Networking

Fundamentals of IP Addressing

Understanding IP addressing is a fundamental requirement for almost any technician.
In this Tech tip we will give you the basic fundamentals needed in order to understand what is an IP address is, how IP addresses are broken down and how sub-netting works.

Definitions and terms to know

IP Address: Just like your street address where you live to allow the post man to find you, an IP address is a logical numeric address that is assigned to every single computer, printer, switch, router or any other device that is part of a TCP/IP-based network

Subnet: There are millions of IP addresses made available for you to use. A subnet is an identifiable portion or grouping of IP addresses that make up your network of devices.

Subnet Mask: the Subnet mask acts similar to your post code. It is a 32-bit number used to differentiate the network component of an IP address. It does this by dividing the IP address into a network address and host address.

IP Addresses

The “IP” in IP addresses refers to the Internet Protocol. A protocol is the set of rules which define how communication is handled between devices. IP addresses allow network resources to have a unique address in which others can communicate to. Just like the postal system uses street address numbers and names, A network device uses and IP address as an address that tells other network device where it is located. Assuming that the two communicating computers are on the same network, or that the different computers and devices in between can translate requests across networks, the computers should be able to communicate with each other.

An IP adores is broken into 4 numbers separated by dots. Any one of these numbers between the dots can be between 0 and 255

Examples IP addresses include:

145 . 67 . 87 . 231

34 . 243 . 44 . 155

We all know a computer’s language is basically 1’s and 0’s. So naturally this address can be converted to binary. A number like 145 . 67 . 87 . 231 could be written in binary as:

10010001 . 01000011 . 01010111 . 11100111

Each of these binary components is referred to as an octet as each component contains 8 bits (O or 1).

Why is each number limited to 0 to 255?

IP addresses are limited to 32 bits (4 x 8 bits) as seen in the binary address above. The maximum number of combinations of binary numbers you could have in an octet is 256 (mathematically calculated as 28). The largest IP address you could have would be 255.255.255.255.

The difference between IPv4 and IPv6

With the increasing popularity of IOT and mobile devices, an issue has arisen where we are now seeing too many devices connecting to the internet and not enough IP addresses within the IPv4 address scheme to cater for the number of devices. IPv4, which is the 4th version of the protocol, is the most common version of the IP protocol used by most systems today. The newest revision of the internet protocol called IPv6t will improve on the limitations of IPv4 address space. Thew IPv6 address space will be much larger than the traditional IPv4 address space. You will start seeing more and more IPv6 address as we start to run out of IPv4 addresses.

IPv4 Addresses

IPv4 addresses are 32-bit addresses. Each byte, or 8-bit segment of the address, is divided by a period and typically expressed as a number 0-255.

A typical IPv4 address looks something like this:

192 . 168 . 0 . 5

IPv6 Addresses

IPv6 addresses are written out as eight segments of four hexadecimal digits. Hexadecimal numbers represent the numbers 0-15 by using the digits 0-9, as well as the numbers a-f to express the higher values. So 10 is represented as A and 11 as B and so forth. typical IPv6 address might look something like this:

2001 : 8fe0 : fe80 : b897 : 8990 : 8a7c:99bf : 323d

There are many difference between the IPv4 and IPv6 address scheme but the most obvious being a much larger adress space. IPv6 expresses addresses as an 128-bit number. To put that into perspective, this means that IPv6 has space for more than 7.9×1028 times the amount of addresses as IPv4. This will definitely aid in the issue wit the ever growing popularity of IoT devices and the increased number of devices that will require IP addresses in the future.

What are Subnets

A subnet (short for “subnetwork”) is defined as a group of IP address that make up a network. A subnet is used to separate your network or IP address range to represent smaller networks. For example you might want to separate all of your machines at one geographic location, department or by floor in your building.

The less technical reason why sub-netting is used is for users or technicians to easily distinguish what IP address belongs to which location. If a technician finds an IP address is generating a heap of traffic the location can be easily identified.

More technically, devices often uses broadcasts in order to develop communication with other devices on the network. A broadcast is when a device sends packets out to all devices on a network to investigate where each device is located. By sub-netting we can make these broadcast networks smaller and reduce unneeded traffic across your whole network.

Public Vs. Private IP Addresses

Technically, if all the possible combinations of IP addresses were available, there would be about 4,228,250,625 IP addresses for use. This might seem a lot but this number is easily used by the number of computers and devices that are connected to the internet. To resolve the issue of limited Public IP address there are some address ranges that are set aside purely only to be used for private use.

Here why and how private IP addresses help.

The concept of a private address is similar to that of a private extension in an office phone system. Someone who wants to call an individual in a company would dial the company’s public phone number, through which all employees can be reached. Once the public number is reached the caller would enter in the private extension number of the person to whom they wished to speak. Private IP addresses are to IP addresses what extension numbers are to phone systems. The phone system would only need 1 public number which would be reachable by the outside world where all internal numbers exist internally.

Private IP addresses allow network administrators to extend the size of their networks. Just like the phone system mentioned above, a network could have one public IP address that all traffic on the Internet sees, and hundreds – or even thousands – of hosts with private IP addresses on the company subnet.

Anyone can use a private IP address on the understanding that all traffic using these addresses must remain local to the network. You cannot use a private IP address to represent a domain or website because it would not be publicly reachable on the Internet.

A typical network setup using public and private IP addresses with a subnet mask would look like:

Conclusion

We have covered a lot of information here. Here are some basic points on some of the information which has been shared.

  • For components and systems to communicate on a network, each needs a unique address. For computer networks using the Internet Protocol, these addresses are numeric and are commonly referred to as IP addresses.
  • To make efficient use of IP addresses we separate our network into logical groupings of devices. A subnet is a logical organisation of connected network devices.
  • Think of the Internet Protocol as simply the rules of communication which device on a network use to communicate with each other..
  • IPv4 addresses are written in the form of x.x.x.x.
  • Subnetting involves dividing the network into smaller portions called subnets.
  • Public versus private IPs are similar in theory to public telephone numbers versus private extensions.

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