Excel IPv4 Subnet Planner
Visually plan your CIDR subnets and firewall ranges with this handy Excel spreadsheet.
If you have a large (Wide-area) Network that you need to segment into VLANs of varying sizes – this spreadsheet can help you organize them into hierarchical ranges.
In the image above you can see that all of “WA1” is 10.0.16.0/21 so we can set global ACL’s at that level. All the corporate staff fall into 10.0.16.0/22 and Guests 10.0.20.0/23.
So as we progress from larger ranges to smaller, more defined subnets, then we can define ACL’s and firewall rules for global and/or granular policies respectively.
This kind of subnetting is much easier when done visually.