Documentation forNetwork Topology Mapper

Network Selection Discovery Options

The NTM Discovery Wizard allows you to specify the range of IP addresses you want to discover. After IP nodes are discovered, you can select which ones you want to include on your map. The time it takes to complete a discovery scan relies heavily on the range of IP addresses you specify. The following provides guidelines and steps to create discovery ranges that will accurately discover the devices you want to map without including large number of other devices.

To better understand the network selection options you should consider the specificity of each option. Network selection discovery options are listed below in order from the most specific option to the most general option.

  1. Specific Nodes. This option discovers only the nodes you specify by IP address.
  2. IP Ranges. This option discovers only the nodes you specify by IP address range. The range can be any contiguous IP address block. Multiple ranges can be included to allow for discovery of non-contiguous ranges.
  3. Subnets. This option discovers the specified subnet and all networks directly connected to devices on the specified subnet.
  4. Seed Device. This option discovers all subnets that the specified device is aware of. By adding hop counts this option will discover devices several networks away.

Using Specific Nodes

This option is useful when you have an existing map and you want to add a specific node without having to discover a number of subnets or IP addresses.

Add specific nodes by their IPv4 address or IPv6 address. Add the node one per line.

Using Discovery IP Ranges

Discovery ranges allow you to specify contiguous IP address ranges for discovery. Node outside the specified range will not be discovered and the Hop Count discovery option is ignored for IP ranges.

For example a discovery using the range 10.110.1.1 to 10.110.3.255 defines a contiguous discovery range including all possible IP addresses between .110.1.1 and 10.110.3.255.

In contrast, a discovery including the starting address of 10.110.1.1 and the ending IP address of 10.110.2 255 along with an additional range of 10.110.3.1 to 10.110.3.255 will discover only those ranges and will not include the

10.110.2.0 subnet between them. IPv6 ranges are supported.

Using Subnets

Subnet discovery scans all specified subnets and subnets directly attached to devices included in the subnet.

For example, consider a discovery for the 10.110.1.0 subnet with a subnet mask of 255.255.255.0. If the discovery finds a router on the 10.110.1.0 subnet that also has interfaces on 10.10.20.0 and 192.168 5 0 subnets, those subnets will also be scanned for devices and connectivity. Additional subnets connected to those devices on the new subnets are not scanned.

After discovering subnets, clear the checkbox next to a subnet to remove that subnet from your map.

IPv6 subnets are supported.

Using Seed Devices

You can use a seed device to discover subnets, connectivity and network devices throughout your network. A seed device must be a layer 3 switch or router. NTM will scan the connection to the indicated device and use that information to scan directly connected devices.

After discovering directly connected devices, NTM will discover devices on connected subnets to the extent you have indicated in the Number of Hops option.

IPv6 see device addresses are supported.

Using a hop count greater than zero may greatly impact the time required to complete a scan.