HP Netsight manual Discovering Nodes

Discovering Nodes

3.If necessary, place the cursor in the Subnet Mask field and type the subnet mask for the subnet that you wish to discover. Note that the value set here will determine the number of IP addresses which are included in the defined subnet, regardless of whether or not this value correctly reflects the number of devices each of your subnets contains. For example, a Class B network typically defines the third byte of the IP address as the subnet identifier, and the fourth byte as the host identifier. In this kind of network, each subnet (as defined by each possible value of the third byte) can contain a maximum of 256 nodes on it (the number of possible values for the fourth byte). However, if you incorrectly identify the subnet mask for such a network as 255.255.0.0, the discover application interprets this to mean that each subnet has 65,536 IP addresses (256 possible values of the third byte, times 256 possible values for the fourth byte). Since each discover script is limited to querying a maximum of 2000 addresses, this kind of incorrect mask setting would prevent you from completing your script. By default, the Subnet Mask will be set to 255.255.255.0, limiting the size of the subnet to a maximum of 256 devices. The Nodes field just below the Subnet Mask field indicates the number of nodes the Discover application understands your defined subnet to contain; it will update once you have saved your subnet changes, closed the Subnet Properties window, and re-opened it.

NOTE

The Nodes field in the Subnet Properties window is not the same as the nodes value displayed in the View—>Subnetswindow (see Figure 3-20, page 3-28); that value indicates the actual number of nodes in the central node database that reside on the defined subnet.

4.On the General page of the Subnet Properties window (Figure 3-7), place the cursor in the Name text box, and type in a name for your subnet entry. By default, manually-created subnets are assigned the name New Subnet X, where X will increment as necessary to create a unique name. Automatically-created subnets are assigned the subnet address as their default name.

Creating and Modifying Discover Scripts 3-9