovery filters for an example.
    3. Click Add New Row Add new row button or Delete This Row Delete row button to add or remove rows.
    4. Select All to combine multiple conditions in an AND relationship, or Any combine the conditions in an OR relationship.
    5. Click Save.
  9. Optional: On the Advanced tab, type the required SQL WHERE clauses. For multiple conditions, use an AND or an OR relationship as appropriate. Click Save.
    Note: The filter is actually based on standard OQL formatting, though the GUI refers to the SQL clause.
  10. Click Close to close the Filter Library, then click Save to save your filter settings.

Configuring discovery filters

You can use a prediscovery filter to refine scoping. The prediscovery filter applies to chassis and interfaces, whereas the postdiscovery filter applies to all entities. Take care when defining postdiscovery filters so that you do not inadvertently filter out objects such as VPNs, cards, or subnets.

Only pass non-IP devices to discovery
The following example filter is provided by default. It ensures that only non-IP devices are passed to discovery and interrogated further. This filter would exclude all IP-based devices.:
m_Protocol = 4
Only pass non-IP devices to discovery and exclude the non-IP devices with a specified unique key
The following example insert ensures that only non-IP devices are passed to discovery and the non-IP devices that are passed must not include the specified string in their unique Element Management System (EMS) key.
( m_Protocol = 4 )
    AND
( m_UniqueAddress NOT LIKE 'LONDON' )
Exclude devices with a specified object ID
The following example shows a filter condition for a prediscovery filter that excludes devices with a specified object ID.
m_ObjectId not like '1\.3\.6\.1\.4\.1\.2\.3\.1\.'
Restricting instantiation of a chassis based on entity name

The following example postdiscovery filter restricts instantiation of a chassis and its contents.

BASENAME != 'jane'
Restricting instantiation of multiple chassis

The following example postdiscovery filter restricts instantiation of a chassis and its contents.

snmpSystem->SYSDESCR NOT LIKE ' device'