[185626] in North American Network Operators' Group
Re: CIDR Utilization
daemon@ATHENA.MIT.EDU (inetjunkmail)
Sat Oct 31 18:04:49 2015
X-Original-To: nanog@nanog.org
In-Reply-To: <CA+OqHhABBFK6YQ9nQCRfOvP58maV5Kx4wj3oYPpFWrDyJDcapg@mail.gmail.com>
Date: Sat, 31 Oct 2015 10:29:03 -0400
From: inetjunkmail <inetjunkmail@gmail.com>
To: John Steve Nash <john.steve.nash@gmail.com>
Cc: nanog@nanog.org
Errors-To: nanog-bounces@nanog.org
Attached is a perl script I wrote for a coworker that you can tweak as
you'd like. It's designed to log into a router and dump the route table(s)
and find used/unused subnets in a given supernet. Available routes are
green and used routes are red. Yellow routes are routes where we have
route and a more specific route so the first route is probably an aggregate
and there _may_ be open space available.
On Fri, Oct 30, 2015 at 8:51 PM, John Steve Nash <john.steve.nash@gmail.com>
wrote:
> Hi,
>
> I'm looking for any tool or a way I could specify a CIDR and the prefixes
> that are being used within this CIDR and the tool show me all free
> supernets.
>
> Example:
>
> 192.168.0.0/24 - CIDR
>
> Used subnet's:
>
> 192.168.0.1/32
> 192.168.0.8/27
> 192.168.0.64/26
> 192.168.0.68/32
> 192.168.0.96/29
>
> Tool Result => Free Subnet's:
>
> 192.168.0.2/31
> 192.168.0.4/30
> 192.168.0.32/27
> 192.168.0.128/25
>
> Regards,
>
> John
>
