PRTG Manual: Using the Discovery Wizard
The Discovery Wizard steps you through the process of running a network discovery. First, it helps you enter a few necessary settings, and then it initiates the discovery. The following settings must be specified:
The discovery settings entered in the wizard will be saved under this name. It can be anything you want, but cannot be empty. (See Network Discovery Settings for more information.)
A discovery runs in two major phases: 1) Find devices on the network, and 2) Discover detailed information about each device. For the first phase, there are two major techniques for finding devices on a network: Ping Sweep and ARP Cache. The Discovery Method property specifies which of these two device discovery techniques you want to use. To help you select the one you want, both approaches are explained next.
Ping Sweep
Because you are familiar with your network’s structure, you know what subnets you have, and what IP address ranges are in use on your network. Of course, not all IP addresses in these ranges are currently in use, but some of them are. For a Ping Sweep discovery, you simply specify ranges of IP addresses that should be searched for devices, and UVexplorer will ping every address in those ranges to determine which addresses correspond to actual devices. The IP address ranges to be searched are specified in the ‘Seed IP Addresses / IP Ranges’ section. For Ping Sweep discoveries there are two things to keep in mind: 1) Ping Sweep only works on devices that can be successfully pinged. If your network or devices are configured to disallow ping, Ping Sweep will not work, 2) The more IP addresses that need to be pinged, the longer discovery will take. Specifying large IP address ranges can cause discovery to take a long time. Therefore, you should specify the smallest IP address ranges possible.
ARP Cache
The alternative to Ping Sweep is ARP Cache. Rather than doing a brute-force, exhaustive search of your IP address space as Ping Sweep does, an ARP Cache discovery intelligently discovers active IP addresses (and therefore devices) by inspecting the ARP caches on your network devices. To run an ARP Cache discovery, you must specify the IP addresses of one or more “seed devices”, which are the devices where the discovery will begin. The seed devices are typically your core network switches or other network devices that have large ARP caches containing IP addresses of other devices on your network. By interrogating the ARP caches on the seed devices, UVexplorer finds the IP addresses of other devices on your network. UVexplorer then interrogates the ARP caches on these other devices to obtain even more device IP addresses, and so on. In this way, UVexplorer crawls your network, and eventually finds most of the devices on your network. The IP addresses of the seed devices are specified in the ‘Seed IP Addresses / IP Ranges’ section. ARP Cache discoveries are typically faster than Ping Sweep discoveries, but they do require that SNMP be enabled on your network devices so that their ARP caches are accessible to UVexplorer.
For Ping Sweep discoveries, this field is used to enter the IP address ranges that should be pinged. For ARP Cache discoveries, this field is used to enter the IP addresses of the seed devices that are used to initiate the discovery (typically core network devices). To specify the desired IP addresses, enter one or more lines in the text field, each of which should contain one of the following:
▪An individual IP address (e.g., 192.168.30.1)
▪An IP subnet consisting of an IP address and subnet mask length (in bits) separated by a forward slash (e.g., 172.16.0.0/24)
▪An IP address range consisting of minimum and maximum addresses separated by a dash (e.g., 10.0.0.32 – 10.0.0.96).
Pressing the ‘Default Gateway(s)’ button will automatically enter the IP addresses of the local computer’s IP gateways. Pressing the ‘Default Subnet(s)’ button will automatically enter the subnets that the local computer is a member of. Pressing the ‘Clear’ button will clear the text field.
This section lets you select the network protocols and credentials that should be used during discovery. It displays a list of all credentials that have been previously defined (see Managing Device Credentials for more information). The row for each credential contains a checkbox that you can check to select the credential. The checkbox in the table header can be used to easily select ALL credentials. When you select a credential, you are both telling UVexplorer to use that protocol during discovery, and which credential to use with that protocol. Only the selected protocols and credentials will be used during discovery.
You may select multiple credentials for the same protocol, in which case UVexplorer will try them all on each device until it finds one that works. The order of the credentials in the table is significant, because it determines the order in which UVexplorer tries the credentials during discovery. You can use the ‘Move Up’ and ‘Move Down’ buttons to select a credential, and move it up or down in the table.
The ‘Add’ button can be used to create new credentials, or modify existing credentials.
UVexplorer uses the WMI protocol to collect inventory information from Windows devices. In order to collect WMI inventory, you must specify appropriate Windows(WMI) credentials. WMI data collection can be time-consuming, so this setting lets you specify how much WMI data to collect. If you select ‘Collect Basic Windows Inventory’, only basic WMI data will be collected. This will result in the fastest possible discovery. If you select ‘Collect Full Windows Inventory’, detailed WMI data will be collected. This will result in a slower discovery that produces much more detailed inventory information for Windows devices.
