Starting a discovery

After you configure a discovery, you can start and, if necessary, stop the discovery.

Make any required discovery configuration changes before you launch the discovery.

You can start the following types of discovery:

Discovery
Run a full discovery to discover your network for the first time, or to refresh the network topology if you know the network has changed.
Partial discovery
Run a partial discovery if you know that the changes to your network are limited to a small number of devices. You need to configure scoping and seeding as part of starting each partial discovery. If the relationship of the devices that are in scope with their neighboring devices has changed, then the neighboring devices may also be discovered. If the partial discovery needs to discover a large amount of devices based on connectivity information, then a full discovery is started.
Note: If you stop a running discovery, you must then do a full discovery before you are able to do a partial discovery.

To start a discovery, complete the following steps.

  1. Click the Discovery icon and select Network Discovery Status.
  2. Select the domain in which you want to run a discovery from the Domain menu. You can start to type the name of the domain, and matching domains are listed below the Domain field.
  3. Start a full or partial discovery:
    • To start a full discovery, click Start Discovery Start Discovery button only. The discovery starts.
    • To start a partial discovery, click the downward-facing arrow next to the Start Discovery button Start Discovery combo button. Can be used to start partial or full discovery. and select Start Partial Discovery from the menu (if a full discovery has not been run since the last time that the discovery engine, ncp_disco, was started, the option to start a partial discovery is grayed out). The Partial Discovery window is displayed. Specify the IP addresses and subnets that contain the devices to be discovered:
    1. Under Partial Discovery, select the required nodes and subnets.
    2. To add a new subnet or node, click New.
    3. Complete the fields as follows and click OK:
      Discover
      Select one of the following options:
      Identifier
      Type the required IP address.
      Subnet
      Type the required subnet and specify the number of netmask bits. The Netmask field is automatically updated.
      EMS Device Name
      Type the name of a device that was discovered through an Element Management System (EMS). You can type the nativeID, entity name, sysName, or display name.
      Note: When running a partial discovery of an EMS collector from the Discovery Status GUI, within the New Partial Discovery Node/Subnet window you must specify the EMS identifier value in the EMS Device Name field and not in the Identifier field. The Identifier field only accepts IP addresses.
    4. To add new scope zones, click Scope.
    5. To add a new discovery scope zone click New New button. To edit an existing scope zone, click the required entry in the list.
    6. Complete the fields as follows and click OK:
      Action
      Define the subnet range as an inclusion zone or exclusion zone. If the subnet range is an inclusion zone that you intend to ping during the discovery, click Add to Ping Seed List. Clicking this option automatically adds the devices in the scope zone as a discovery seed devices.
      Restriction: The Add to Ping Seed List option is not available for IPv6 scope zones. This prevents ping sweeping of IPv6 subnets, which can potentially contain billions of devices to be pinged. Ping sweeping of IPv6 subnets can therefore result in a non-terminating discovery.
    7. Click OK then click Go.
      When a full or partial discovery is running, the Start Discovery button is toggled off Start Discovery button. This button is grayed out while a discovery is running..
  4. To stop a discovery, click Stop Discovery Stop Discovery button. The discovery might take a short time to stop, during which time both the Start Discovery and Stop Discovery buttons are toggled off. If you stop a discovery, you cannot then do a partial discovery until after the next full discovery.
    Note: When you stop a discovery, the discovery cache is lost. This is why you must wait for the completion of the next full discovery before being able to perform a partial discovery. It is possible to configure the Discovery engine to save the discovery cache as the discovery is running, which would enable you to run a partial discovery immediately following the manual stop of a discovery. You can configure the Discovery engine to save the discovery cache by clicking Enabling Caching of Discovery Tables in the Advanced tab.
While the discovery is running, you can monitor the progress of the discovery.
Note: You cannot stop the discovery from the GUI in the correlating connectivity phase. Stopping the discovery process from the command line while the topology is being created can corrupt the discovery.

After the discovery is complete, the Start Discovery button is toggled on, and you can run another full or partial discovery at any time. If the Event Gateway Disco plug-in is enabled, then a new discovery can be triggered automatically when a reboot event (event ID of NmosSnmpReboot triggered by the rebootDetection poll policy) is received.