IP Address Management

[smvitayush1]

Hi Everyone,

Could any one please explain the difference between Splitting and Allocation a IP address block.

Say if I have 10.0.0.0/24 (254 hosts) available. My requirement is to get a /25. 

Could anyone explain how Splitting and Allocation works?

Thanks a lot.

[Hector Gustavo Serrano Gutierrez]

Splitting 10.0.0.0/24 into two /25s will result in 2 different subnets that you can configure anywhere in your network.

First network:

10.0.0.0/25	Network.
10.0.0.1/25	First IP available that can be assigned.
10.0.0.126/25	Last IP available that can be assigned.
10.0.0.127/25	Broadcast IP for this network.

Second network:

10.0.0.128/25	Network.
10.0.0.129/25	First IP available that can be assigned.
10.0.0.254/25	Last IP available that can be assigned.
10.0.0.255/25	Broadcast IP for this network.

Furthermore, you can keep 'splitting' any of those into 'longest' prefix-lenghts, /26, /27, /28, etc. This is called VLSM (Variable Length Subnet Mask)

This process is just called subnetting.

[smvitayush1]

Hi Hector thanks for the reply.

Could you also tell what happens if I allocate. What happens to the parent subnet 10.0.0.0/24 ( I mean what would be the Network, First and last ip).

The same thing about the IP subnet which I will get /25 after allocation /24.

Thanks a lot. :)

[Hector Gustavo Serrano Gutierrez]

If you 'split' 10.0.0.0/24, instead of allocate a single network, you will be able to allocate 10.0.0.0/25 & 10.0.0.128/25 (2 subnets).

In my last response I included the addressing for the new subnets.