[openstack-dev] [neutron] Neutron should disallow /32 CIDR

Paul Ward wpward at us.ibm.com
Fri Jan 24 17:43:42 UTC 2014

Given your obviously much more extensive understanding of networking than
mine, I'm starting to move over to the "we shouldn't make this fix" camp.
Mostly because of this:

"CARVER, PAUL" <pc2929 at att.com> wrote on 01/23/2014 08:57:10 PM:

> Putting a friendly helper in Horizon will help novice users and
> provide a good example to anyone who is developing an alternate UI
> to invoke the Neutron API. I’m not sure what the benefit is of
> putting code in the backend to disallow valid but silly subnet
> masks. I include /30, /31, AND /32 in the category of “silly” subnet
> masks to use on a broadcast medium. All three are entirely
> legitimate subnet masks, it’s just that they’re not useful for end
> host networks.

My mindset has always been that we should programmatically prevent things
that are definitively wrong.  Of which, these netmasks apparently are not.
So it would seem we should leave neutron server code alone under the
assumption that those using CLI to create networks *probably* know what
they're doing.

However, the UI is supposed to be the more friendly interface and perhaps
this is the more appropriate place for this change?  As I stated before,
horizon prevents /32, but allows /31.

I'm no UI guy, so maybe the best course of action is to abandon my change
in gerrit and move the launchpad bug back to unassigned and see if someone
with horizon experience wants to pick this up.  What do others think about

Thanks again for your participation in this discussion, Paul.  It's been
very enlightening to me.
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