27 Apr
2016
27 Apr
'16
10:04 a.m.
On Apr 27, 2016, at 1:00 PM, Sean Conner <spc at
conman.org> wrote:
It was thus said that the Great Mouse once stated:
Not necessarily. You can do a lot better than linear search for route lookup. That can
be done with non-contiguous subnet masks too (I remember reading a paper from 30ish years
ago on that), but it takes less space -- fewer lookup table entries -- if the subnet masks
are contiguous because then each subnet is only one numeric range rather than several.
I think the main argument against non-contiguous masks is that it's a feature without
a purpose, and a popular source of bugs.
paul
And I spend over $80/month for DSL to a provider that gives me a /29
and a /60 from globally routed space. (That everything is now CIDR
blocks is another loss; I am not fond of the desupporting of
noncontiguous subnet masks, even though I can understand it - I'm the
only person I've ever heard of running that way other than for
testing.)
One benefit of contiguous subnet masks is that it makes routing faster.
It's still a linear search,