IP Addressing
When it comes to your homelab, IP addressing is important. There are a few points to consider before settling on an IP addressing scheme. Keep in mind that changing IPs or mixing and matching IP schemes is not recommended and can be difficult.
Picking a Supernet
Section titled “Picking a Supernet”First things first, you want to pick a supernet. Typically, this will be one of the three RFC 1918 private address ranges. I suggest using 10.0.0.0/8 because this gives you well over 16 million IPs to play with - which comes in very handy when implementing VLANs and avoiding overlaps.
| RFC1918 name | IP address range | Number of addresses | Largest CIDR block (subnet mask) | Host ID size | Mask bits | Classful description1 |
|---|---|---|---|---|---|---|
| 24-bit block | 10.0.0.0 – 10.255.255.255 | 16,777,216 | 10.0.0.0/8 (255.0.0.0) | 24 bits | 8 bits | single class A network |
| 20-bit block | 172.16.0.0 – 172.31.255.255 | 1,048,576 | 172.16.0.0/12 (255.240.0.0) | 20 bits | 12 bits | 16 contiguous class B networks |
| 16-bit block | 192.168.0.0 – 192.168.255.255 | 65,536 | 192.168.0.0/16 (255.255.0.0) | 16 bits | 16 bits | 256 contiguous class C networks |
Avoiding 192.168.0.0/16
Section titled “Avoiding 192.168.0.0/16”I strongly recommend avoiding the 192.168.0.0/16 range of IPs due to backward compatibility issues. The reason is that some older networking devices or software may not recognize classless networking. While you can do 192.168.0.0/25, this may not make some legacy devices happy. Usually, with classful, you can go smaller, not larger. Although this is rare, you can occasionally run into problems.
Footnotes
Section titled “Footnotes”-
Classful addressing is obsolete and has not been used in the Internet since the implementation of Classless Inter-Domain Routing (CIDR), starting in 1993. For example, while 10.0.0.0/8 was a single class A network, it is common for organizations to divide it into smaller /16 or /24 networks. Contrary to a common misconception, a /16 subnet of a class A network is not referred to as a class B network. Likewise, a /24 subnet of a class A or B network is not referred to as a class C network. The class is determined by the first three bits of the prefix.[^2] ↩