Re: ifconfig v2

[Robert Elz <kre%munnari.OZ.AU@localhost>]

    Date:        Wed, 12 Jun 2013 09:07:43 -0400 (EDT)
    From:        Mouse <mouse%Rodents-Montreal.ORG@localhost>
    Message-ID:  <201306121307.JAA02803%Chip.Rodents-Montreal.ORG@localhost>

  | Why?  What harm are they doing that outweighs (to you) breaking an
  | occasionally useful (if little-used) facility that's been there pretty
  | much since day one?

I am fairly sure that the IETF decided to abandon all support for those
things back when the router requirements rfcs were being written (mid 90's)
- they had their uses back when subnets were first invented, but lack of
support from some major vendors meant that in practice they couldn't be used
in a lot of sites, even where there was some minor benefit to be gained (which
is really just avoiding renumbering, as any even half sane use of non-contig
masks is just a 1:1 mapping from another numbering scheme using contig masks).

The real killer for them however is that no-one has even been able to
describe (let alone make work) what is supposed to happen when a network
has two different sets of non-contig masks applied - and since there is
no way to prevent that if non-contig masks are allowed at all, and as they
add no real value (just a minor convenience) - they were dropped.

kre