Hello Trevor
Yes, you’re correct. In the context of subnet masks, a smaller CIDR notation (like /19) actually represents a larger network because it includes more IP addresses. Conversely, a larger CIDR notation (like /21) represents a smaller network with fewer IP addresses.
Even so, the “le” and “ge” operators used by the prefix lists always refer to “less than or equal to” and “greater than or equal to” in a numerical context. In other words, /20 is considered “ge” /19.
Think about it this way:
- “Greater than” and “Less than” are strictly mathematical terms, so these act directly upon the actual numbers being used. These are the operators used in the prefix lists.
- The terms “Larger” and “smaller” are typically used to refer to prefix sizes, where a prefix of /19 results in a larger subnet than a /20 prefix.
Does that make sense? It can be a bit counter-intuitive, but just remember that the ‘le’ and ‘ge’ operators are referring to the CIDR notation number, not the actual size of the subnet.
I hope this has been helpful!
Laz