Private IP Address
Based on the original design of the Internet, every host on every network should have a real routable IP address. For example, an organization that wanted to access the Internet would complete some paperwork, describing its internal network and the number of hosts on it and submit that to the IP issuing organization. The requesting organization would then receive a block of IP addresses from the issuing organization, based to its needs. The challenge with this was that, if every host on every network in the world was required to have a unique IP address, we would have by now ran out of IP addresses a long time ago, knowing an IP address is a 32bit number, we have just a little over 4 billion ipv4 addresses with over 22 billion devices connecting to the internet as at 2018 and would be 38.6 billion by 2025 and 50 billion by 2050 according to statistical reports.
The concept of private IP addressing was then developed to address the IP address exhaustion problem. The private IP addresses can be used on the private network of any organization in the world and these addresses are not globally unique. In fact, ten organizations can use the same exact ip networks and Ip numbers within their organization and there would be no issues. In fact, most ISP routers in homes use the 192.168.1.0/24 IP range.
These private IP addresses are usually handed to individual computers as they connect to the network through a DHCP server configured by the administrator of the organization with pre-defined private Ip addresses and all this is done through a process called DORA (Discover, Offer, Request, Acknowledge). Internet routers are configured to discard any packets coming from private IP address ranges, so these addresses are not routable on the Internet. But, when these organizations decide to communicate with one another, then a public ip address is used; which will then be routable on the internet.
In this picture, you see two organizations use the same private IP network (10.0.0.0/24) inside their respective internal networks. Because these private IP addresses are not routable on the internet, both organizations can use same private IP addresses from the same range without any issues.
To access the Internet, the organizations will then use a technology called Network Address Translation (NAT), which translates the IP addresses of computers in a local network of each organization to a single public IP address the organizations can use on the internet.
What is Subnetting?
As networks become larger and more complex, speed, efficiency of the network becomes a major concern as traffic traveling through them needs more efficient routes. If all network traffic was traveling across the system at the same time using the same route, bottlenecks and congestion would occur resulting in sluggish and inefficient backlogs.
Creating a subnet allows you to limit the number of routers that network traffic has to pass through. An engineer will effectively create smaller mini-routes within a larger network to allow traffic to travel the shortest distance possible.
- Subnetting divides broadcast domains, meaning that traffic is routed efficiently, improving speed and network performance.
- A subnet mask ensures that traffic remains within its designated subnet. This reduces major congestion and reduces the load imparted on the network. With sub-networks, less distance needs to be traveled by data packets, enhancing network performance.
- With different subnets within your larger network, you can be more aware of route maps. These will help identify potential threats. With subnets in view of security of data, devices will not be able to access the whole network, meaning that companies can dictate which hardware and users have access to more sensitive data thereby boosting Network Security.
- Organization is crucial within large businesses and this also extends to the network and routers. With subnetting, companies have full control over their traffic and data packets.
What Is Subnet Masking?
Each IP address class has a matching “subnet mask,” see ip4 address classification above, it is an easy way of identifying which part of the IP address relates to the network and which part to the host. This is essential to ensure that packets traveling through the network get to the right destination.
The default matching subnet masks for each subnet class are as follows:
- Class A=255.0.0.0
- Class B=255. 255.0.0
- Class C=255.255.255.0
When we look at the subnet masks and convert the decimal numbers back into binary, we can see which bits of the IP address are allocated to the network and which are allocated to the host. In binary, 255 is 11111111, and 0 is 00000000. So a subnet mask of 255.255.255.0 would be converted to 11111111.11111111.11111111.0000000
When you match this with an IP address, such as 192.168.100.120 with a subnet mask of 255.255.255.0, you can determine the network portion and the host portion of the IP address. Example: IP address (192.168.100.120) in binary is 11000000.10101000.01100100.01111000 with subnet mask of 255.255.255.0 (11111111.11111111.11111111.0000000).
Each “1” in the subnet mask exists for the bit portions of the IP address allocated to the network, while each “0” exists for when a bit portion is allocated to the host. This therefore means, the network portion of the subnet is 192.168.100, while the .120 is allocated to the host. When packets arrives on the 192.168.123.0 network, it’ll be processed and then delivered to the 0.0.0.132 host.