IPv4 CIDR Address Allocation

A utility to manage allocating and deallocating CIDR networks.

Problem Statement

CIDR address allocation is a complex problem. Some might think it is very close to the memory allocation problem. But it's more complex than that because of recursively dividing the address space into two till a best fit is found.

For a clearer view of the problem, let's say you have an apple and you can cut a unit in half only. So if a friend asked for 1/4th slice, you would have to cut it twice. This would leave you with two slices, a 1/4th slice and a 1/2 slice. If another friend now asks for a 3/4th piece of apple, you can't allocate him that because you need to give him a single piece only.

Let's make things clear with an example. Let's say you have a network 10.10.0.0/20. Now, the Computer Science department posts a requirement of a 1000 host machines. This means that the network you'll allocate will be /22 subnet from the given network. To get to that, you divide the network into 2 parts and you get a /21 network. Now you pick the left one (for ease of policy) and divide it into 2 again and you get a /22 network to allocate.

Setup

Linux

Make sure you have Python 2.7 installed on your machine. Install the bokeh and ipaddr packages:

sudo pip install bokeh

sudo pip install ipaddr

Windows

While installing Python, make sure you choose the "Add Python.exe to PATH" option. Open the command prompt and install bokeh and ipaddr modules for Python

python -m pip install bokeh

python -m pip install ipaddr

Usage

• Start the script in interactive mode

python -i ipam.py

• Initialize your network address space

ipam = IPAM("10.10.0.0/24")

• Allocate subnets according to your size requirements NOTE: Subnets allocation policy is left-first.

ipam.add(1000)
ipam.add(100)
ipam.add(250)
ipam.add(60)

• View allocations

ipam.plot()

TODO:

• Ability to delete subnets
• Other subnet allocation policy