Discovering Your Enterprise › How Subnet Filters Work

How Subnet Filters Work

Using a subnet filter on large networks with multiple large subnets is advantageous because you can limit your search to certain subnets within the network, which can mean a shorter Discovery process.

Use a subnet filter to do the following tasks:

• Limit the scope of Discovery by confining it to a certain range of subnets and devices. For example, if you use the subnet filter 172.24.*.*, for example, only the subnets from 172.24.1.0 to 172.224.255.0 are searched. If there is a subnet called 172.119.1.0, that subnet is not searched because it does not fall in the range specified by the subnet filter.
• Enter a range of as many as ten filters. The filter statement uses a comma separated format of a1.b1.c1.d1,a2.b2.c2.d2,…a10.b10.c10.d10. Only those subnets passing through filter1 (a1.b1.c1.d1) or filter2 (a2.b2.c2.d2) or filtern (up to 10) will be searched and created as TNG/IP_Subnet.
• Use the default subnet filter of *.*.*.*, which does not limit the scope of the Discovery process. After the selected subnets are searched by Discovery, they are placed on a list in the right pane of the Discovery Subnet Management dialog.

You can also use the dscvrbe command to limit Discovery to specific subnets to discover, a range of IP addresses to discover, a range of subnets to discover, or subnets to exclude subnets from the Discovery process. You define the subnets in a text file and then specify this text file using the -8 parameter of the dscvrbe command. This functionality is available only when you use the dscvrbe command.