netconnect.tar.gz

This course is a quick guide for understanding the internet protocol standard IPv4, including its packet structure, subnetting, and address configuration on hosts and routers. It also discusses the sixth version, IPv6, and its addressing scheme, subnetting, and coexistence with IPv4.

A Quick Guide for IP Subnetting

# Next network
Let's ask a question: What's the next network? 

When it comes to subnetting, we are not only interested in the current network but also in the next network. Let’s suppose we have the following network:

```
192.168.0.0/27
``` 

The total number of IP addresses from a network with a mask of `/27` is $32$. (because $32-27 = 5,$ and  $2^5 = 32$). It also tells us that the next network will start after $32$ IP addresses from the starting address. Hence, the next network will be `192.168.0.32/27`. Similarly, we can get addresses of the next networks with an increment of 32: `192.168.0.64/27`, `192.168.0.96/27`, and `192.168.0.128/27`.

What is the next network of `84.88.32.24/29`?

<p>What is the next network of <code>84.88.32.24/29</code>?</p>


Take a look at the following table to see some other examples:

align-center

If we have a mask of `/24`, the total number of IP addresses is $256.$ For any field in an IP, the maximum value can be between $0$ and $255$ (we can’t have the number $256$). We can’t have this IP `192.168.0.256`, but we can have `192.168.1.0`. 

To understand this better, let’s do a visualization exercise and think of a watch. If we have a clock that reads as 11:59 (corresponding to `192.168.0.255`), what time will it be in 1 minute? Would it say 11:60? Assuming the clock is functioning perfectly, it would say 12:00 (corresponding to `192.168.1.0`). Our situation corresponds very well with this thought exercise.  Whenever we have a network that ends in `192.168.0` `.255` and we want to move on to the next network, we’ll get the value `192.168` `.1.0`.

# IP subnetting based on the number of devices

Let's design a network for a firm that has three departments: Sales, Marketing, and IT.

Each of these departments will have certain devices (laptops, printers, servers, and so on.) that require an IP address to communicate with each other and the internet.
 
Suppose we need 15 IP addresses for Sales, 7 for Marketing, and 129 for IT, and the available address space is `10.23.0.0/16`.

This addressing space will contain the following: 

1) The maximum number of IP addresses from a network mask of `/16` is $65536$ $(32-16=16, 2^{16} = 65536).$
2) First IP: `10.23.0.0`. Last IP: `10.23.255.255`.
3) The usable IP addresses are from `10.23.0.1` to `10.23.255.254`. 

Assuming each IP address as costing $1 per month, we’d risk paying $65,536 per/month for the IPs alone. Our goal with subnetting is to use as few IP addresses as possible to reduce our costs. 

We’ll always start subnetting with the biggest network (based on the total number of IP addresses/devices required):

1. IT requires 129 IPs.
2. Sales require 15 IPs.
3. Marketing requires 7 IPs.

Now, let’s answer the following questions:


Network - IP	First IP	Last IP	Next Network
192.168.0.0/24	192.168.0.1	192.168.0.255	192.168.1.0/24
10.0.0.0/27	10.0.0.1	10.0.0.31	10.0.0.32/27
10.10.0.128/26	10.10.0.129	10.10.0.191	10.10.0.192/26

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IP Subnetting based on the Number of Devices

Next network