Best Static IPv4 Address Organization Scheme

[thomas-hn]

Hi,

I am wondering if there is a cool idea, best practice, etc. for the assignment/organization of static IPv4 addresses on devices with multiple network interfaces on different subnets (to easily see which IPs belong to which device).
For example, a router has a downstream interface where it acts as a gateway and, therefore, uses the x.x.x.254 address. However, on its upstream interface the router is only a "client" to the next router and, therefore, uses maybe the x.x.x.100. So it is hard to see that the 100 on subnet A and the 254 on subnet B is on the same device.

If a device is not a router but acts in multiple VLANs, it would be nice to have something like x.x.x.25 and y.y.y.25 on its interfaces, so that it is (for humans) easy to remember that 25 is this specific device in all subnets. I am fully aware that this will not work in all use-cases, but an uncontrolled growth of IP assignments could be even worse.

Simply assigning everything via DHCP and not considering any static addresses is not an option, because subnets like "Management" shall use static addresses that the management subnet still works in case a DHCP server would fail.

How do you organize your static IPv4 addresses in your subnets?

Thanks a lot in advance,

Thomas

[lilsense]

two things, IPAM (IP address Management) and drawings.

[thomas-hn]

Thanks a lot for the hint.
For IPAM tools I already had a look and found some interesting tools.

What tool are you using for the drawings? Is there any free tool available for such drawings (talking about special network drawing tools and not stuff like Visio, Inkscape, etc.)?

[lilsense]

you can use https://www.diagrams.net/

[sphbecker]

IPv6 does this by design, but with IPv4 you have to document it yourself.

One bit of advice when assigning static IP addresses to hosts, try to think of them as base-2 numbers, not base-10 numbers. What I mean, is don't do something like "Server are .20-.30, Printers are .50-.70." Instead use numbers like "Servers are .16-.31, Printers are .64-.95." That way, even if you never plan to divide the network up into vlans, you can still write rules based on the type of devices, so servers would be 10.0.0.16/28 and printers are 10.0.0.64/27. If you do think you might want to create VLANs at some point, avoid using the first, second and last addresses in each range as they would need to be the network, gateway and broadcast addresses respectively on a vlan.