Creating Discovery Ranges

Every discovery range you create must be associated with a network view. If no network views are specifically defined in your deployment, your discovery ranges are automatically assigned to Network 1. For the first discovery of the network, this network view is automatically assigned to the SCAN1 port when you set up the appliance using the configure server command.

If more than one network view exists, you can choose the network view with which the discovery range will be associated, by clicking the Network View drop-down menu. If only one network exists in NetMRI, this setting does not appear. The chosen network view must also be associated with a scan interface. Otherwise, discovery does not take place. Unassigned network views that do not have an assigned scan interface or virtual scan interface appear with theicon in discovery ranges configuration. For more details, see Configuring Network Views.

Network views can contain multiple discovery ranges. So when you create other ranges, you can assign the same network view to each. However, you can assign each discovery range to only one network view. Also, ensure that the ranges you assign to each network view make sense. Selecting the network view in an Operations Center environment also involves other details. For more information, see Defining Discovery Ranges on Operations Center Collectors.

You can define discovery ranges that will be excluded from management. This is useful for devices you may not want to manage, but want to know about for inventory purposes. End Host network segments are a good example.

To create a discovery range, complete the following:

1. Obtain or calculate the network range values. You can define a Network address (expressed as CIDR: in effect, a subnet prefix), an IP range, or an IP pattern.
2. Go to the Settings icon > Setup > Discovery Settings > Ranges.
3. Click New.
4. Select an appropriate way to specify the range: 
   • CIDR: Enter the IP Prefix value and its CIDR subnet value in the drop-down.
   • IP Range: Specify an IP range using a beginning and ending value.
   • IP Pattern: Specify a wildcard pattern for matching IP addresses.
5. For Discovery Mode, choose one of the following:
   • Include in Discovery: Any device found matching that range is discovered and managed by NetMRI.
     Discovery gives the highest precedence to devices found in an Include in Discovery range, ensuring they will be the first to appear in information tables in the appliance.
   • Exclude from Discovery: Instructs NetMRI to ignore the specified values and not discover them through any of the specified protocols. Ranges set to an Exclude from Discovery setting are simply excluded, given the lowest precedence, and will not be discovered.

   • Exclude from Management: Indicates that NetMRI discovers any device found matching that range, but NetMRI does not manage or collect data from the device. Network devices found in an Exclude from Management range are given moderate precedence and will, over time, appear in information tables applicable to unmanaged devices. End host network segments are an example.
     If you are discovering end-host subnetworks for Switch Port Management, choose the Exclude From Management option for the end host discovery ranges.
     The Discovery Status Precedence setting (Settings icon > General Settings > Advanced Settings > Discovery group > Discovery Status Precedence) governs the global setting for exclusion ranges. Changing this setting to Longest Prefix Match enables an exclusion range to contain smaller IP ranges that can be matched against to allow discovery. For example, you can exclude a /23 network, but include a /24 prefix within the EXCLUDE range because the /24 is a longer prefix.

6. To use a discovery ping sweep for discovery on IPv4 networks, select Enable Discovery Ping Sweep.
   This implies a probe that uses a range of packet types to detect the presence of a system on each IP in the specified range, with ICMP Echo, ICMP Timestamp, TCP SYN to port 80, and TCP SYN to ports 161, 162, 22, and 23 (for the SNMP, SNMPTRAP, SSH, and TELNET services correspondingly). A ping sweep is not available for IPv6 network values. For more information on ping sweeps, see Defining Group Data Collection Settings.
   The discovery ping sweep feature differs from the Smart Subnet ping sweep in the following ways:

   • The discovery ping sweep runs only against the specified range.

   • The sweep runs regardless of the range size.

   • The sweep runs regardless of the number of discovered devices within the specified range.

7. If more than one network view exists, you can choose the network view with which the discovery range will be associated in the Network View drop-down menu. If only one network exists in NetMRI, this setting does not appear.
   Unassigned network views that do not have an assigned scan interface or virtual scan interface appear with a caution icon in the discovery ranges configuration.

8. Select the Enable Discovery Blackout checkbox and then click its Scheduling icon.

9. In the Discovery Blackout Schedule dialog box, define your schedule as follows:

   • In the Recurrence Pattern menu, choose how often you want to execute the blackout period. You can select Daily, Weekly, Monthly, or Yearly.

   • If you choose Daily, complete the following:

     • Choose the execution time.

     • Select Every Day or Every Weekday.

     • Specify the duration.

   • If you choose Weekly, complete the following:

     • Choose the execution time.

     • Select one or more days from Sunday through Saturday.

     • Specify the duration.
   • If you choose Monthly, complete the following:
     • Choose the execution time.
     • Day __ of every __ month(s): Specify for the discovery blackout to be executed on day-of-month X of every Y month. Month numbering starts with January. Examples:
       Day 5 of every 1 month(s): means the blackout is executed on the 5th of the current and each next month.
       Day 5 of every 2 month(s): means the blackout is executed on the 5th of January, March, May, July, and so on. 

     • Specify the duration.

   • If you choose Yearly, complete the following:
     • Choose the execution time.
     • Select the day and the month when you want to execute the blackout period.
     • Specify the duration.
       For more information about discovery blackouts and change blackouts, see Defining Blackout Periods.
10. Select Enable Change Blackout and then click its Scheduling icon. Follow the instructions for the Enable Discovery Blackout setting in the previous step.
11. To add the new discovery range to the Range table, click Add.