What is the name of an IP prefix with prefix length 31? (i.e. contains only 2 IP addresses)

At my job, IP prefixes with prefix length 31 (i.e. they only fit 2 IP addresses) are commonly described at "linknet addresses". Lately I have noticed that this term doesn't appear to exist outside of my company. If I do a Google search for "linknet address" or "link net address", I only find references to an ISP called "Linknet".

Does a term exist to describe this kind of IP prefix?

I'm asking because I'm developing a system where such IP prefixes are treated specially, so I need a term I can use to refer to them. I would prefer if this term wasn't one that was made up internally at my company.

Solution 1:

A /31 is most often used for creating a point to point link between two networks, since it can do so by only using two addresses. Hence the name, 'linknet'

You can read this RFC for more information.

Solution 2:

At former employer we'd have called this a "slash thirty-one" which saved two IPs over having to use a /30.

Nominally a /31 should not work, because the network and broadcast address take one IP each, leaving none for useful addressing. There were some items of customer equipment that couldn't handle it, so we had to use (or waste) a second /31 to make a /30.

The limitations on IPv4 availability make it practical to limit address wastage even a decade ago.

"linknet" would not have been used as a name, though if someone technical said "linknet" it would be obvious in context. A "point to point" link or network could have been said or used in documentation.