netmask for loopback interfaces

From: Mike Karels <>
Date: Wed, 03 Nov 2021 23:01:02 UTC
I have a pending change to stop using class A/B/C netmasks when setting
an interface address without an explicit mask, and instead to use a default 
mask (24 bits).  A question has arisen as to what the default mask should 
be for loopback interfaces.  The standard is added with an 8 bit 
mask currently, but additions without a mask would default to 24 bits.  
There is no warning for missing masks for loopback in the current code.  
I'm not convinced that the mask has any meaning here; only a host route 
to the assigned address is created.  Does anyone know of any meaning or 
use of the mask on a loopback address?