CIDR Utilization

Sat Oct 31 14:29:03 UTC 2015

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 at 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
>