Learn Subnetting the Easy Way : A Hands-On Introduction to What is Subnetting, Benefits, and How does it work and More?
What is Subnetting?
The goal of subnetting is to create a fast, efficient, and resilient computer network. As networks become larger and more complex, the 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.
Benefits of Subnetting
- Improve network performance and speed
- Reduce network congestion
- Boost network security
- Control network growth
- Ease administration
1. Improve network performance and speed
Subnetting enables you to ensure that information remains in the subnetted network or broadcast domain, which allows other subnets to maximize their speed and effectiveness. Subnetting also divides your network’s broadcast domains, enabling you to better control traffic flow, thus increasing network performance!
2. Reduce network congestion
Subnetting ensures that traffic destined for a device within a subnet stays in that subnet, which reduces congestion. Through strategic placement of subnets, you can help reduce your network’s load and more efficiently route traffic.
3. Boost network security
You also can split your network using routers to connect subnets though the configuration of ACLs on the routers and switches. As a result, devices in a subnet are unable to access the entire network.
4. Control network growth
When you're planning and designing a network, size is something that needs to be taken into consideration. One of the key benefits of subnetting is that it enables you to control the growth of your network. You can use a popular host formula to determine the size of your network.
5. Ease administration
Subnetting also is an effective way to keep tabs on the machines on your network, which in turn can help you determine which machines need attention should problems arise.
How does it work ?
To understand how subnetting works, we can consider the following example:
In the above image we have one huge network: 10.0.0.0/24. All hosts on the network are in the same subnet, which has the following disadvantages:
- a single broadcast domain – all hosts are in the same broadcast domain. A broadcast sent by any device on the network will be processed by all hosts, creating lots of unnecessary traffic.
network security – each device can reach any other device on the network, which can present security problems. For example, a server containing sensitive information shouldn’t be in the same network as user’s workstations.
organizational problems – in a large networks, different departments are usually grouped into different subnets. For example, you can group all devices from the Accounting department in the same subnet and then give access to sensitive financial data only to hosts from that subnet.
To fix the issue, the network above could be subnetted like this:
Now, two subnets were created for different departments: 10.0.0.0/24 for Accounting and 10.1.0.0/24 for Marketing. Devices in each subnet are now in a different broadcast domain. This will reduce the amount of traffic flowing on the network and allow us to implement packet filtering on the router.
CIDR (Classless Inter-Domain Routing or supernetting)
CIDR, which stands for Classless Inter-Domain Routing, is an IP addressing scheme that improves the allocation of IP addresses. It replaces the old system based on classes A, B, and C. This scheme also helped greatly extend the life of IPv4 as well as slow the growth of routing tables.
In this article, we'll explore how CIDR actually works, as well as provide examples to better demonstrate the concepts explained.
Problems with class-based IP addressing# The old method of IP addressing came with inefficiencies that exhausted the availability of IPv4 addresses faster than it needed to. The classful routing system included classes A, B, and C:
Class A - Over 16 million host identifiers
Class B - 65,535 host identifiers
Class C - 254 host identifiers
The problem would commonly occur when an organization required more than 254 host machines and therefore would no longer fall into class C but rather class B. This means that the organization would use a class B license even though they had far less than 65,535 hosts. Therefore if an organization only required 2,500 hosts, they would be wasting about 63,000 hosts by holding a class B license which would greatly decrease the availability of IPv4 addresses unnecessarily.